Android应用程序键盘（Keyboard）消息处理机制分析
2011-11-16 23:19
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在Android系统中，键盘按键事件是由WindowManagerService服务来管理的，然后再以消息的形式来分发给应用程序处理，不过和普通消息不一样，它是由硬件中断触发的；在上一篇文章《Android应用程序消息处理机制（Looper、Handler）分析》中，我们分析了Android应用程序的消息处理机制，本文将结合这种消息处理机制来详细分析Android应用程序是如何获得键盘按键消息的。
在系统启动的时候，SystemServer会启动窗口管理服务WindowManagerService，WindowManagerService在启动的时候就会通过系统输入管理器InputManager来总负责监控键盘消息。这些键盘消息一般都是分发给当前激活的Activity窗口来处理的，因此，当前激活的Activity窗口在创建的时候，会到WindowManagerService中去注册一个接收键盘消息的通道，表明它要处理键盘消息，而当InputManager监控到有键盘消息时，就会分给给它处理。当当前激活的Activity窗口不再处于激活状态时，它也会到WindowManagerService中去反注册之前的键盘消息接收通道，这样，InputManager就不会再把键盘消息分发给它来处理。由于本文的内容比较多，在接下面的章节中，我们将分为五个部分来详细描述Android应用程序获得键盘按键消息的过程，每一个部分都是具体描述键盘消息处理过程中的一个过程。结合上面的键盘消息处理框架，这四个过程分别是InputManager的启动过程、应用程序注册键盘消息接收通道的过程、InputManager分发键盘消息给应用程序的过程以及应用程序注销键盘消息接收通道的过程。为了更好地理解Android应用程序获得键盘按键消息的整个过程，建议读者首先阅读Android应用程序消息处理机制（Looper、Handler）分析一文，理解了Android应用程序的消息处理机制后，就能很好的把握本文的内容。
1. InputManager的启动过程分析
前面说过，Android系统的键盘事件是由InputManager来监控的，而InputManager是由窗口管理服务WindowManagerService来启动的。
从前面一篇文章Android系统进程Zygote启动过程的源代码分析中，我们知道在Android系统中，Zygote进程负责启动系统服务进程SystemServer，而系统服务进程SystemServer负责启动系统中的各种关键服务，例如我们在前面两篇文章Android应用程序安装过程源代码分析和Android系统默认Home应用程序（Launcher）的启动过程源代码分析中提到的Package管理服务PackageManagerService和Activity管理服务ActivityManagerService。这里我们所讨论的窗口管理服务WindowManagerService也是由SystemServer来启动的，具体的启动过程这里就不再详述了，具体可以参考PackageManagerService和ActivityManagerService的启动过程。
了解了WindowManagerService的启动过程之后，我们就可以继续分析InputManager的启动过程了。我们先来看一下InputManager启动过程的序列图，然后根据这个序列图来一步步分析它的启动过程：
点击查看大图
Step 1. WindowManagerService.main
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
public static WindowManagerService main(Context context,
PowerManagerService pm, boolean haveInputMethods) {
WMThread thr = new WMThread(context, pm, haveInputMethods);
thr.start();
synchronized (thr) {
while (thr.mService == null) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
return thr.mService;
}
}
......
}
view plaincopy to clipboardprint? public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... static class WMThread extends Thread { ...... public void run() { ...... WindowManagerService s = new WindowManagerService(mContext, mPM, mHaveInputMethods); ...... } } ...... } public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... static class WMThread extends Thread { ...... public void run() { ...... WindowManagerService s = new WindowManagerService(mContext, mPM, mHaveInputMethods); ...... } } ...... }这里执行的主要操作就是创建一个WindowManagerService实例，这样会调用到WindowManagerService构造函数中去。
Step 3. WindowManagerService<init>
WindowManagerService类的构造函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
final InputManager mInputManager;
......
private WindowManagerService(Context context, PowerManagerService pm,
boolean haveInputMethods) {
......
mInputManager = new InputManager(context, this);
......
mInputManager.start();
......
}
......
}
view plaincopy to clipboardprint? public class InputManager { ...... public InputManager(Context context, WindowManagerService windowManagerService) { this.mContext = context; this.mWindowManagerService = windowManagerService; this.mCallbacks = new Callbacks(); init(); } ...... } public class InputManager { ...... public InputManager(Context context, WindowManagerService windowManagerService) { this.mContext = context; this.mWindowManagerService = windowManagerService; this.mCallbacks = new Callbacks(); init(); } ...... }这里只是简单地初始化InputManager类的一些成员变量，然后调用init函数进一步执行初始化操作。
Step 5. InputManager.init
这个函数定义在frameworks/base/services/java/com/android/server/InputManager.java文件中：
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public class InputManager {
......
private void init() {
Slog.i(TAG, "Initializing input manager");
nativeInit(mCallbacks);
}
......
}
view plaincopy to clipboardprint? static void android_server_InputManager_nativeInit(JNIEnv* env, jclass clazz, jobject callbacks) { if (gNativeInputManager == NULL) { gNativeInputManager = new NativeInputManager(callbacks); } else { LOGE("Input manager already initialized."); jniThrowRuntimeException(env, "Input manager already initialized."); } } static void android_server_InputManager_nativeInit(JNIEnv* env, jclass clazz, jobject callbacks) { if (gNativeInputManager == NULL) { gNativeInputManager = new NativeInputManager(callbacks); } else { LOGE("Input manager already initialized."); jniThrowRuntimeException(env, "Input manager already initialized."); } }这个函数的作用是创建一个NativeInputManager实例，并保存在gNativeInputManager变量中。由于是第一次调用到这里，因此，gNativeInputManager为NULL，于是就会new一个NativeInputManager对象出来，这样就会执行NativeInputManager类的构造函数来执其它的初始化操作。
Step 7. NativeInputManager<init>
NativeInputManager类的构造函数定义在frameworks/base/services/jni$ vi com_android_server_InputManager.cpp文件中：
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NativeInputManager::NativeInputManager(jobject callbacksObj) :
mFilterTouchEvents(-1), mFilterJumpyTouchEvents(-1), mVirtualKeyQuietTime(-1),
mMaxEventsPerSecond(-1),
mDisplayWidth(-1), mDisplayHeight(-1), mDisplayOrientation(ROTATION_0) {
JNIEnv* env = jniEnv();
mCallbacksObj = env->NewGlobalRef(callbacksObj);
sp<EventHub> eventHub = new EventHub();
mInputManager = new InputManager(eventHub, this, this);
}
view plaincopy to clipboardprint? InputManager::InputManager( const sp<EventHubInterface>& eventHub, const sp<InputReaderPolicyInterface>& readerPolicy, const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) { mDispatcher = new InputDispatcher(dispatcherPolicy); mReader = new InputReader(eventHub, readerPolicy, mDispatcher); initialize(); } InputManager::InputManager( const sp<EventHubInterface>& eventHub, const sp<InputReaderPolicyInterface>& readerPolicy, const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) { mDispatcher = new InputDispatcher(dispatcherPolicy); mReader = new InputReader(eventHub, readerPolicy, mDispatcher); initialize(); }这里主要是创建了一个InputDispatcher对象和一个InputReader对象，并且分别保存在成员变量mDispatcher和mReader中。InputDispatcher类是负责把键盘消息分发给当前激活的Activity窗口的，而InputReader类则是通过EventHub类来实现读取键盘事件的，后面我们会进一步分析。创建了这两个对象后，还要调用initialize函数来执行其它的初始化操作。
Step 9. InputManager.initialize
这个函数定义在frameworks/base/libs/ui/InputManager.cpp 文件中：
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void InputManager::initialize() {
mReaderThread = new InputReaderThread(mReader);
mDispatcherThread = new InputDispatcherThread(mDispatcher);
}
view plaincopy to clipboardprint? public class InputManager { ...... public void start() { Slog.i(TAG, "Starting input manager"); nativeStart(); } ...... } public class InputManager { ...... public void start() { Slog.i(TAG, "Starting input manager"); nativeStart(); } ...... }这个函数通过调用本地方法nativeStart来执行进一步的启动操作。
Step 11. InputManager.nativeStart
这个函数定义在frameworks/base/services/jni$ vi com_android_server_InputManager.cpp文件中：
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static void android_server_InputManager_nativeStart(JNIEnv* env, jclass clazz) {
if (checkInputManagerUnitialized(env)) {
return;
}
status_t result = gNativeInputManager->getInputManager()->start();
if (result) {
jniThrowRuntimeException(env, "Input manager could not be started.");
}
}
view plaincopy to clipboardprint? status_t InputManager::start() { status_t result = mDispatcherThread->run("InputDispatcher", PRIORITY_URGENT_DISPLAY); if (result) { LOGE("Could not start InputDispatcher thread due to error %d.", result); return result; } result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY); if (result) { LOGE("Could not start InputReader thread due to error %d.", result); mDispatcherThread->requestExit(); return result; } return OK; } status_t InputManager::start() { status_t result = mDispatcherThread->run("InputDispatcher", PRIORITY_URGENT_DISPLAY); if (result) { LOGE("Could not start InputDispatcher thread due to error %d.", result); return result; } result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY); if (result) { LOGE("Could not start InputReader thread due to error %d.", result); mDispatcherThread->requestExit(); return result; } return OK; }这个函数主要就是分别启动一个InputDispatcherThread线程和一个InputReaderThread线程来读取和分发键盘消息的了。这里的InputDispatcherThread线程对象mDispatcherThread和InputReaderThread线程对象是在前面的Step 9中创建的，调用了它们的run函数后，就会进入到它们的threadLoop函数中去，只要threadLoop函数返回true，函数threadLoop就会一直被循环调用，于是这两个线程就起到了不断地读取和分发键盘消息的作用。
我们先来分析InputDispatcherThread线程分发消息的过程，然后再回过头来分析InputReaderThread线程读取消息的过程。
Step 13. InputDispatcherThread.threadLoop
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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bool InputDispatcherThread::threadLoop() {
mDispatcher->dispatchOnce();
return true;
}
view plaincopy to clipboardprint? void InputDispatcher::dispatchOnce() { nsecs_t keyRepeatTimeout = mPolicy->getKeyRepeatTimeout(); nsecs_t keyRepeatDelay = mPolicy->getKeyRepeatDelay(); nsecs_t nextWakeupTime = LONG_LONG_MAX; { // acquire lock AutoMutex _l(mLock); dispatchOnceInnerLocked(keyRepeatTimeout, keyRepeatDelay, & nextWakeupTime); if (runCommandsLockedInterruptible()) { nextWakeupTime = LONG_LONG_MIN; // force next poll to wake up immediately } } // release lock // Wait for callback or timeout or wake. (make sure we round up, not down) nsecs_t currentTime = now(); int32_t timeoutMillis; if (nextWakeupTime > currentTime) { uint64_t timeout = uint64_t(nextWakeupTime - currentTime); timeout = (timeout + 999999LL) / 1000000LL; timeoutMillis = timeout > INT_MAX ? -1 : int32_t(timeout); } else { timeoutMillis = 0; } mLooper->pollOnce(timeoutMillis); } void InputDispatcher::dispatchOnce() { nsecs_t keyRepeatTimeout = mPolicy->getKeyRepeatTimeout(); nsecs_t keyRepeatDelay = mPolicy->getKeyRepeatDelay(); nsecs_t nextWakeupTime = LONG_LONG_MAX; { // acquire lock AutoMutex _l(mLock); dispatchOnceInnerLocked(keyRepeatTimeout, keyRepeatDelay, & nextWakeupTime); if (runCommandsLockedInterruptible()) { nextWakeupTime = LONG_LONG_MIN; // force next poll to wake up immediately } } // release lock // Wait for callback or timeout or wake. (make sure we round up, not down) nsecs_t currentTime = now(); int32_t timeoutMillis; if (nextWakeupTime > currentTime) { uint64_t timeout = uint64_t(nextWakeupTime - currentTime); timeout = (timeout + 999999LL) / 1000000LL; timeoutMillis = timeout > INT_MAX ? -1 : int32_t(timeout); } else { timeoutMillis = 0; } mLooper->pollOnce(timeoutMillis); }这个函数很简单，把键盘消息交给dispatchOnceInnerLocked函数来处理，这个过程我们在后面再详细分析，然后调用mLooper->pollOnce函数等待下一次键盘事件的发生。这里的成员变量mLooper的类型为Looper，它定义在C++层中，具体可以参考前面Android应用程序消息处理机制（Looper、Handler）分析一文。
Step 15. Looper.pollOnce
这个函数定义在frameworks/base/libs/utils/Looper.cpp文件中，具体可以参考前面Android应用程序消息处理机制（Looper、Handler）分析一文，这里就不再详述了。总的来说，就是在Looper类中，会创建一个管道，当调用Looper类的pollOnce函数时，如果管道中没有内容可读，那么当前线程就会进入到空闲等待状态；当有键盘事件发生时，InputReader就会往这个管道中写入新的内容，这样就会唤醒前面正在等待键盘事件发生的线程。
InputDispatcher类分发消息的过程就暂时分析到这里，后面会有更进一步的分析，现在，我们回到Step 12中，接着分析InputReader类读取键盘事件的过程。在调用了InputReaderThread线程类的run就函数后，同样会进入到InputReaderThread线程类的threadLoop函数中去。
Step 16. InputReaderThread.threadLoop
这个函数定义在frameworks/base/libs/ui/InputReader.cpp文件中：
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bool InputReaderThread::threadLoop() {
mReader->loopOnce();
return true;
}
view plaincopy to clipboardprint? void InputReader::loopOnce() { RawEvent rawEvent; mEventHub->getEvent(& rawEvent); #if DEBUG_RAW_EVENTS LOGD("Input event: device=0x%x type=0x%x scancode=%d keycode=%d value=%d", rawEvent.deviceId, rawEvent.type, rawEvent.scanCode, rawEvent.keyCode, rawEvent.value); #endif process(& rawEvent); } void InputReader::loopOnce() { RawEvent rawEvent; mEventHub->getEvent(& rawEvent); #if DEBUG_RAW_EVENTS LOGD("Input event: device=0x%x type=0x%x scancode=%d keycode=%d value=%d", rawEvent.deviceId, rawEvent.type, rawEvent.scanCode, rawEvent.keyCode, rawEvent.value); #endif process(& rawEvent); }这里通过成员函数mEventHub来负责键盘消息的读取工作，如果当前有键盘事件发生或者有键盘事件等待处理，通过mEventHub的getEvent函数就可以得到这个事件，然后交给process函数进行处理，这个函数主要就是唤醒前面的InputDispatcherThread线程，通知它有新的键盘事件发生了，它需要进行一次键盘消息的分发操作了，这个函数我们后面再进一步详细分析；如果没有键盘事件发生或者没有键盘事件等待处理，那么调用mEventHub的getEvent函数时就会进入等待状态。
Step 18. EventHub.getEvent
这个函数定义在frameworks/base/libs/ui/EventHub.cpp文件中：
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bool EventHub::getEvent(RawEvent* outEvent)
{
outEvent->deviceId = 0;
outEvent->type = 0;
outEvent->scanCode = 0;
outEvent->keyCode = 0;
outEvent->flags = 0;
outEvent->value = 0;
outEvent->when = 0;
// Note that we only allow one caller to getEvent(), so don't need
// to do locking here... only when adding/removing devices.
if (!mOpened) {
mError = openPlatformInput() ? NO_ERROR : UNKNOWN_ERROR;
mOpened = true;
mNeedToSendFinishedDeviceScan = true;
}
for (;;) {
// Report any devices that had last been added/removed.
if (mClosingDevices != NULL) {
device_t* device = mClosingDevices;
LOGV("Reporting device closed: id=0x%x, name=%s\n",
device->id, device->path.string());
mClosingDevices = device->next;
if (device->id == mFirstKeyboardId) {
outEvent->deviceId = 0;
} else {
outEvent->deviceId = device->id;
}
outEvent->type = DEVICE_REMOVED;
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
delete device;
mNeedToSendFinishedDeviceScan = true;
return true;
}
if (mOpeningDevices != NULL) {
device_t* device = mOpeningDevices;
LOGV("Reporting device opened: id=0x%x, name=%s\n",
device->id, device->path.string());
mOpeningDevices = device->next;
if (device->id == mFirstKeyboardId) {
outEvent->deviceId = 0;
} else {
outEvent->deviceId = device->id;
}
outEvent->type = DEVICE_ADDED;
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
mNeedToSendFinishedDeviceScan = true;
return true;
}
if (mNeedToSendFinishedDeviceScan) {
mNeedToSendFinishedDeviceScan = false;
outEvent->type = FINISHED_DEVICE_SCAN;
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
return true;
}
// Grab the next input event.
for (;;) {
// Consume buffered input events, if any.
if (mInputBufferIndex < mInputBufferCount) {
const struct input_event& iev = mInputBufferData[mInputBufferIndex++];
const device_t* device = mDevices[mInputDeviceIndex];
LOGV("%s got: t0=%d, t1=%d, type=%d, code=%d, v=%d", device->path.string(),
(int) iev.time.tv_sec, (int) iev.time.tv_usec, iev.type, iev.code, iev.value);
if (device->id == mFirstKeyboardId) {
outEvent->deviceId = 0;
} else {
outEvent->deviceId = device->id;
}
outEvent->type = iev.type;
outEvent->scanCode = iev.code;
if (iev.type == EV_KEY) {
status_t err = device->layoutMap->map(iev.code,
& outEvent->keyCode, & outEvent->flags);
LOGV("iev.code=%d keyCode=%d flags=0x%08x err=%d\n",
iev.code, outEvent->keyCode, outEvent->flags, err);
if (err != 0) {
outEvent->keyCode = AKEYCODE_UNKNOWN;
outEvent->flags = 0;
}
} else {
outEvent->keyCode = iev.code;
}
outEvent->value = iev.value;
// Use an event timestamp in the same timebase as
// java.lang.System.nanoTime() and android.os.SystemClock.uptimeMillis()
// as expected by the rest of the system.
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
return true;
}
// Finish reading all events from devices identified in previous poll().
// This code assumes that mInputDeviceIndex is initially 0 and that the
// revents member of pollfd is initialized to 0 when the device is first added.
// Since mFDs[0] is used for inotify, we process regular events starting at index 1.
mInputDeviceIndex += 1;
if (mInputDeviceIndex >= mFDCount) {
break;
}
const struct pollfd& pfd = mFDs[mInputDeviceIndex];
if (pfd.revents & POLLIN) {
int32_t readSize = read(pfd.fd, mInputBufferData,
sizeof(struct input_event) * INPUT_BUFFER_SIZE);
if (readSize < 0) {
if (errno != EAGAIN && errno != EINTR) {
LOGW("could not get event (errno=%d)", errno);
}
} else if ((readSize % sizeof(struct input_event)) != 0) {
LOGE("could not get event (wrong size: %d)", readSize);
} else {
mInputBufferCount = readSize / sizeof(struct input_event);
mInputBufferIndex = 0;
}
}
}
......
mInputDeviceIndex = 0;
// Poll for events. Mind the wake lock dance!
// We hold a wake lock at all times except during poll(). This works due to some
// subtle choreography. When a device driver has pending (unread) events, it acquires
// a kernel wake lock. However, once the last pending event has been read, the device
// driver will release the kernel wake lock. To prevent the system from going to sleep
// when this happens, the EventHub holds onto its own user wake lock while the client
// is processing events. Thus the system can only sleep if there are no events
// pending or currently being processed.
release_wake_lock(WAKE_LOCK_ID);
int pollResult = poll(mFDs, mFDCount, -1);
acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);
if (pollResult <= 0) {
if (errno != EINTR) {
LOGW("poll failed (errno=%d)\n", errno);
usleep(100000);
}
}
}
}
view plaincopy to clipboardprint? bool EventHub::openPlatformInput(void) { ...... res = scanDir(device_path); if(res < 0) { LOGE("scan dir failed for %s\n", device_path); } return true; } bool EventHub::openPlatformInput(void) { ...... res = scanDir(device_path); if(res < 0) { LOGE("scan dir failed for %s\n", device_path); } return true; }这个函数主要是扫描device_path目录下的设备文件，然后打开它们，这里的变量device_path定义在frameworks/base/libs/ui/EventHub.cpp文件开始的地方：
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static const char *device_path = "/dev/input";
view plaincopy to clipboardprint? int EventHub::scanDir(const char *dirname) { char devname[PATH_MAX]; char *filename; DIR *dir; struct dirent *de; dir = opendir(dirname); if(dir == NULL) return -1; strcpy(devname, dirname); filename = devname + strlen(devname); *filename++ = '/'; while((de = readdir(dir))) { if(de->d_name[0] == '.' && (de->d_name[1] == '\0' || (de->d_name[1] == '.' && de->d_name[2] == '\0'))) continue; strcpy(filename, de->d_name); openDevice(devname); } closedir(dir); return 0; } int EventHub::scanDir(const char *dirname) { char devname[PATH_MAX]; char *filename; DIR *dir; struct dirent *de; dir = opendir(dirname); if(dir == NULL) return -1; strcpy(devname, dirname); filename = devname + strlen(devname); *filename++ = '/'; while((de = readdir(dir))) { if(de->d_name[0] == '.' && (de->d_name[1] == '\0' || (de->d_name[1] == '.' && de->d_name[2] == '\0'))) continue; strcpy(filename, de->d_name); openDevice(devname); } closedir(dir); return 0; }根据上面一步的分析，这个函数主要就是调用openDevice函数来分别打开/dev/input/event0、/dev/input/mice和/dev/input/mouse0三个设备文件了。
Step 21. EventHub.openDevice
这个函数定义在frameworks/base/libs/ui/EventHub.cpp文件中：
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int EventHub::openDevice(const char *deviceName) {
int version;
int fd;
struct pollfd *new_mFDs;
device_t **new_devices;
char **new_device_names;
char name[80];
char location[80];
char idstr[80];
struct input_id id;
LOGV("Opening device: %s", deviceName);
AutoMutex _l(mLock);
fd = open(deviceName, O_RDWR);
if(fd < 0) {
LOGE("could not open %s, %s\n", deviceName, strerror(errno));
return -1;
}
......
int devid = 0;
while (devid < mNumDevicesById) {
if (mDevicesById[devid].device == NULL) {
break;
}
devid++;
}
......
mDevicesById[devid].seq = (mDevicesById[devid].seq+(1<<SEQ_SHIFT))&SEQ_MASK;
if (mDevicesById[devid].seq == 0) {
mDevicesById[devid].seq = 1<<SEQ_SHIFT;
}
new_mFDs = (pollfd*)realloc(mFDs, sizeof(mFDs[0]) * (mFDCount + 1));
new_devices = (device_t**)realloc(mDevices, sizeof(mDevices[0]) * (mFDCount + 1));
if (new_mFDs == NULL || new_devices == NULL) {
LOGE("out of memory");
return -1;
}
mFDs = new_mFDs;
mDevices = new_devices;
......
device_t* device = new device_t(devid|mDevicesById[devid].seq, deviceName, name);
if (device == NULL) {
LOGE("out of memory");
return -1;
}
device->fd = fd;
mFDs[mFDCount].fd = fd;
mFDs[mFDCount].events = POLLIN;
mFDs[mFDCount].revents = 0;
// Figure out the kinds of events the device reports.
uint8_t key_bitmask[sizeof_bit_array(KEY_MAX + 1)];
memset(key_bitmask, 0, sizeof(key_bitmask));
LOGV("Getting keys...");
if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) {
// See if this is a keyboard. Ignore everything in the button range except for
// gamepads which are also considered keyboards.
if (containsNonZeroByte(key_bitmask, 0, sizeof_bit_array(BTN_MISC))
|| containsNonZeroByte(key_bitmask, sizeof_bit_array(BTN_GAMEPAD),
sizeof_bit_array(BTN_DIGI))
|| containsNonZeroByte(key_bitmask, sizeof_bit_array(KEY_OK),
sizeof_bit_array(KEY_MAX + 1))) {
device->classes |= INPUT_DEVICE_CLASS_KEYBOARD;
device->keyBitmask = new uint8_t[sizeof(key_bitmask)];
if (device->keyBitmask != NULL) {
memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask));
} else {
delete device;
LOGE("out of memory allocating key bitmask");
return -1;
}
}
}
......
if ((device->classes & INPUT_DEVICE_CLASS_KEYBOARD) != 0) {
char tmpfn[sizeof(name)];
char keylayoutFilename[300];
// a more descriptive name
device->name = name;
// replace all the spaces with underscores
strcpy(tmpfn, name);
for (char *p = strchr(tmpfn, ' '); p && *p; p = strchr(tmpfn, ' '))
*p = '_';
// find the .kl file we need for this device
const char* root = getenv("ANDROID_ROOT");
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s.kl", root, tmpfn);
bool defaultKeymap = false;
if (access(keylayoutFilename, R_OK)) {
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s", root, "qwerty.kl");
defaultKeymap = true;
}
status_t status = device->layoutMap->load(keylayoutFilename);
if (status) {
LOGE("Error %d loading key layout.", status);
}
// tell the world about the devname (the descriptive name)
if (!mHaveFirstKeyboard && !defaultKeymap && strstr(name, "-keypad")) {
// the built-in keyboard has a well-known device ID of 0,
// this device better not go away.
mHaveFirstKeyboard = true;
mFirstKeyboardId = device->id;
property_set("hw.keyboards.0.devname", name);
} else {
// ensure mFirstKeyboardId is set to -something-.
if (mFirstKeyboardId == 0) {
mFirstKeyboardId = device->id;
}
}
char propName[100];
sprintf(propName, "hw.keyboards.%u.devname", device->id);
property_set(propName, name);
// 'Q' key support = cheap test of whether this is an alpha-capable kbd
if (hasKeycodeLocked(device, AKEYCODE_Q)) {
device->classes |= INPUT_DEVICE_CLASS_ALPHAKEY;
}
// See if this device has a DPAD.
if (hasKeycodeLocked(device, AKEYCODE_DPAD_UP) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_DOWN) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_LEFT) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_RIGHT) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_CENTER)) {
device->classes |= INPUT_DEVICE_CLASS_DPAD;
}
// See if this device has a gamepad.
for (size_t i = 0; i < sizeof(GAMEPAD_KEYCODES)/sizeof(GAMEPAD_KEYCODES[0]); i++) {
if (hasKeycodeLocked(device, GAMEPAD_KEYCODES[i])) {
device->classes |= INPUT_DEVICE_CLASS_GAMEPAD;
break;
}
}
LOGI("New keyboard: device->id=0x%x devname='%s' propName='%s' keylayout='%s'\n",
device->id, name, propName, keylayoutFilename);
}
......
mDevicesById[devid].device = device;
device->next = mOpeningDevices;
mOpeningDevices = device;
mDevices[mFDCount] = device;
mFDCount++;
return 0;
}
view plaincopy to clipboardprint? fd = open(deviceName, O_RDWR); fd = open(deviceName, O_RDWR);系统中所有输入设备文件信息都保存在成员变量mDevicesById中，因此，先在mDevicesById找到一个空位置来保存当前打开的设备文件信息：
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mDevicesById[devid].seq = (mDevicesById[devid].seq+(1<<SEQ_SHIFT))&SEQ_MASK;
if (mDevicesById[devid].seq == 0) {
mDevicesById[devid].seq = 1<<SEQ_SHIFT;
}
view plaincopy to clipboardprint? mDevicesById[devid].seq = (mDevicesById[devid].seq+(1<<SEQ_SHIFT))&SEQ_MASK; if (mDevicesById[devid].seq == 0) { mDevicesById[devid].seq = 1<<SEQ_SHIFT; } new_mFDs = (pollfd*)realloc(mFDs, sizeof(mFDs[0]) * (mFDCount + 1)); new_devices = (device_t**)realloc(mDevices, sizeof(mDevices[0]) * (mFDCount + 1)); if (new_mFDs == NULL || new_devices == NULL) { LOGE("out of memory"); return -1; } mFDs = new_mFDs; mDevices = new_devices; ...... device_t* device = new device_t(devid|mDevicesById[devid].seq, deviceName, name); if (device == NULL) { LOGE("out of memory"); return -1; } device->fd = fd; mDevicesById[devid].seq = (mDevicesById[devid].seq+(1<<SEQ_SHIFT))&SEQ_MASK; if (mDevicesById[devid].seq == 0) { mDevicesById[devid].seq = 1<<SEQ_SHIFT; } new_mFDs = (pollfd*)realloc(mFDs, sizeof(mFDs[0]) * (mFDCount + 1)); new_devices = (device_t**)realloc(mDevices, sizeof(mDevices[0]) * (mFDCount + 1)); if (new_mFDs == NULL || new_devices == NULL) { LOGE("out of memory"); return -1; } mFDs = new_mFDs; mDevices = new_devices; ...... device_t* device = new device_t(devid|mDevicesById[devid].seq, deviceName, name); if (device == NULL) { LOGE("out of memory"); return -1; } device->fd = fd;
同时，这个设备文件还会保存在数组mFDs中：
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mFDs[mFDCount].fd = fd;
mFDs[mFDCount].events = POLLIN;
mFDs[mFDCount].revents = 0;
view plaincopy to clipboardprint? // Figure out the kinds of events the device reports. uint8_t key_bitmask[sizeof_bit_array(KEY_MAX + 1)]; memset(key_bitmask, 0, sizeof(key_bitmask)); LOGV("Getting keys..."); if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) { // See if this is a keyboard. Ignore everything in the button range except for // gamepads which are also considered keyboards. if (containsNonZeroByte(key_bitmask, 0, sizeof_bit_array(BTN_MISC)) || containsNonZeroByte(key_bitmask, sizeof_bit_array(BTN_GAMEPAD), sizeof_bit_array(BTN_DIGI)) || containsNonZeroByte(key_bitmask, sizeof_bit_array(KEY_OK), sizeof_bit_array(KEY_MAX + 1))) { device->classes |= INPUT_DEVICE_CLASS_KEYBOARD; device->keyBitmask = new uint8_t[sizeof(key_bitmask)]; if (device->keyBitmask != NULL) { memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask)); } else { delete device; LOGE("out of memory allocating key bitmask"); return -1; } } } // Figure out the kinds of events the device reports. uint8_t key_bitmask[sizeof_bit_array(KEY_MAX + 1)]; memset(key_bitmask, 0, sizeof(key_bitmask)); LOGV("Getting keys..."); if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) { // See if this is a keyboard. Ignore everything in the button range except for // gamepads which are also considered keyboards. if (containsNonZeroByte(key_bitmask, 0, sizeof_bit_array(BTN_MISC)) || containsNonZeroByte(key_bitmask, sizeof_bit_array(BTN_GAMEPAD), sizeof_bit_array(BTN_DIGI)) || containsNonZeroByte(key_bitmask, sizeof_bit_array(KEY_OK), sizeof_bit_array(KEY_MAX + 1))) { device->classes |= INPUT_DEVICE_CLASS_KEYBOARD; device->keyBitmask = new uint8_t[sizeof(key_bitmask)]; if (device->keyBitmask != NULL) { memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask)); } else { delete device; LOGE("out of memory allocating key bitmask"); return -1; } } }如果是的话，还要继续进一步初始化前面为这个设备文件所创建的device_t结构体，主要就是把结构体device的classes成员变量的INPUT_DEVICE_CLASS_KEYBOARD位置为1了，以表明这是一个键盘。
如果是键盘设备，初始化工作还未完成，还要继续设置键盘的布局等信息：
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if ((device->classes & INPUT_DEVICE_CLASS_KEYBOARD) != 0) {
char tmpfn[sizeof(name)];
char keylayoutFilename[300];
// a more descriptive name
device->name = name;
// replace all the spaces with underscores
strcpy(tmpfn, name);
for (char *p = strchr(tmpfn, ' '); p && *p; p = strchr(tmpfn, ' '))
*p = '_';
// find the .kl file we need for this device
const char* root = getenv("ANDROID_ROOT");
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s.kl", root, tmpfn);
bool defaultKeymap = false;
if (access(keylayoutFilename, R_OK)) {
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s", root, "qwerty.kl");
defaultKeymap = true;
}
status_t status = device->layoutMap->load(keylayoutFilename);
if (status) {
LOGE("Error %d loading key layout.", status);
}
// tell the world about the devname (the descriptive name)
if (!mHaveFirstKeyboard && !defaultKeymap && strstr(name, "-keypad")) {
// the built-in keyboard has a well-known device ID of 0,
// this device better not go away.
mHaveFirstKeyboard = true;
mFirstKeyboardId = device->id;
property_set("hw.keyboards.0.devname", name);
} else {
// ensure mFirstKeyboardId is set to -something-.
if (mFirstKeyboardId == 0) {
mFirstKeyboardId = device->id;
}
}
char propName[100];
sprintf(propName, "hw.keyboards.%u.devname", device->id);
property_set(propName, name);
// 'Q' key support = cheap test of whether this is an alpha-capable kbd
if (hasKeycodeLocked(device, AKEYCODE_Q)) {
device->classes |= INPUT_DEVICE_CLASS_ALPHAKEY;
}
// See if this device has a DPAD.
if (hasKeycodeLocked(device, AKEYCODE_DPAD_UP) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_DOWN) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_LEFT) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_RIGHT) &&
hasKeycodeLocked(device, AKEYCODE_DPAD_CENTER)) {
device->classes |= INPUT_DEVICE_CLASS_DPAD;
}
// See if this device has a gamepad.
for (size_t i = 0; i < sizeof(GAMEPAD_KEYCODES)/sizeof(GAMEPAD_KEYCODES[0]); i++) {
if (hasKeycodeLocked(device, GAMEPAD_KEYCODES[i])) {
device->classes |= INPUT_DEVICE_CLASS_GAMEPAD;
break;
}
}
LOGI("New keyboard: device->id=0x%x devname='%s' propName='%s' keylayout='%s'\n",
device->id, name, propName, keylayoutFilename);
}
view plaincopy to clipboardprint? // Report any devices that had last been added/removed. if (mClosingDevices != NULL) { device_t* device = mClosingDevices; LOGV("Reporting device closed: id=0x%x, name=%s\n", device->id, device->path.string()); mClosingDevices = device->next; if (device->id == mFirstKeyboardId) { outEvent->deviceId = 0; } else { outEvent->deviceId = device->id; } outEvent->type = DEVICE_REMOVED; outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC); delete device; mNeedToSendFinishedDeviceScan = true; return true; } // Report any devices that had last been added/removed. if (mClosingDevices != NULL) { device_t* device = mClosingDevices; LOGV("Reporting device closed: id=0x%x, name=%s\n", device->id, device->path.string()); mClosingDevices = device->next; if (device->id == mFirstKeyboardId) { outEvent->deviceId = 0; } else { outEvent->deviceId = device->id; } outEvent->type = DEVICE_REMOVED; outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC); delete device; mNeedToSendFinishedDeviceScan = true; return true; }接着，检查当前是否有新的输入设备加入进来：
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if (mOpeningDevices != NULL) {
device_t* device = mOpeningDevices;
LOGV("Reporting device opened: id=0x%x, name=%s\n",
device->id, device->path.string());
mOpeningDevices = device->next;
if (device->id == mFirstKeyboardId) {
outEvent->deviceId = 0;
} else {
outEvent->deviceId = device->id;
}
outEvent->type = DEVICE_ADDED;
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
mNeedToSendFinishedDeviceScan = true;
return true;
}
view plaincopy to clipboardprint? if (mNeedToSendFinishedDeviceScan) { mNeedToSendFinishedDeviceScan = false; outEvent->type = FINISHED_DEVICE_SCAN; outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC); return true; } if (mNeedToSendFinishedDeviceScan) { mNeedToSendFinishedDeviceScan = false; outEvent->type = FINISHED_DEVICE_SCAN; outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC); return true; }最后，就是要检查当前是否有还未处理的输入设备事件发生了：
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// Grab the next input event.
for (;;) {
// Consume buffered input events, if any.
if (mInputBufferIndex < mInputBufferCount) {
const struct input_event& iev = mInputBufferData[mInputBufferIndex++];
const device_t* device = mDevices[mInputDeviceIndex];
LOGV("%s got: t0=%d, t1=%d, type=%d, code=%d, v=%d", device->path.string(),
(int) iev.time.tv_sec, (int) iev.time.tv_usec, iev.type, iev.code, iev.value);
if (device->id == mFirstKeyboardId) {
outEvent->deviceId = 0;
} else {
outEvent->deviceId = device->id;
}
outEvent->type = iev.type;
outEvent->scanCode = iev.code;
if (iev.type == EV_KEY) {
status_t err = device->layoutMap->map(iev.code,
& outEvent->keyCode, & outEvent->flags);
LOGV("iev.code=%d keyCode=%d flags=0x%08x err=%d\n",
iev.code, outEvent->keyCode, outEvent->flags, err);
if (err != 0) {
outEvent->keyCode = AKEYCODE_UNKNOWN;
outEvent->flags = 0;
}
} else {
outEvent->keyCode = iev.code;
}
outEvent->value = iev.value;
// Use an event timestamp in the same timebase as
// java.lang.System.nanoTime() and android.os.SystemClock.uptimeMillis()
// as expected by the rest of the system.
outEvent->when = systemTime(SYSTEM_TIME_MONOTONIC);
return true;
}
// Finish reading all events from devices identified in previous poll().
// This code assumes that mInputDeviceIndex is initially 0 and that the
// revents member of pollfd is initialized to 0 when the device is first added.
// Since mFDs[0] is used for inotify, we process regular events starting at index 1.
mInputDeviceIndex += 1;
if (mInputDeviceIndex >= mFDCount) {
break;
}
const struct pollfd& pfd = mFDs[mInputDeviceIndex];
if (pfd.revents & POLLIN) {
int32_t readSize = read(pfd.fd, mInputBufferData,
sizeof(struct input_event) * INPUT_BUFFER_SIZE);
if (readSize < 0) {
if (errno != EAGAIN && errno != EINTR) {
LOGW("could not get event (errno=%d)", errno);
}
} else if ((readSize % sizeof(struct input_event)) != 0) {
LOGE("could not get event (wrong size: %d)", readSize);
} else {
mInputBufferCount = readSize / sizeof(struct input_event);
mInputBufferIndex = 0;
}
}
}
view plaincopy to clipboardprint? int pollResult = poll(mFDs, mFDCount, -1); int pollResult = poll(mFDs, mFDCount, -1);
这里的mFDs包含了我们所要监控的输入设备的打开文件描述符，这是在前面的openPlatformInput函数中初始化的。
Step 22. poll
这是一个Linux系统的文件操作系统调用，它用来查询指定的文件列表是否有有可读写的，如果有，就马上返回，否则的话，就阻塞线程，并等待驱动程序唤醒，重新调用poll函数，或超时返回。在我们的这个场景中，就是要查询是否有键盘事件发生，如果有的话，就返回，否则的话，当前线程就睡眠等待键盘事件的发生了。
这样，InputManager的启动过程就分析完了，下面我们再分析应用程序注册键盘消息接收通道的过程。
2. 应用程序注册键盘消息接收通道的过程分析
InputManager启动以后，就开始负责监控键盘输入事件了。当InputManager监控到键盘输入事件时，它应该把这个键盘事件分发给谁呢？当然是要把这个键盘消息分发给当前激活的Activity窗口了，不过，当前激活的Activity窗口还需要主动注册一个键盘消息接收通道到InputManager中去，InputManager才能把这个键盘消息分发给它处理。那么，当前被激活的Activity窗口又是什么时候去注册这个键盘消息接收通道的呢？在前面一篇文章Android应用程序启动过程源代码分析中，我们分析Android应用程序的启动过程时，在Step
33中分析到ActivityThread类的handleLaunchActivity函数中，我们曾经说过，当函数handleLaunchActivity调用performLaunchActivity函数来加载这个完毕应用程序的默认Activity后，再次回到handleLaunchActivity函数时，会调用handleResumeActivity函数来使这个Activity进入Resumed状态。在调用handleResumeActivity函数的过程中，ActivityThread会通过android.view.WindowManagerImpl类为该Activity创建一个ViewRoot实例，并且会通过调用ViewRoot类的setView成员函数把与该Activity关联的View设置到这个ViewRoot中去，而Activity正是通过ViewRoot类的setView成员函数来注册键盘消息接收通道的。
有了这些背影知识后，接下来，我们就可以从ViewRoot.setView函数开始分析应用程序注册键盘消息接收通道的过程了。首先看一下这个注册过程的序列图，然后再详细分析每一个步骤：
点击查看大图
Step 1. ViewRoot.setView
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
public void setView(View view, WindowManager.LayoutParams attrs,
View panelParentView) {
......
synchronized (this) {
if (mView == null) {
......
// Schedule the first layout -before- adding to the window
// manager, to make sure we do the relayout before receiving
// any other events from the system.
requestLayout();
mInputChannel = new InputChannel();
try {
res = sWindowSession.add(mWindow, mWindowAttributes,
getHostVisibility(), mAttachInfo.mContentInsets,
mInputChannel);
} catch (RemoteException e) {
......
} finally {
......
}
......
if (view instanceof RootViewSurfaceTaker) {
mInputQueueCallback =
((RootViewSurfaceTaker)view).willYouTakeTheInputQueue();
}
if (mInputQueueCallback != null) {
mInputQueue = new InputQueue(mInputChannel);
mInputQueueCallback.onInputQueueCreated(mInputQueue);
} else {
InputQueue.registerInputChannel(mInputChannel, mInputHandler,
Looper.myQueue());
}
......
}
}
}
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void requestLayout() { ...... mLayoutRequested = true; scheduleTraversals(); } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void requestLayout() { ...... mLayoutRequested = true; scheduleTraversals(); } ...... }这个函数调用了scheduleTraversals函数来进一步执行操作，由于篇幅关系，我们就不详细描述scheduleTraversals函数了，简单来说，在scheduleTraversals函数中，会通过sendEmptyMessage(DO_TRAVERSAL)发送一个消息到应用程序的消息队列中，这个消息最终由ViewRoot的handleMessage函数处理，而ViewRoot的handleMessage函数把这个消息交给ViewRoot类的performTraversals来处理，在performTraversals函数中，又会调用ViewRoot类的relayoutWindow函数来进一步执行操作，最后在relayoutWindow函数中，就会通过WindowManagerService内部类Session的远程接口sWindowSession的relayout函数来进入到WindowManagerService中。
Step 3. WindowManagerService.Session.relayout
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java 文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
private final class Session extends IWindowSession.Stub
implements IBinder.DeathRecipient {
......
public int relayout(IWindow window, WindowManager.LayoutParams attrs,
int requestedWidth, int requestedHeight, int viewFlags,
boolean insetsPending, Rect outFrame, Rect outContentInsets,
Rect outVisibleInsets, Configuration outConfig, Surface outSurface) {
//Log.d(TAG, ">>>>>> ENTERED relayout from " + Binder.getCallingPid());
int res = relayoutWindow(this, window, attrs,
requestedWidth, requestedHeight, viewFlags, insetsPending,
outFrame, outContentInsets, outVisibleInsets, outConfig, outSurface);
//Log.d(TAG, "<<<<<< EXITING relayout to " + Binder.getCallingPid());
return res;
}
......
}
......
}
view plaincopy to clipboardprint? public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public int relayoutWindow(Session session, IWindow client, WindowManager.LayoutParams attrs, int requestedWidth, int requestedHeight, int viewVisibility, boolean insetsPending, Rect outFrame, Rect outContentInsets, Rect outVisibleInsets, Configuration outConfig, Surface outSurface) { ...... synchronized(mWindowMap) { ...... mInputMonitor.updateInputWindowsLw(); } ...... } ...... } public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public int relayoutWindow(Session session, IWindow client, WindowManager.LayoutParams attrs, int requestedWidth, int requestedHeight, int viewVisibility, boolean insetsPending, Rect outFrame, Rect outContentInsets, Rect outVisibleInsets, Configuration outConfig, Surface outSurface) { ...... synchronized(mWindowMap) { ...... mInputMonitor.updateInputWindowsLw(); } ...... } ...... }这个函数又会继续调用mInputMonitor的updateInputWindowsLw成员函数来更新当前的输入窗口，mInputMonitor是WindowManagerService的成员变量，它的类型为InputMonitor。
Step 5. InputMonitor.updateInputWindowsLw
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java 文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
final class InputMonitor {
......
/* Updates the cached window information provided to the input dispatcher. */
public void updateInputWindowsLw() {
// Populate the input window list with information about all of the windows that
// could potentially receive input.
// As an optimization, we could try to prune the list of windows but this turns
// out to be difficult because only the native code knows for sure which window
// currently has touch focus.
final ArrayList<WindowState> windows = mWindows;
final int N = windows.size();
for (int i = N - 1; i >= 0; i--) {
final WindowState child = windows.get(i);
if (child.mInputChannel == null || child.mRemoved) {
// Skip this window because it cannot possibly receive input.
continue;
}
......
// Add a window to our list of input windows.
final InputWindow inputWindow = mTempInputWindows.add();
......
}
// Send windows to native code.
mInputManager.setInputWindows(mTempInputWindows.toNullTerminatedArray());
......
}
......
}
......
}
view plaincopy to clipboardprint? public class InputManager { ...... public void setInputWindows(InputWindow[] windows) { nativeSetInputWindows(windows); } ...... } public class InputManager { ...... public void setInputWindows(InputWindow[] windows) { nativeSetInputWindows(windows); } ...... }这个函数调用了本地方法nativeSetInputWindows来进一步执行操作。
Step 7. InputManager.nativeSetInputWindows
这个函数定义在frameworks/base/services/jni/com_android_server_InputManager.cpp 文件中：
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static void android_server_InputManager_nativeSetInputWindows(JNIEnv* env, jclass clazz,
jobjectArray windowObjArray) {
if (checkInputManagerUnitialized(env)) {
return;
}
gNativeInputManager->setInputWindows(env, windowObjArray);
}
view plaincopy to clipboardprint? void NativeInputManager::setInputWindows(JNIEnv* env, jobjectArray windowObjArray) { Vector<InputWindow> windows; jsize length = env->GetArrayLength(windowObjArray); for (jsize i = 0; i < length; i++) { jobject inputTargetObj = env->GetObjectArrayElement(windowObjArray, i); if (! inputTargetObj) { break; // found null element indicating end of used portion of the array } windows.push(); InputWindow& window = windows.editTop(); bool valid = populateWindow(env, inputTargetObj, window); if (! valid) { windows.pop(); } env->DeleteLocalRef(inputTargetObj); } mInputManager->getDispatcher()->setInputWindows(windows); } void NativeInputManager::setInputWindows(JNIEnv* env, jobjectArray windowObjArray) { Vector<InputWindow> windows; jsize length = env->GetArrayLength(windowObjArray); for (jsize i = 0; i < length; i++) { jobject inputTargetObj = env->GetObjectArrayElement(windowObjArray, i); if (! inputTargetObj) { break; // found null element indicating end of used portion of the array } windows.push(); InputWindow& window = windows.editTop(); bool valid = populateWindow(env, inputTargetObj, window); if (! valid) { windows.pop(); } env->DeleteLocalRef(inputTargetObj); } mInputManager->getDispatcher()->setInputWindows(windows); }这个函数首先将Java层的Window转换成C++层的InputWindow，然后放在windows向量中，最后将这些输入窗口设置到InputDispatcher中去。
Step 9. InputDispatcher.setInputWindows
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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void InputDispatcher::setInputWindows(const Vector<InputWindow>& inputWindows) {
......
{ // acquire lock
AutoMutex _l(mLock);
// Clear old window pointers.
sp<InputChannel> oldFocusedWindowChannel;
if (mFocusedWindow) {
oldFocusedWindowChannel = mFocusedWindow->inputChannel;
mFocusedWindow = NULL;
}
mWindows.clear();
// Loop over new windows and rebuild the necessary window pointers for
// tracking focus and touch.
mWindows.appendVector(inputWindows);
size_t numWindows = mWindows.size();
for (size_t i = 0; i < numWindows; i++) {
const InputWindow* window = & mWindows.itemAt(i);
if (window->hasFocus) {
mFocusedWindow = window;
break;
}
}
......
} // release lock
......
}
view plaincopy to clipboardprint? mInputChannel = new InputChannel(); try { res = sWindowSession.add(mWindow, mWindowAttributes, getHostVisibility(), mAttachInfo.mContentInsets, mInputChannel); } catch (RemoteException e) { ...... } finally { ...... } mInputChannel = new InputChannel(); try { res = sWindowSession.add(mWindow, mWindowAttributes, getHostVisibility(), mAttachInfo.mContentInsets, mInputChannel); } catch (RemoteException e) { ...... } finally { ...... }前面说过，这里的sWindowSession是WindowManagerService内部类Session的一个远程接口，通过它可以进入到WindowManagerService中去。
Step 10. WindowManagerService.Session.add
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java 文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
private final class Session extends IWindowSession.Stub
implements IBinder.DeathRecipient {
......
public int add(IWindow window, WindowManager.LayoutParams attrs,
int viewVisibility, Rect outContentInsets, InputChannel outInputChannel) {
return addWindow(this, window, attrs, viewVisibility, outContentInsets,
outInputChannel);
}
......
}
......
}
view plaincopy to clipboardprint? public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public int addWindow(Session session, IWindow client, WindowManager.LayoutParams attrs, int viewVisibility, Rect outContentInsets, InputChannel outInputChannel) { ...... WindowState win = null; synchronized(mWindowMap) { ...... win = new WindowState(session, client, token, attachedWindow, attrs, viewVisibility); ...... if (outInputChannel != null) { String name = win.makeInputChannelName(); InputChannel[] inputChannels = InputChannel.openInputChannelPair(name); win.mInputChannel = inputChannels[0]; inputChannels[1].transferToBinderOutParameter(outInputChannel); mInputManager.registerInputChannel(win.mInputChannel); } ...... } ...... } ...... } public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public int addWindow(Session session, IWindow client, WindowManager.LayoutParams attrs, int viewVisibility, Rect outContentInsets, InputChannel outInputChannel) { ...... WindowState win = null; synchronized(mWindowMap) { ...... win = new WindowState(session, client, token, attachedWindow, attrs, viewVisibility); ...... if (outInputChannel != null) { String name = win.makeInputChannelName(); InputChannel[] inputChannels = InputChannel.openInputChannelPair(name); win.mInputChannel = inputChannels[0]; inputChannels[1].transferToBinderOutParameter(outInputChannel); mInputManager.registerInputChannel(win.mInputChannel); } ...... } ...... } ...... }
这里的outInputChannel即为前面在Step 1中创建的InputChannel，它不为NULL，因此，这里会通过InputChannel.openInputChannelPair函数来创建一对输入通道，其中一个位于WindowManagerService中，另外一个通过outInputChannel参数返回到应用程序中：
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inputChannels[1].transferToBinderOutParameter(outInputChannel);
view plaincopy to clipboardprint? win.mInputChannel = inputChannels[0]; win.mInputChannel = inputChannels[0];
接下来我们就看一下InputChannel.openInputChannelPair函数的实现。
Step 12. InputChannel.openInputChannelPair
这个函数定义在frameworks/base/core/java/android/view/InputChannel.java文件中：
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public final class InputChannel implements Parcelable {
......
/**
* Creates a new input channel pair. One channel should be provided to the input
* dispatcher and the other to the application's input queue.
* @param name The descriptive (non-unique) name of the channel pair.
* @return A pair of input channels. They are symmetric and indistinguishable.
*/
public static InputChannel[] openInputChannelPair(String name) {
......
return nativeOpenInputChannelPair(name);
}
......
}
view plaincopy to clipboardprint? static jobjectArray android_view_InputChannel_nativeOpenInputChannelPair(JNIEnv* env, jclass clazz, jstring nameObj) { const char* nameChars = env->GetStringUTFChars(nameObj, NULL); String8 name(nameChars); env->ReleaseStringUTFChars(nameObj, nameChars); sp<InputChannel> serverChannel; sp<InputChannel> clientChannel; status_t result = InputChannel::openInputChannelPair(name, serverChannel, clientChannel); if (result) { LOGE("Could not open input channel pair. status=%d", result); jniThrowRuntimeException(env, "Could not open input channel pair."); return NULL; } // TODO more robust error checking jobject serverChannelObj = android_view_InputChannel_createInputChannel(env, new NativeInputChannel(serverChannel)); jobject clientChannelObj = android_view_InputChannel_createInputChannel(env, new NativeInputChannel(clientChannel)); jobjectArray channelPair = env->NewObjectArray(2, gInputChannelClassInfo.clazz, NULL); env->SetObjectArrayElement(channelPair, 0, serverChannelObj); env->SetObjectArrayElement(channelPair, 1, clientChannelObj); return channelPair; } static jobjectArray android_view_InputChannel_nativeOpenInputChannelPair(JNIEnv* env, jclass clazz, jstring nameObj) { const char* nameChars = env->GetStringUTFChars(nameObj, NULL); String8 name(nameChars); env->ReleaseStringUTFChars(nameObj, nameChars); sp<InputChannel> serverChannel; sp<InputChannel> clientChannel; status_t result = InputChannel::openInputChannelPair(name, serverChannel, clientChannel); if (result) { LOGE("Could not open input channel pair. status=%d", result); jniThrowRuntimeException(env, "Could not open input channel pair."); return NULL; } // TODO more robust error checking jobject serverChannelObj = android_view_InputChannel_createInputChannel(env, new NativeInputChannel(serverChannel)); jobject clientChannelObj = android_view_InputChannel_createInputChannel(env, new NativeInputChannel(clientChannel)); jobjectArray channelPair = env->NewObjectArray(2, gInputChannelClassInfo.clazz, NULL); env->SetObjectArrayElement(channelPair, 0, serverChannelObj); env->SetObjectArrayElement(channelPair, 1, clientChannelObj); return channelPair; }这个函数根据传进来的参数name在C++层分别创建两个InputChannel，一个作为Server端使用，一个作为Client端使用，这里的Server端即是指InputManager，而Client端即是指应用程序。这两个本地的InputChannel是通过InputChannel::openInputChannelPair函数创建的，创建完成后，再相应地在Java层创建相应的两个InputChannel，然后返回。
Step 14. InputChannel.openInputChannelPair
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputChannel::openInputChannelPair(const String8& name,
sp<InputChannel>& outServerChannel, sp<InputChannel>& outClientChannel) {
status_t result;
int serverAshmemFd = ashmem_create_region(name.string(), DEFAULT_MESSAGE_BUFFER_SIZE);
if (serverAshmemFd < 0) {
......
} else {
result = ashmem_set_prot_region(serverAshmemFd, PROT_READ | PROT_WRITE);
if (result < 0) {
......
} else {
// Dup the file descriptor because the server and client input channel objects that
// are returned may have different lifetimes but they share the same shared memory region.
int clientAshmemFd;
clientAshmemFd = dup(serverAshmemFd);
if (clientAshmemFd < 0) {
......
} else {
int forward[2];
if (pipe(forward)) {
......
} else {
int reverse[2];
if (pipe(reverse)) {
......
} else {
String8 serverChannelName = name;
serverChannelName.append(" (server)");
outServerChannel = new InputChannel(serverChannelName,
serverAshmemFd, reverse[0], forward[1]);
String8 clientChannelName = name;
clientChannelName.append(" (client)");
outClientChannel = new InputChannel(clientChannelName,
clientAshmemFd, forward[0], reverse[1]);
return OK;
}
......
}
......
}
}
}
......
}
view plaincopy to clipboardprint? InputChannel::InputChannel(const String8& name, int32_t ashmemFd, int32_t receivePipeFd, int32_t sendPipeFd) : mName(name), mAshmemFd(ashmemFd), mReceivePipeFd(receivePipeFd), mSendPipeFd(sendPipeFd) { ...... } InputChannel::InputChannel(const String8& name, int32_t ashmemFd, int32_t receivePipeFd, int32_t sendPipeFd) : mName(name), mAshmemFd(ashmemFd), mReceivePipeFd(receivePipeFd), mSendPipeFd(sendPipeFd) { ...... }为了创建一个InputChannel，我们需要准备四个参数，一个是输入通道的名称name，一个是匿名共享内存文件描述符，一个是管道的读端文件描述符，一个是管道的写端文件描述符。在上面的openInputChannelPair函数，输入通道的名称已经作为参数传递进来，因此，还需要创建匿名共享内存文件，还有管道。这里需要创建两个管道，一个称为前向管道（forward
pipe），一个称为反向管道（reverse pipe），它们交叉使用在Server端和Client端的InputChannel中，这样就使入Server和Client可以互相通信了。
具体来说，Server端和Client端的InputChannel分别是这样构成的：
Server Input Channel: ashmem - reverse(read) - forward(write)
Client Input Channel: ashmem - forward(read) - reverse(write)
前面我们在Android应用程序消息处理机制（Looper、Handler）分析一文中学习Android应用程序的消息处理机制时知道，管道可以用作进程间通信，其中一个进程在管道的读端等待新的内空可读，另一个进程在管道的写端写入新的内容以唤醒在管道读端等待的进程，这样就实现了进程间通信。在我们这个情景中，Client端可以在前向管道（forward pipe）的读端睡眠等待新的内容可读，而Server端可以通过向前向管道（forward
pipe）的写端写入新的内容来唤醒Client端，同样，把前向管道（forward pipe）换成反向管道（reverse pipe），也能实现Client端唤醒Server端。在后面我们分析InputDispatcher分发键盘消息时，会看到它们的用法。
有了这些背景知识后，相信上面的openInputChannelPair的代码就容易理解了，这里就不再详述了。
创建好了这两个输入通道后，回到Step 11中的WindowManagerService.addWindow函数中，一方面它把刚才创建的Client端的输入通道通过outInputChannel参数返回到应用程序中：
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inputChannels[1].transferToBinderOutParameter(outInputChannel);
view plaincopy to clipboardprint? mInputManager.registerInputChannel(win.mInputChannel); mInputManager.registerInputChannel(win.mInputChannel);Step 15. InputManager.registerInputChannel
这个函数定义在frameworks/base/services/java/com/android/server/InputManager.java文件中：
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public class InputManager {
......
/**
* Registers an input channel so that it can be used as an input event target.
* @param inputChannel The input channel to register.
*/
public void registerInputChannel(InputChannel inputChannel) {
if (inputChannel == null) {
throw new IllegalArgumentException("inputChannel must not be null.");
}
nativeRegisterInputChannel(inputChannel, false);
}
......
}
view plaincopy to clipboardprint? static void android_server_InputManager_nativeRegisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj, jboolean monitor) { ...... sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env, inputChannelObj); ...... status_t status = gNativeInputManager->registerInputChannel( env, inputChannel, inputChannelObj, monitor); ...... } static void android_server_InputManager_nativeRegisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj, jboolean monitor) { ...... sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env, inputChannelObj); ...... status_t status = gNativeInputManager->registerInputChannel( env, inputChannel, inputChannelObj, monitor); ...... }这里首先通过Java层的InputChannel对象获得C++层的InputChannel对象，它们之间的对应关系是在前面的Step 13中设置好的，接着调用NativeInputManager的registerInputChannel执行进一步的操作。
Step 17. NativeInputManager.registerInputChannel
这个函数定义在frameworks/base/services/jni/com_android_server_InputManager.cpp 文件中：
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status_t NativeInputManager::registerInputChannel(JNIEnv* env,
const sp<InputChannel>& inputChannel, jobject inputChannelObj, bool monitor) {
......
status = mInputManager->getDispatcher()->registerInputChannel(inputChannel, monitor);
......
}
view plaincopy to clipboardprint? status_t InputDispatcher::registerInputChannel(const sp<InputChannel>& inputChannel, bool monitor) { ...... { // acquire lock AutoMutex _l(mLock); if (getConnectionIndexLocked(inputChannel) >= 0) { LOGW("Attempted to register already registered input channel '%s'", inputChannel->getName().string()); return BAD_VALUE; } sp<Connection> connection = new Connection(inputChannel); status_t status = connection->initialize(); if (status) { LOGE("Failed to initialize input publisher for input channel '%s', status=%d", inputChannel->getName().string(), status); return status; } int32_t receiveFd = inputChannel->getReceivePipeFd(); mConnectionsByReceiveFd.add(receiveFd, connection); if (monitor) { mMonitoringChannels.push(inputChannel); } mLooper->addFd(receiveFd, 0, ALOOPER_EVENT_INPUT, handleReceiveCallback, this); runCommandsLockedInterruptible(); } // release lock return OK; } status_t InputDispatcher::registerInputChannel(const sp<InputChannel>& inputChannel, bool monitor) { ...... { // acquire lock AutoMutex _l(mLock); if (getConnectionIndexLocked(inputChannel) >= 0) { LOGW("Attempted to register already registered input channel '%s'", inputChannel->getName().string()); return BAD_VALUE; } sp<Connection> connection = new Connection(inputChannel); status_t status = connection->initialize(); if (status) { LOGE("Failed to initialize input publisher for input channel '%s', status=%d", inputChannel->getName().string(), status); return status; } int32_t receiveFd = inputChannel->getReceivePipeFd(); mConnectionsByReceiveFd.add(receiveFd, connection); if (monitor) { mMonitoringChannels.push(inputChannel); } mLooper->addFd(receiveFd, 0, ALOOPER_EVENT_INPUT, handleReceiveCallback, this); runCommandsLockedInterruptible(); } // release lock return OK; }这个函数首先会通过getConnectionIndexLocked检查从参数传进来的InputChannel是否已经注册过了，如果已经注册过了，就返回一个BAD_VALUE值了，否则的话，就会创建一个Connection对象来封装即将要注册的inputChannel，我们可以不关心这个Connection对象的实现，接着还通过调用inputChannel->getReceivePipeFd获得一个管
道的读端描述符。回忆一下Step 14中的InputChannel.openInputChannelPair函数，我们创建了一个Server端的InputChannel，就是对应这里的inputChannel了，这个inputChannel的Receive Pipe Fd就是我们前面说的反向管道的读端描述符了。有了这个Receive Pipe Fd后，就以它作为Key值来把前面创建的Connection对象保存在InputDispatcher中，这样就基本完成键盘消息接收通道的注册了。但是，注册的工作还未完成，最后，还要把这个Receive
Pipe Fd添加到InputDispatcher的成员变量mLooper中去，这里的成员变量mLooper的类型为Looper，我们在前面介绍InputManager的启动过程的Step 15中已经见过了，这里就不再详述了，不过这里仍然值得介绍一下它的addFd函数。
在前面一篇文章Android应用程序消息处理机制（Looper、Handler）分析中，我们在介绍到Android应用程序的消息循环一节时，曾经说过，在Looper类内部，会创建一个管道，然后Looper会睡眠在这个管道的读端，等待另外一个线程来往这个管道的写端写入新的内容，从而唤醒等待在这个管道读端的线程，除此之外，Looper还可以同时睡眠等待在其它的文件描述符上，因为它是通过Linux系统的epoll机制来批量等待指定的文件有新的内容可读的。这些其它的文件描述符就是通过Looper类的addFd成函数添加进去的了，在添加的时候，还可以指定回调函数，即当这个文件描述符所指向的文件有新的内容可读时，Looper就会调用这个hanldeReceiveCallback函数，有兴趣的读者可以自己研究一下Looper类的addFd函数的实现，它位于frameworks/base/libs/utils/Looper.cpp文件中。
分析到这里，Server端的InputChannel就注册完成了。回忆一下前面介绍InputManager启动过程的Step 14，这时InputDispatcherThread同时睡眠在InputDispatcher的成员变量mLooper内部的管道的读端以及这里的Server端InputChannel里面的反向管道的读端上，mLooper内部的管道的读端等待键盘事件的发生而被唤醒，而Server端InputChannel里面的反向管道的读端等待Client端InputChannel里面的反向管道的写端被写入新的内容而被唤醒。
Server端的InputChannel注册完成后，回到Step 11中的WindowManagerService.addWindow函数，接下来就是把Client端的InputChannel转换成addWindow的参数outInputChannel中，然后返回到Step 1中的ViewRoot.setView函数中，继续执行Client端的InputChannel的注册过程，即为应用程序这一侧注册键盘消息接收通道：
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if (view instanceof RootViewSurfaceTaker) {
mInputQueueCallback =
((RootViewSurfaceTaker)view).willYouTakeTheInputQueue();
}
if (mInputQueueCallback != null) {
mInputQueue = new InputQueue(mInputChannel);
mInputQueueCallback.onInputQueueCreated(mInputQueue);
} else {
InputQueue.registerInputChannel(mInputChannel, mInputHandler,
Looper.myQueue());
}
view plaincopy to clipboardprint? InputQueue.registerInputChannel(mInputChannel, mInputHandler, Looper.myQueue()); InputQueue.registerInputChannel(mInputChannel, mInputHandler, Looper.myQueue());它调用InputQueue的registerInputChannel函数为应用程序注册键盘消息接收通道，这里的mInputChannel即为我们在前面Step 14中创建的Client端的InputChannel；Looper.myQueue函数返回的便是应用程序主线程的消息队列，具体可以参考前面一篇文章Android应用程序消息处理机制（Looper、Handler）分析；参数mInputHandler是一个回调对象，当有键盘事件发生时，这个mInputHandler的handleKey函数就会被调用，在后面的分析中，我们将会看到。
Step 19. InputQueue.registerInputChannel
这个函数定义在frameworks/base/core/java/android/view/InputQueue.java文件中：
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public final class InputQueue {
......
public static void registerInputChannel(InputChannel inputChannel, InputHandler inputHandler,
MessageQueue messageQueue) {
......
synchronized (sLock) {
......
nativeRegisterInputChannel(inputChannel, inputHandler, messageQueue);
}
}
......
}
view plaincopy to clipboardprint? static void android_view_InputQueue_nativeRegisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj, jobject inputHandlerObj, jobject messageQueueObj) { status_t status = gNativeInputQueue.registerInputChannel( env, inputChannelObj, inputHandlerObj, messageQueueObj); ...... } static void android_view_InputQueue_nativeRegisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj, jobject inputHandlerObj, jobject messageQueueObj) { status_t status = gNativeInputQueue.registerInputChannel( env, inputChannelObj, inputHandlerObj, messageQueueObj); ...... }这里继续调用NativeInputQueue的registerInputChannel函数来执行真正的键盘消息接收通道的工作。
Step 21. NativeInputQueue.registerInputChannel
这个函数定义在frameworks/base/core/jni/android_view_InputQueue.cpp文件中：
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status_t NativeInputQueue::registerInputChannel(JNIEnv* env, jobject inputChannelObj,
jobject inputHandlerObj, jobject messageQueueObj) {
sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env,
inputChannelObj);
......
sp<Looper> looper = android_os_MessageQueue_getLooper(env, messageQueueObj);
{ // acquire lock
AutoMutex _l(mLock);
if (getConnectionIndex(inputChannel) >= 0) {
LOGW("Attempted to register already registered input channel '%s'",
inputChannel->getName().string());
return BAD_VALUE;
}
uint16_t connectionId = mNextConnectionId++;
sp<Connection> connection = new Connection(connectionId, inputChannel, looper);
status_t result = connection->inputConsumer.initialize();
if (result) {
LOGW("Failed to initialize input consumer for input channel '%s', status=%d",
inputChannel->getName().string(), result);
return result;
}
connection->inputHandlerObjGlobal = env->NewGlobalRef(inputHandlerObj);
int32_t receiveFd = inputChannel->getReceivePipeFd();
mConnectionsByReceiveFd.add(receiveFd, connection);
looper->addFd(receiveFd, 0, ALOOPER_EVENT_INPUT, handleReceiveCallback, this);
} // release lock
......
return OK;
}
view plaincopy to clipboardprint? void InputReader::loopOnce() { RawEvent rawEvent; mEventHub->getEvent(& rawEvent); ...... process(& rawEvent); } void InputReader::loopOnce() { RawEvent rawEvent; mEventHub->getEvent(& rawEvent); ...... process(& rawEvent); }Step 3. InputReader.process
这个函数定义在frameworks/base/libs/ui/InputReader.cpp文件中：
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void InputReader::process(const RawEvent* rawEvent) {
switch (rawEvent->type) {
case EventHubInterface::DEVICE_ADDED:
addDevice(rawEvent->deviceId);
break;
case EventHubInterface::DEVICE_REMOVED:
removeDevice(rawEvent->deviceId);
break;
case EventHubInterface::FINISHED_DEVICE_SCAN:
handleConfigurationChanged(rawEvent->when);
break;
default:
consumeEvent(rawEvent);
break;
}
}
view plaincopy to clipboardprint? #define EV_KEY 0x01 #define EV_KEY 0x01因此，接下来会调用consumeEvent函数进一步处理。
Step 4. InputReader.consumeEvent
这个函数定义在frameworks/base/libs/ui/InputReader.cpp文件中：
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void InputReader::consumeEvent(const RawEvent* rawEvent) {
int32_t deviceId = rawEvent->deviceId;
{ // acquire device registry reader lock
RWLock::AutoRLock _rl(mDeviceRegistryLock);
ssize_t deviceIndex = mDevices.indexOfKey(deviceId);
if (deviceIndex < 0) {
LOGW("Discarding event for unknown deviceId %d.", deviceId);
return;
}
InputDevice* device = mDevices.valueAt(deviceIndex);
if (device->isIgnored()) {
//LOGD("Discarding event for ignored deviceId %d.", deviceId);
return;
}
device->process(rawEvent);
} // release device registry reader lock
}
view plaincopy to clipboardprint? void InputDevice::process(const RawEvent* rawEvent) { size_t numMappers = mMappers.size(); for (size_t i = 0; i < numMappers; i++) { InputMapper* mapper = mMappers[i]; mapper->process(rawEvent); } } void InputDevice::process(const RawEvent* rawEvent) { size_t numMappers = mMappers.size(); for (size_t i = 0; i < numMappers; i++) { InputMapper* mapper = mMappers[i]; mapper->process(rawEvent); } }这里的mMapper成员变量保存了一系列输入设备事件处理象，例如负责处理键盘事件的KeyboardKeyMapper对象、负责处理轨迹球事件的TrackballInputMapper对象以及负责处理触摸屏事件的TouchInputMapper对象， 它们是在InputReader类的成员函数createDevice中创建的。这里查询每一个InputMapper对象是否要对当前发生的事件进行处理。由于发生的是键盘事件，真正会对该事件进行处理的只有KeyboardKeyMapper对象。
Step 6. KeyboardInputMapper.process
这个函数定义在frameworks/base/libs/ui/InputReader.cpp文件中：
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void KeyboardInputMapper::process(const RawEvent* rawEvent) {
switch (rawEvent->type) {
case EV_KEY: {
int32_t scanCode = rawEvent->scanCode;
if (isKeyboardOrGamepadKey(scanCode)) {
processKey(rawEvent->when, rawEvent->value != 0, rawEvent->keyCode, scanCode,
rawEvent->flags);
}
break;
}
}
}
view plaincopy to clipboardprint? void KeyboardInputMapper::processKey(nsecs_t when, bool down, int32_t keyCode, int32_t scanCode, uint32_t policyFlags) { int32_t newMetaState; nsecs_t downTime; bool metaStateChanged = false; { // acquire lock AutoMutex _l(mLock); if (down) { // Rotate key codes according to orientation if needed. // Note: getDisplayInfo is non-reentrant so we can continue holding the lock. if (mAssociatedDisplayId >= 0) { int32_t orientation; if (! getPolicy()->getDisplayInfo(mAssociatedDisplayId, NULL, NULL, & orientation)) { return; } keyCode = rotateKeyCode(keyCode, orientation); } // Add key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key repeat, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; } else { // key down if ((policyFlags & POLICY_FLAG_VIRTUAL) && mContext->shouldDropVirtualKey(when, getDevice(), keyCode, scanCode)) { return; } mLocked.keyDowns.push(); KeyDown& keyDown = mLocked.keyDowns.editTop(); keyDown.keyCode = keyCode; keyDown.scanCode = scanCode; } mLocked.downTime = when; } else { // Remove key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key up, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; mLocked.keyDowns.removeAt(size_t(keyDownIndex)); } else { // key was not actually down LOGI("Dropping key up from device %s because the key was not down. " "keyCode=%d, scanCode=%d", getDeviceName().string(), keyCode, scanCode); return; } } int32_t oldMetaState = mLocked.metaState; newMetaState = updateMetaState(keyCode, down, oldMetaState); if (oldMetaState != newMetaState) { mLocked.metaState = newMetaState; metaStateChanged = true; } downTime = mLocked.downTime; } // release lock if (metaStateChanged) { getContext()->updateGlobalMetaState(); } getDispatcher()->notifyKey(when, getDeviceId(), AINPUT_SOURCE_KEYBOARD, policyFlags, down ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP, AKEY_EVENT_FLAG_FROM_SYSTEM, keyCode, scanCode, newMetaState, downTime); } void KeyboardInputMapper::processKey(nsecs_t when, bool down, int32_t keyCode, int32_t scanCode, uint32_t policyFlags) { int32_t newMetaState; nsecs_t downTime; bool metaStateChanged = false; { // acquire lock AutoMutex _l(mLock); if (down) { // Rotate key codes according to orientation if needed. // Note: getDisplayInfo is non-reentrant so we can continue holding the lock. if (mAssociatedDisplayId >= 0) { int32_t orientation; if (! getPolicy()->getDisplayInfo(mAssociatedDisplayId, NULL, NULL, & orientation)) { return; } keyCode = rotateKeyCode(keyCode, orientation); } // Add key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key repeat, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; } else { // key down if ((policyFlags & POLICY_FLAG_VIRTUAL) && mContext->shouldDropVirtualKey(when, getDevice(), keyCode, scanCode)) { return; } mLocked.keyDowns.push(); KeyDown& keyDown = mLocked.keyDowns.editTop(); keyDown.keyCode = keyCode; keyDown.scanCode = scanCode; } mLocked.downTime = when; } else { // Remove key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key up, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; mLocked.keyDowns.removeAt(size_t(keyDownIndex)); } else { // key was not actually down LOGI("Dropping key up from device %s because the key was not down. " "keyCode=%d, scanCode=%d", getDeviceName().string(), keyCode, scanCode); return; } } int32_t oldMetaState = mLocked.metaState; newMetaState = updateMetaState(keyCode, down, oldMetaState); if (oldMetaState != newMetaState) { mLocked.metaState = newMetaState; metaStateChanged = true; } downTime = mLocked.downTime; } // release lock if (metaStateChanged) { getContext()->updateGlobalMetaState(); } getDispatcher()->notifyKey(when, getDeviceId(), AINPUT_SOURCE_KEYBOARD, policyFlags, down ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP, AKEY_EVENT_FLAG_FROM_SYSTEM, keyCode, scanCode, newMetaState, downTime); }这个函数首先对对按键作一些处理，例如，当某一个DPAD键被按下时，根据当时屏幕方向的不同，它所表示的意义也不同，因此，这里需要根据当时屏幕的方向来调整键盘码：
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// Rotate key codes according to orientation if needed.
// Note: getDisplayInfo is non-reentrant so we can continue holding the lock.
if (mAssociatedDisplayId >= 0) {
int32_t orientation;
if (! getPolicy()->getDisplayInfo(mAssociatedDisplayId, NULL, NULL, & orientation)) {
return;
}
keyCode = rotateKeyCode(keyCode, orientation);
}
view plaincopy to clipboardprint? // Add key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key repeat, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; } else { // key down if ((policyFlags & POLICY_FLAG_VIRTUAL) && mContext->shouldDropVirtualKey(when, getDevice(), keyCode, scanCode)) { return; } mLocked.keyDowns.push(); KeyDown& keyDown = mLocked.keyDowns.editTop(); keyDown.keyCode = keyCode; keyDown.scanCode = scanCode; } // Add key down. ssize_t keyDownIndex = findKeyDownLocked(scanCode); if (keyDownIndex >= 0) { // key repeat, be sure to use same keycode as before in case of rotation keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode; } else { // key down if ((policyFlags & POLICY_FLAG_VIRTUAL) && mContext->shouldDropVirtualKey(when, getDevice(), keyCode, scanCode)) { return; } mLocked.keyDowns.push(); KeyDown& keyDown = mLocked.keyDowns.editTop(); keyDown.keyCode = keyCode; keyDown.scanCode = scanCode; }如果是第一次按下某个键，还必须把它保存在mLocked.keyDowns里面，就是为了处理上面讲的当这个键盘一直按着不放的时候屏幕方向发生改变的情况。
如果是松开键盘上的某个键，就把它从mLocked.keyDowns里面删除：
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// Remove key down.
ssize_t keyDownIndex = findKeyDownLocked(scanCode);
if (keyDownIndex >= 0) {
// key up, be sure to use same keycode as before in case of rotation
keyCode = mLocked.keyDowns.itemAt(keyDownIndex).keyCode;
mLocked.keyDowns.removeAt(size_t(keyDownIndex));
} else {
// key was not actually down
LOGI("Dropping key up from device %s because the key was not down. "
"keyCode=%d, scanCode=%d",
getDeviceName().string(), keyCode, scanCode);
return;
}
view plaincopy to clipboardprint? getDispatcher()->notifyKey(when, getDeviceId(), AINPUT_SOURCE_KEYBOARD, policyFlags, down ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP, AKEY_EVENT_FLAG_FROM_SYSTEM, keyCode, scanCode, newMetaState, downTime); getDispatcher()->notifyKey(when, getDeviceId(), AINPUT_SOURCE_KEYBOARD, policyFlags, down ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP, AKEY_EVENT_FLAG_FROM_SYSTEM, keyCode, scanCode, newMetaState, downTime);Step 8. InputDispatcher.notifyKey
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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void InputDispatcher::notifyKey(nsecs_t eventTime, int32_t deviceId, int32_t source,
uint32_t policyFlags, int32_t action, int32_t flags,
int32_t keyCode, int32_t scanCode, int32_t metaState, nsecs_t downTime) {
......
if (! validateKeyEvent(action)) {
return;
}
/* According to http://source.android.com/porting/keymaps_keyboard_input.html
* Key definitions: Key definitions follow the syntax key SCANCODE KEYCODE [FLAGS...],
* where SCANCODE is a number, KEYCODE is defined in your specific keylayout file
* (android.keylayout.xxx), and potential FLAGS are defined as follows:
* SHIFT: While pressed, the shift key modifier is set
* ALT: While pressed, the alt key modifier is set
* CAPS: While pressed, the caps lock key modifier is set
* Since KeyEvent.java doesn't check if Cap lock is ON and we don't have a
* modifer state for cap lock, we will not support it.
*/
if (policyFlags & POLICY_FLAG_ALT) {
metaState |= AMETA_ALT_ON | AMETA_ALT_LEFT_ON;
}
if (policyFlags & POLICY_FLAG_ALT_GR) {
metaState |= AMETA_ALT_ON | AMETA_ALT_RIGHT_ON;
}
if (policyFlags & POLICY_FLAG_SHIFT) {
metaState |= AMETA_SHIFT_ON | AMETA_SHIFT_LEFT_ON;
}
policyFlags |= POLICY_FLAG_TRUSTED;
mPolicy->interceptKeyBeforeQueueing(eventTime, deviceId, action, /*byref*/ flags,
keyCode, scanCode, /*byref*/ policyFlags);
bool needWake;
{ // acquire lock
AutoMutex _l(mLock);
int32_t repeatCount = 0;
KeyEntry* newEntry = mAllocator.obtainKeyEntry(eventTime,
deviceId, source, policyFlags, action, flags, keyCode, scanCode,
metaState, repeatCount, downTime);
needWake = enqueueInboundEventLocked(newEntry);
} // release lock
if (needWake) {
mLooper->wake();
}
}
view plaincopy to clipboardprint? static bool isValidKeyAction(int32_t action) { switch (action) { case AKEY_EVENT_ACTION_DOWN: case AKEY_EVENT_ACTION_UP: return true; default: return false; } } static bool validateKeyEvent(int32_t action) { if (! isValidKeyAction(action)) { LOGE("Key event has invalid action code 0x%x", action); return false; } return true; } static bool isValidKeyAction(int32_t action) { switch (action) { case AKEY_EVENT_ACTION_DOWN: case AKEY_EVENT_ACTION_UP: return true; default: return false; } } static bool validateKeyEvent(int32_t action) { if (! isValidKeyAction(action)) { LOGE("Key event has invalid action code 0x%x", action); return false; } return true; }正确的action参数的值只能为AKEY_EVENT_ACTION_DOWN（按下）或者AKEY_EVENT_ACTION_UP（松开）。
参数action检查通过后，还通过policyFlags参数来检查一下同时是否有ALT和SHIFT键被按下：
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if (policyFlags & POLICY_FLAG_ALT) {
metaState |= AMETA_ALT_ON | AMETA_ALT_LEFT_ON;
}
if (policyFlags & POLICY_FLAG_ALT_GR) {
metaState |= AMETA_ALT_ON | AMETA_ALT_RIGHT_ON;
}
if (policyFlags & POLICY_FLAG_SHIFT) {
metaState |= AMETA_SHIFT_ON | AMETA_SHIFT_LEFT_ON;
}
view plaincopy to clipboardprint? bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) { bool needWake = mInboundQueue.isEmpty(); mInboundQueue.enqueueAtTail(entry); switch (entry->type) { case EventEntry::TYPE_KEY: { KeyEntry* keyEntry = static_cast<KeyEntry*>(entry); if (isAppSwitchKeyEventLocked(keyEntry)) { if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) { mAppSwitchSawKeyDown = true; } else if (keyEntry->action == AKEY_EVENT_ACTION_UP) { if (mAppSwitchSawKeyDown) { <span style="white-space:pre"> </span> ...... mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT; mAppSwitchSawKeyDown = false; needWake = true; } } } break; } } return needWake; } bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) { bool needWake = mInboundQueue.isEmpty(); mInboundQueue.enqueueAtTail(entry); switch (entry->type) { case EventEntry::TYPE_KEY: { KeyEntry* keyEntry = static_cast<KeyEntry*>(entry); if (isAppSwitchKeyEventLocked(keyEntry)) { if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) { mAppSwitchSawKeyDown = true; } else if (keyEntry->action == AKEY_EVENT_ACTION_UP) { if (mAppSwitchSawKeyDown) { <span style="white-space:pre"> </span> ...... mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT; mAppSwitchSawKeyDown = false; needWake = true; } } } break; } } return needWake; }从这个函数我们可以看出，在两种情况下，它的返回值为true，一是当加入该键盘事件到mInboundQueue之前，mInboundQueue为空，这表示InputDispatccherThread线程正在睡眠等待InputReaderThread线程的唤醒，因此，它返回true表示要唤醒InputDispatccherThread线程；二是加入该键盘事件到mInboundQueue之前，mInboundQueue不为空，但是此时用户按下的是Home键，按下Home键表示要切换App，我们知道，在切换App时，新的App会把它的键盘消息接收通道注册到InputDispatcher中去，并且会等待InputReader的唤醒，因此，在这种情况下，也需要返回true，表示要唤醒InputDispatccherThread线程。如果不是这两种情况，那么就说明InputDispatccherThread线程现在正在处理前面的键盘事件，不需要唤醒它。
回到前面的notifyKey函数中，根据enqueueInboundEventLocked函数的返回值来决定是否要唤醒InputDispatccherThread线程：
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if (needWake) {
mLooper->wake();
}
view plaincopy to clipboardprint? void InputDispatcher::dispatchOnce() { nsecs_t keyRepeatTimeout = mPolicy->getKeyRepeatTimeout(); nsecs_t keyRepeatDelay = mPolicy->getKeyRepeatDelay(); nsecs_t nextWakeupTime = LONG_LONG_MAX; { // acquire lock AutoMutex _l(mLock); dispatchOnceInnerLocked(keyRepeatTimeout, keyRepeatDelay, & nextWakeupTime); ...... } // release lock ...... } void InputDispatcher::dispatchOnce() { nsecs_t keyRepeatTimeout = mPolicy->getKeyRepeatTimeout(); nsecs_t keyRepeatDelay = mPolicy->getKeyRepeatDelay(); nsecs_t nextWakeupTime = LONG_LONG_MAX; { // acquire lock AutoMutex _l(mLock); dispatchOnceInnerLocked(keyRepeatTimeout, keyRepeatDelay, & nextWakeupTime); ...... } // release lock ...... }它调用dispatchOnceInnerLocked函数来进一步处理这个键盘事件。
Step 11. InputDispatcher.dispatchOnceInnerLocked
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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void InputDispatcher::dispatchOnceInnerLocked(nsecs_t keyRepeatTimeout,
nsecs_t keyRepeatDelay, nsecs_t* nextWakeupTime) {
......
// Ready to start a new event.
// If we don't already have a pending event, go grab one.
if (! mPendingEvent) {
if (mInboundQueue.isEmpty()) {
......
} else {
// Inbound queue has at least one entry.
EventEntry* entry = mInboundQueue.headSentinel.next;
......
mInboundQueue.dequeue(entry);
mPendingEvent = entry;
}
......
}
......
switch (mPendingEvent->type) {
......
case EventEntry::TYPE_KEY: {
KeyEntry* typedEntry = static_cast<KeyEntry*>(mPendingEvent);
......
done = dispatchKeyLocked(currentTime, typedEntry, keyRepeatTimeout,
&dropReason, nextWakeupTime);
break;
}
......
}
......
}
view plaincopy to clipboardprint? mInboundQueue.dequeue(entry); mPendingEvent = entry; mInboundQueue.dequeue(entry); mPendingEvent = entry;由于这里发生的是键盘事件，即mPendingEvent->type的值为EventEntry::TYPE_KEY，于是，在接下来的switch语句中就会执行dispatchKeyLocked函数来分发键盘消息。
Step 12. InputDispatcher.dispatchKeyLocked
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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bool InputDispatcher::dispatchKeyLocked(
nsecs_t currentTime, KeyEntry* entry, nsecs_t keyRepeatTimeout,
DropReason* dropReason, nsecs_t* nextWakeupTime) {
......
// Identify targets.
if (! mCurrentInputTargetsValid) {
int32_t injectionResult = findFocusedWindowTargetsLocked(currentTime,
entry, nextWakeupTime);
......
}
// Dispatch the key.
dispatchEventToCurrentInputTargetsLocked(currentTime, entry, false);
return true;
}
view plaincopy to clipboardprint? int32_t InputDispatcher::findFocusedWindowTargetsLocked(nsecs_t currentTime, const EventEntry* entry, nsecs_t* nextWakeupTime) { mCurrentInputTargets.clear(); int32_t injectionResult; // If there is no currently focused window and no focused application // then drop the event. if (! mFocusedWindow) { if (mFocusedApplication) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, NULL, nextWakeupTime); goto Unresponsive; } ...... injectionResult = INPUT_EVENT_INJECTION_FAILED; goto Failed; } // Check permissions. if (! checkInjectionPermission(mFocusedWindow, entry->injectionState)) { injectionResult = INPUT_EVENT_INJECTION_PERMISSION_DENIED; goto Failed; } // If the currently focused window is paused then keep waiting. if (mFocusedWindow->paused) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, mFocusedWindow, nextWakeupTime); goto Unresponsive; } // If the currently focused window is still working on previous events then keep waiting. if (! isWindowFinishedWithPreviousInputLocked(mFocusedWindow)) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, mFocusedWindow, nextWakeupTime); goto Unresponsive; } // Success! Output targets. injectionResult = INPUT_EVENT_INJECTION_SUCCEEDED; addWindowTargetLocked(mFocusedWindow, InputTarget::FLAG_FOREGROUND, BitSet32(0)); ...... return injectionResult; } int32_t InputDispatcher::findFocusedWindowTargetsLocked(nsecs_t currentTime, const EventEntry* entry, nsecs_t* nextWakeupTime) { mCurrentInputTargets.clear(); int32_t injectionResult; // If there is no currently focused window and no focused application // then drop the event. if (! mFocusedWindow) { if (mFocusedApplication) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, NULL, nextWakeupTime); goto Unresponsive; } ...... injectionResult = INPUT_EVENT_INJECTION_FAILED; goto Failed; } // Check permissions. if (! checkInjectionPermission(mFocusedWindow, entry->injectionState)) { injectionResult = INPUT_EVENT_INJECTION_PERMISSION_DENIED; goto Failed; } // If the currently focused window is paused then keep waiting. if (mFocusedWindow->paused) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, mFocusedWindow, nextWakeupTime); goto Unresponsive; } // If the currently focused window is still working on previous events then keep waiting. if (! isWindowFinishedWithPreviousInputLocked(mFocusedWindow)) { ...... injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplication, mFocusedWindow, nextWakeupTime); goto Unresponsive; } // Success! Output targets. injectionResult = INPUT_EVENT_INJECTION_SUCCEEDED; addWindowTargetLocked(mFocusedWindow, InputTarget::FLAG_FOREGROUND, BitSet32(0)); ...... return injectionResult; }回忆前面我们分析应用程序注册键盘消息接收通道的过程时，在Step 9中，当前处于激活状态的应用程序会通过调用InputDispatcher类setInputWindows函数把把当前获得焦点的Activity窗口设置到mFocusedWindow中去，因此，这里的mFocusedWindow不为NULL，于是，就通过了第一个if语句的检查。
第二个if语句检查权限问题，原来，这个键盘事件除了是由硬件触发的外，也可以由其它进程注入进来的，如果这个键盘事件是由其它进程注入进来的，那么entry->injectState就不为NULL，它里面包含了事件注册者的进程ID和用户ID，于是，这里就会调用checkInjectionPermission来检查这个事件注入者的进程ID和用户ID，看看它是否具有这个权限。这里我们不考虑这种情况，因此，这里的entry->injectState为NULL，于是，这个if语句的检查也通过了。
第三个if语句检查当前激活的Activity窗口是否是处于paused状态，如果是的话，也不用进一步处理了。一般情况下，当前激活的Activity窗口都是处于resumed状态的，于是，这个if语句的检查也通过了。
第四个if语句检查当前激活的Activity窗口是否还正在处理前一个键盘事件，如果是的话，那就要等待它处理完前一个键盘事件后再来处理新的键盘事件了。这里我们也假设当前激活的Activity窗口不是正在处理前面的键盘事件，因此，这个if语句的检查也通过了。
最后，就调用addWindowTargetLocked函数把当前激活的Activity窗口添加到InputDispatcher类的mCurrentInputTargets成员变量中去。
Step 14. InputDispatcher.addWindowTargetLocked
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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void InputDispatcher::addWindowTargetLocked(const InputWindow* window, int32_t targetFlags,
BitSet32 pointerIds) {
mCurrentInputTargets.push();
InputTarget& target = mCurrentInputTargets.editTop();
target.inputChannel = window->inputChannel;
target.flags = targetFlags;
target.xOffset = - window->frameLeft;
target.yOffset = - window->frameTop;
target.pointerIds = pointerIds;
}
view plaincopy to clipboardprint? void InputDispatcher::dispatchEventToCurrentInputTargetsLocked(nsecs_t currentTime, EventEntry* eventEntry, bool resumeWithAppendedMotionSample) { ...... for (size_t i = 0; i < mCurrentInputTargets.size(); i++) { const InputTarget& inputTarget = mCurrentInputTargets.itemAt(i); ssize_t connectionIndex = getConnectionIndexLocked(inputTarget.inputChannel); if (connectionIndex >= 0) { sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); prepareDispatchCycleLocked(currentTime, connection, eventEntry, & inputTarget, resumeWithAppendedMotionSample); } else { ...... } } void InputDispatcher::dispatchEventToCurrentInputTargetsLocked(nsecs_t currentTime, EventEntry* eventEntry, bool resumeWithAppendedMotionSample) { ...... for (size_t i = 0; i < mCurrentInputTargets.size(); i++) { const InputTarget& inputTarget = mCurrentInputTargets.itemAt(i); ssize_t connectionIndex = getConnectionIndexLocked(inputTarget.inputChannel); if (connectionIndex >= 0) { sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); prepareDispatchCycleLocked(currentTime, connection, eventEntry, & inputTarget, resumeWithAppendedMotionSample); } else { ...... } }这个函数的实现也比较简单，前面我们已经把当前需要接受键盘事件的Activity窗口添加到mCurrentInputTargets中去了，因此，这里就分别把它们取出来，然后调用prepareDispatchCycleLocked函数把键盘事件分发给它们处理。
前面我们在分析应用程序注册键盘消息接收通道的过程时，在Step 18中（InputDispatcher.registerInputChannel），把Server端的InputChannel封装成了一个Connection，然后以这个InputChannel中的Receive Pipe Fd作为键值把这个Connection对象保存在mConnectionsByReceiveFd中。这里，既然我们已经通过mCurrentInputTargets得到了表示当前需要接收键盘事件的Activity窗口的InputTarget对象，而且这个InputTarget对象的inputChannel就表示当初在InputDispatcher中注册的Server端InputChannel，因此，这里就可以把这个Connection对象取出来，最后调用prepareDispatchCycleLocked函数来进一步处理。
Step 16. InputDispatcher.prepareDispatchCycleLocked
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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void InputDispatcher::prepareDispatchCycleLocked(nsecs_t currentTime,
const sp<Connection>& connection, EventEntry* eventEntry, const InputTarget* inputTarget,
bool resumeWithAppendedMotionSample) {
......
// Resume the dispatch cycle with a freshly appended motion sample.
// First we check that the last dispatch entry in the outbound queue is for the same
// motion event to which we appended the motion sample. If we find such a dispatch
// entry, and if it is currently in progress then we try to stream the new sample.
bool wasEmpty = connection->outboundQueue.isEmpty();
if (! wasEmpty && resumeWithAppendedMotionSample) {
......
return;
}
// This is a new event.
// Enqueue a new dispatch entry onto the outbound queue for this connection.
DispatchEntry* dispatchEntry = mAllocator.obtainDispatchEntry(eventEntry, // increments ref
inputTarget->flags, inputTarget->xOffset, inputTarget->yOffset);
......
// Enqueue the dispatch entry.
connection->outboundQueue.enqueueAtTail(dispatchEntry);
// If the outbound queue was previously empty, start the dispatch cycle going.
if (wasEmpty) {
......
startDispatchCycleLocked(currentTime, connection);
}
}
view plaincopy to clipboardprint? void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime, const sp<Connection>& connection) { ...... DispatchEntry* dispatchEntry = connection->outboundQueue.headSentinel.next; // Mark the dispatch entry as in progress. dispatchEntry->inProgress = true; // Update the connection's input state. EventEntry* eventEntry = dispatchEntry->eventEntry; ...... // Publish the event. status_t status; switch (eventEntry->type) { case EventEntry::TYPE_KEY: { KeyEntry* keyEntry = static_cast<KeyEntry*>(eventEntry); // Apply target flags. int32_t action = keyEntry->action; int32_t flags = keyEntry->flags; // Publish the key event. status = connection->inputPublisher.publishKeyEvent(keyEntry->deviceId, keyEntry->source, action, flags, keyEntry->keyCode, keyEntry->scanCode, keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime, keyEntry->eventTime); ...... break; } ...... } // Send the dispatch signal. status = connection->inputPublisher.sendDispatchSignal(); ...... } void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime, const sp<Connection>& connection) { ...... DispatchEntry* dispatchEntry = connection->outboundQueue.headSentinel.next; // Mark the dispatch entry as in progress. dispatchEntry->inProgress = true; // Update the connection's input state. EventEntry* eventEntry = dispatchEntry->eventEntry; ...... // Publish the event. status_t status; switch (eventEntry->type) { case EventEntry::TYPE_KEY: { KeyEntry* keyEntry = static_cast<KeyEntry*>(eventEntry); // Apply target flags. int32_t action = keyEntry->action; int32_t flags = keyEntry->flags; // Publish the key event. status = connection->inputPublisher.publishKeyEvent(keyEntry->deviceId, keyEntry->source, action, flags, keyEntry->keyCode, keyEntry->scanCode, keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime, keyEntry->eventTime); ...... break; } ...... } // Send the dispatch signal. status = connection->inputPublisher.sendDispatchSignal(); ...... }这个函数主要围绕传进来的Connection对象做两件事情，一是从它的outboundQueue队列中取出当前需要处理的键盘事件，然后把这个事件记录在它的内部对象inputPublisher中，二是通过它的内部对象inputPublisher通知它所关联的Activity窗口，现在有键盘事件需要处理了。第一件事情是通过调用它的InputPublisher对象的publishKeyEvent函数来完成的，而第二件事情是通过调用它的InputPublisher对象的sendDispatchSignal来完成的。我们先来看InputPublisher的成员函数publishKeyEvent的实现，然后再回来分析它的另外一个成员函数sendDispatchSignal的实现。
Step 18. InputPublisher.publishKeyEvent
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputPublisher::publishKeyEvent(
int32_t deviceId,
int32_t source,
int32_t action,
int32_t flags,
int32_t keyCode,
int32_t scanCode,
int32_t metaState,
int32_t repeatCount,
nsecs_t downTime,
nsecs_t eventTime) {
......
status_t result = publishInputEvent(AINPUT_EVENT_TYPE_KEY, deviceId, source);
if (result < 0) {
return result;
}
mSharedMessage->key.action = action;
mSharedMessage->key.flags = flags;
mSharedMessage->key.keyCode = keyCode;
mSharedMessage->key.scanCode = scanCode;
mSharedMessage->key.metaState = metaState;
mSharedMessage->key.repeatCount = repeatCount;
mSharedMessage->key.downTime = downTime;
mSharedMessage->key.eventTime = eventTime;
return OK;
}
view plaincopy to clipboardprint? sp<Connection> connection = new Connection(inputChannel); status_t status = connection->initialize(); sp<Connection> connection = new Connection(inputChannel); status_t status = connection->initialize();我们来看一下这个initialize函数的实现，它定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputPublisher::initialize() {
......
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_get_size_region(ashmemFd);
......
mAshmemSize = (size_t) result;
mSharedMessage = static_cast<InputMessage*>(mmap(NULL, mAshmemSize,
PROT_READ | PROT_WRITE, MAP_SHARED, ashmemFd, 0));
......
mPinned = true;
mSharedMessage->consumed = false;
return reset();
}
view plaincopy to clipboardprint? status_t InputPublisher::sendDispatchSignal() { ...... mWasDispatched = true; return mChannel->sendSignal(INPUT_SIGNAL_DISPATCH); } status_t InputPublisher::sendDispatchSignal() { ...... mWasDispatched = true; return mChannel->sendSignal(INPUT_SIGNAL_DISPATCH); }这个函数很简单，它通过调用内部成员变量mChannel的sendSignal函数来通知相应的Activity窗口来处理键盘事件。
Step 20. InputChannel.sendSignal
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputChannel::sendSignal(char signal) {
ssize_t nWrite;
do {
nWrite = ::write(mSendPipeFd, & signal, 1);
} while (nWrite == -1 && errno == EINTR);
if (nWrite == 1) {
......
return OK;
}
return -errno;
}
view plaincopy to clipboardprint? int NativeInputQueue::handleReceiveCallback(int receiveFd, int events, void* data) { NativeInputQueue* q = static_cast<NativeInputQueue*>(data); JNIEnv* env = AndroidRuntime::getJNIEnv(); sp<Connection> connection; InputEvent* inputEvent; jobject inputHandlerObjLocal; jlong finishedToken; { // acquire lock AutoMutex _l(q->mLock); ssize_t connectionIndex = q->mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... connection = q->mConnectionsByReceiveFd.valueAt(connectionIndex); ...... status_t status = connection->inputConsumer.receiveDispatchSignal(); if (status) { ...... return 0; // remove the callback } ...... status = connection->inputConsumer.consume(& connection->inputEventFactory, & inputEvent); ...... finishedToken = generateFinishedToken(receiveFd, connection->id, connection->messageSeqNum); inputHandlerObjLocal = env->NewLocalRef(connection->inputHandlerObjGlobal); } // release lock ...... int32_t inputEventType = inputEvent->getType(); jobject inputEventObj; jmethodID dispatchMethodId; switch (inputEventType) { case AINPUT_EVENT_TYPE_KEY: ...... inputEventObj = android_view_KeyEvent_fromNative(env, static_cast<KeyEvent*>(inputEvent)); dispatchMethodId = gInputQueueClassInfo.dispatchKeyEvent; break; } ...... } ...... env->CallStaticVoidMethod(gInputQueueClassInfo.clazz, dispatchMethodId, inputHandlerObjLocal, inputEventObj, jlong(finishedToken)); ...... return 1; } int NativeInputQueue::handleReceiveCallback(int receiveFd, int events, void* data) { NativeInputQueue* q = static_cast<NativeInputQueue*>(data); JNIEnv* env = AndroidRuntime::getJNIEnv(); sp<Connection> connection; InputEvent* inputEvent; jobject inputHandlerObjLocal; jlong finishedToken; { // acquire lock AutoMutex _l(q->mLock); ssize_t connectionIndex = q->mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... connection = q->mConnectionsByReceiveFd.valueAt(connectionIndex); ...... status_t status = connection->inputConsumer.receiveDispatchSignal(); if (status) { ...... return 0; // remove the callback } ...... status = connection->inputConsumer.consume(& connection->inputEventFactory, & inputEvent); ...... finishedToken = generateFinishedToken(receiveFd, connection->id, connection->messageSeqNum); inputHandlerObjLocal = env->NewLocalRef(connection->inputHandlerObjGlobal); } // release lock ...... int32_t inputEventType = inputEvent->getType(); jobject inputEventObj; jmethodID dispatchMethodId; switch (inputEventType) { case AINPUT_EVENT_TYPE_KEY: ...... inputEventObj = android_view_KeyEvent_fromNative(env, static_cast<KeyEvent*>(inputEvent)); dispatchMethodId = gInputQueueClassInfo.dispatchKeyEvent; break; } ...... } ...... env->CallStaticVoidMethod(gInputQueueClassInfo.clazz, dispatchMethodId, inputHandlerObjLocal, inputEventObj, jlong(finishedToken)); ...... return 1; }
这个函数首先是通过参数data获得当初注册InputChannel的NativeInputQueue对象，具体可以参考前面介绍的应用程序注册键盘消息接收通道过程的Step 21。接下来再通过参数receiveFd获得保存在这个NativeInputQueue对象中的mConnectionsByReceiveFd成员变量中的Connection对象。有了这个Connection对象后，就可以获得它内部的InputConsumer对象，这个InputConsumer对象是和上面的Step 18中介绍的InputPublisher对象相应的。
在InputChannel内部中，分别有一个InputPublisher对象和一个InputConsumer对象，对于Server端的InputChannel来说，它使用的是InputPublisher对象，通过它进行键盘消息的分发，而对于Client端的InputChannel来说，它使用的是InputConsumer对象，通过它进行键盘消息的读取。
获得了这个InputConsumer对象后首先是调用它的receiveDispatchSignal来确认是否是接收到了键盘消息的通知，如果是的话，再调用它的consume函数来把键盘事件读取出来，最后，调用Java层的回调对象InputQueue的DispatchKeyEvent来处理这个键盘事件。下面，我们就依次来分析这些过程。
Step 22. InputConsumer.receiveDispatchSignal
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputConsumer::receiveDispatchSignal() {
......
char signal;
status_t result = mChannel->receiveSignal(& signal);
if (result) {
return result;
}
if (signal != INPUT_SIGNAL_DISPATCH) {
......
return UNKNOWN_ERROR;
}
return OK;
}
view plaincopy to clipboardprint? status_t InputChannel::receiveSignal(char* outSignal) { ssize_t nRead; do { nRead = ::read(mReceivePipeFd, outSignal, 1); } while (nRead == -1 && errno == EINTR); if (nRead == 1) { ...... return OK; } ...... return -errno; } status_t InputChannel::receiveSignal(char* outSignal) { ssize_t nRead; do { nRead = ::read(mReceivePipeFd, outSignal, 1); } while (nRead == -1 && errno == EINTR); if (nRead == 1) { ...... return OK; } ...... return -errno; }Step 23. InputConsumer.consume
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputConsumer::consume(InputEventFactoryInterface* factory, InputEvent** outEvent) {
......
*outEvent = NULL;
int ashmemFd = mChannel->getAshmemFd();
int result = ashmem_pin_region(ashmemFd, 0, 0);
......
if (mSharedMessage->consumed) {
......
return INVALID_OPERATION;
}
// Acquire but *never release* the semaphore. Contention on the semaphore is used to signal
// to the publisher that the message has been consumed (or is in the process of being
// consumed). Eventually the publisher will reinitialize the semaphore for the next message.
result = sem_wait(& mSharedMessage->semaphore);
......
mSharedMessage->consumed = true;
switch (mSharedMessage->type) {
case AINPUT_EVENT_TYPE_KEY: {
KeyEvent* keyEvent = factory->createKeyEvent();
if (! keyEvent) return NO_MEMORY;
populateKeyEvent(keyEvent);
*outEvent = keyEvent;
break;
}
......
}
return OK;
}
view plaincopy to clipboardprint? connection->inputHandlerObjGlobal = env->NewGlobalRef(inputHandlerObj); connection->inputHandlerObjGlobal = env->NewGlobalRef(inputHandlerObj);这个inputHandlerObj对象的类型为Java层的InputHandler对象，因此，这里首先把它取回来：
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inputHandlerObjLocal = env->NewLocalRef(connection->inputHandlerObjGlobal);
view plaincopy to clipboardprint? dispatchMethodId = gInputQueueClassInfo.dispatchKeyEvent; dispatchMethodId = gInputQueueClassInfo.dispatchKeyEvent;在回调用这个InputQueue类的dispatchKeyEvent静态成员函数之前，还要把前面获得的inputEvent对象转换成Java层的KeyEvent对象：
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inputEventObj = android_view_KeyEvent_fromNative(env,
static_cast<KeyEvent*>(inputEvent));
view plaincopy to clipboardprint? env->CallStaticVoidMethod(gInputQueueClassInfo.clazz, dispatchMethodId, inputHandlerObjLocal, inputEventObj, jlong(finishedToken)); env->CallStaticVoidMethod(gInputQueueClassInfo.clazz, dispatchMethodId, inputHandlerObjLocal, inputEventObj, jlong(finishedToken));Step 24. InputQueue.dispatchKeyEvent
这个函数定义在frameworks/base/core/java/android/view/InputQueue.java文件中：
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public final class InputQueue {
......
private static void dispatchKeyEvent(InputHandler inputHandler,
KeyEvent event, long finishedToken) {
Runnable finishedCallback = FinishedCallback.obtain(finishedToken);
inputHandler.handleKey(event, finishedCallback);
}
......
}
view plaincopy to clipboardprint? InputQueue.registerInputChannel(mInputChannel, mInputHandler, Looper.myQueue()); InputQueue.registerInputChannel(mInputChannel, mInputHandler, Looper.myQueue());它是ViewRoot类的一个成员变量mInputHandler。因此，这里将调用ViewRoot类的内部对象mInputHandler的成员函数handleKey来处理键盘事件。
Step 25. InputHandler.handleKey
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
private final InputHandler mInputHandler = new InputHandler() {
public void handleKey(KeyEvent event, Runnable finishedCallback) {
startInputEvent(finishedCallback);
dispatchKey(event, true);
}
......
};
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void startInputEvent(Runnable finishedCallback) { ...... mFinishedCallback = finishedCallback; } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void startInputEvent(Runnable finishedCallback) { ...... mFinishedCallback = finishedCallback; } ...... }然后再调用其外部类ViewRoot的dispatchKey成员函数来进一步处这个键盘事件。
Step 26. ViewRoot.dispatchKey
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
private void dispatchKey(KeyEvent event, boolean sendDone) {
......
Message msg = obtainMessage(DISPATCH_KEY);
msg.obj = event;
msg.arg1 = sendDone ? 1 : 0;
......
sendMessageAtTime(msg, event.getEventTime());
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void deliverKeyEvent(KeyEvent event, boolean sendDone) { // If mView is null, we just consume the key event because it doesn't // make sense to do anything else with it. boolean handled = mView != null ? mView.dispatchKeyEventPreIme(event) : true; ...... // If it is possible for this window to interact with the input // method window, then we want to first dispatch our key events // to the input method. if (mLastWasImTarget) { InputMethodManager imm = InputMethodManager.peekInstance(); if (imm != null && mView != null) { ...... imm.dispatchKeyEvent(mView.getContext(), seq, event, mInputMethodCallback); return; } } ...... } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void deliverKeyEvent(KeyEvent event, boolean sendDone) { // If mView is null, we just consume the key event because it doesn't // make sense to do anything else with it. boolean handled = mView != null ? mView.dispatchKeyEventPreIme(event) : true; ...... // If it is possible for this window to interact with the input // method window, then we want to first dispatch our key events // to the input method. if (mLastWasImTarget) { InputMethodManager imm = InputMethodManager.peekInstance(); if (imm != null && mView != null) { ...... imm.dispatchKeyEvent(mView.getContext(), seq, event, mInputMethodCallback); return; } } ...... } ...... }ViewRoot在把这个键盘事件分发给当前激活的Activity窗口处理之前，首先会调用InputMethodManager的dispatchKeyEvent成员函数来处理这个键盘事件。InputMethodManager处理完这个键盘事件后，再回调用这里的mInputMethodCallback对象的finishedEvent成员函数来把键盘事件分发给当前激活的Activity窗口处理。当然，在把这个键盘事件分发给InputMethodManager处理之前，ViewRoot也会先把这个键盘事件分发给当前激活的Activity窗口的dispatchKeyEventPreIme成员函数处理。
Step 28. InputMethodManager.dispatchKeyEvent
这个函数定义在frameworks/base/core/java/android/view/inputmethod/InputMethodManager.java文件中。这是一个输入法相关的类，我们这里就不关注了，只要知道当输入法处理完成之后，它就会调用ViewRoot类的mInputMehtodCallback对象的finishedEvent成员函数。
Step 29. InputMethodCallack.finishedEvent
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
static class InputMethodCallback extends IInputMethodCallback.Stub {
private WeakReference<ViewRoot> mViewRoot;
public InputMethodCallback(ViewRoot viewRoot) {
mViewRoot = new WeakReference<ViewRoot>(viewRoot);
}
public void finishedEvent(int seq, boolean handled) {
final ViewRoot viewRoot = mViewRoot.get();
if (viewRoot != null) {
viewRoot.dispatchFinishedEvent(seq, handled);
}
}
......
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void dispatchFinishedEvent(int seq, boolean handled) { Message msg = obtainMessage(FINISHED_EVENT); msg.arg1 = seq; msg.arg2 = handled ? 1 : 0; sendMessage(msg); } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void dispatchFinishedEvent(int seq, boolean handled) { Message msg = obtainMessage(FINISHED_EVENT); msg.arg1 = seq; msg.arg2 = handled ? 1 : 0; sendMessage(msg); } ...... }和前面的Step 26一样，ViewRoot不是直接处理这个键盘事件，而是把它作为一个消息（FINISHED_EVENT）放在消息队列中去，最后，这个消息由ViewRoot的handleFinishedEvent函数来处理。
Step 31. ViewRoot.handleFinishedEvent
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
void handleFinishedEvent(int seq, boolean handled) {
final KeyEvent event = (KeyEvent)retrievePendingEvent(seq);
......
if (event != null) {
final boolean sendDone = seq >= 0;
if (!handled) {
deliverKeyEventToViewHierarchy(event, sendDone);
return;
} else if (sendDone) {
......
} else {
......
}
}
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void deliverKeyEventToViewHierarchy(KeyEvent event, boolean sendDone) { try { if (mView != null && mAdded) { ...... boolean keyHandled = mView.dispatchKeyEvent(event); } ...... } finally { if (sendDone) { finishInputEvent(); } } } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void deliverKeyEventToViewHierarchy(KeyEvent event, boolean sendDone) { try { if (mView != null && mAdded) { ...... boolean keyHandled = mView.dispatchKeyEvent(event); } ...... } finally { if (sendDone) { finishInputEvent(); } } } ...... }这个函数首先会调用ViewRoot类的成员变量mView的dispatchKeyEvent来处理这个键盘事件，然后最调用ViewRoot类的finishInputEvent来处理手尾工作。
ViewRoot类的成员变量mView的类型为DecorView，它是由ActivityThread类第一次Resume当前的Activity窗口时创建的，具体可以参考ActivityThread类的handleResumeActivity成员函数，这里就不关注了。
Step 33. DecorView.dispatchKeyEvent
这个函数定义在frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindow.java文件中，它是PhoneWindow类的一个内部类：
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public class PhoneWindow extends Window implements MenuBuilder.Callback {
......
private final class DecorView extends FrameLayout implements RootViewSurfaceTaker {
......
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
......
final Callback cb = getCallback();
final boolean handled = cb != null && mFeatureId < 0 ? cb.dispatchKeyEvent(event)
: super.dispatchKeyEvent(event);
......
}
......
}
......
}
view plaincopy to clipboardprint? public class Activity extends ContextThemeWrapper implements LayoutInflater.Factory, Window.Callback, KeyEvent.Callback, OnCreateContextMenuListener, ComponentCallbacks { ...... public boolean dispatchKeyEvent(KeyEvent event) { ...... View decor = mDecor; if (decor == null) decor = win.getDecorView(); return event.dispatch(this, decor != null ? decor.getKeyDispatcherState() : null, this); } ...... } public class Activity extends ContextThemeWrapper implements LayoutInflater.Factory, Window.Callback, KeyEvent.Callback, OnCreateContextMenuListener, ComponentCallbacks { ...... public boolean dispatchKeyEvent(KeyEvent event) { ...... View decor = mDecor; if (decor == null) decor = win.getDecorView(); return event.dispatch(this, decor != null ? decor.getKeyDispatcherState() : null, this); } ...... }这里，Activity不是直接处理这个键盘事件，而是通过KeyEvent的dispatch转发一下。注意，KeyEvent的成中函数dispatch的第一个参数的类型是KeyEvent.Callback，而Activity实现了这个接口，因此，这里可以传this引用过去。
Step 35. KeyEvent.dispatch
这个函数定义在frameworks/base/core/java/android/view/KeyEvent.java文件中：
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public class KeyEvent extends InputEvent implements Parcelable {
......
public final boolean dispatch(Callback receiver, DispatcherState state,
Object target) {
switch (mAction) {
case ACTION_DOWN: {
......
boolean res = receiver.onKeyDown(mKeyCode, this);
......
return res;
}
case ACTION_UP:
......
return receiver.onKeyUp(mKeyCode, this);
case ACTION_MULTIPLE:
final int count = mRepeatCount;
final int code = mKeyCode;
if (receiver.onKeyMultiple(code, count, this)) {
return true;
}
......
return false;
}
return false;
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void finishInputEvent() { ...... if (mFinishedCallback != null) { mFinishedCallback.run(); mFinishedCallback = null; } else { ...... } } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... private void finishInputEvent() { ...... if (mFinishedCallback != null) { mFinishedCallback.run(); mFinishedCallback = null; } else { ...... } } ...... }
ViewRoot类里面的成员变量mFinishedCallback是在前面Step 25中由InputQueue设置的，它是一个Runnable对象，实际类型是定义在InputQueue的内部类FinishedCallback，因此，这里调用它的run方法时，接下来就会调用InputQueue的内部类FinishedCallback的run成员函数：
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public final class InputQueue {
......
private static class FinishedCallback implements Runnable {
......
public void run() {
synchronized (sLock) {
......
nativeFinished(mFinishedToken);
......
}
}
......
}
......
}
view plaincopy to clipboardprint? static void android_view_InputQueue_nativeFinished(JNIEnv* env, jclass clazz, jlong finishedToken) { status_t status = gNativeInputQueue.finished( env, finishedToken, false /*ignoreSpuriousFinish*/); ...... } static void android_view_InputQueue_nativeFinished(JNIEnv* env, jclass clazz, jlong finishedToken) { status_t status = gNativeInputQueue.finished( env, finishedToken, false /*ignoreSpuriousFinish*/); ...... }这个函数只是简单只调用NativeInputQueue的finished方法来进一处处理。
Step 38. NativeInputQueue.finished
这个函数定义在frameworks/base/core/jni/android_view_InputQueue.cpp文件中：
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status_t NativeInputQueue::finished(JNIEnv* env, jlong finishedToken, bool ignoreSpuriousFinish) {
int32_t receiveFd;
uint16_t connectionId;
uint16_t messageSeqNum;
parseFinishedToken(finishedToken, &receiveFd, &connectionId, &messageSeqNum);
{ // acquire lock
AutoMutex _l(mLock);
ssize_t connectionIndex = mConnectionsByReceiveFd.indexOfKey(receiveFd);
......
sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);
......
connection->messageInProgress = false;
status_t status = connection->inputConsumer.sendFinishedSignal();
......
} // release lock
return OK;
}
view plaincopy to clipboardprint? finishedToken = generateFinishedToken(receiveFd, connection->id, connection->messageSeqNum); finishedToken = generateFinishedToken(receiveFd, connection->id, connection->messageSeqNum);函数generateFinishedToken的定义如下：
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jlong NativeInputQueue::generateFinishedToken(int32_t receiveFd, uint16_t connectionId,
uint16_t messageSeqNum) {
return (jlong(receiveFd) << 32) | (jlong(connectionId) << 16) | jlong(messageSeqNum);
}
view plaincopy to clipboardprint? parseFinishedToken(finishedToken, &receiveFd, &connectionId, &messageSeqNum); parseFinishedToken(finishedToken, &receiveFd, &connectionId, &messageSeqNum);parseFinishedToken的定义如下：
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void NativeInputQueue::parseFinishedToken(jlong finishedToken,
int32_t* outReceiveFd, uint16_t* outConnectionId, uint16_t* outMessageIndex) {
*outReceiveFd = int32_t(finishedToken >> 32);
*outConnectionId = uint16_t(finishedToken >> 16);
*outMessageIndex = uint16_t(finishedToken);
}
view plaincopy to clipboardprint? ssize_t connectionIndex = mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); ssize_t connectionIndex = mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);接下来就是调用这个connection对象中的inputConsumer对象来发送信号通知Server端的InputChannel，应用程序这一侧处理完刚才发生的键盘事件了：
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status_t status = connection->inputConsumer.sendFinishedSignal();
view plaincopy to clipboardprint? status_t InputConsumer::sendFinishedSignal() { ...... return mChannel->sendSignal(INPUT_SIGNAL_FINISHED); } status_t InputConsumer::sendFinishedSignal() { ...... return mChannel->sendSignal(INPUT_SIGNAL_FINISHED); }这个函数的实现很简单，只是调用其内部对象mChannel的sendSignal函数来执行发送信号的通知。前面我们已经说过，这里的mChannel的类型为InputChannel，它是注册在应用程序一侧的Client端InputChannel，它的成员函数sendSignal的定义我们在上面的Step 20中已经分析过了，这里不再详述，不过，这里和上面Step 20不一样的地方是，它里的通知方向是从反向管道的写端（在应用程序这一侧）到反向管道的读端（在InputDispatcher这一侧）。
前面我们在分析应用程序注册键盘消息接收通道的过程时，在Step 18（InputDispatcher.registerInputChannel）中，说到InputDispatcher把一个反向管道的读端文件描述符添加到WindowManagerService所运行的线程中的Looper对象中去，然后就会在这个反向管道的读端上睡眠等待有这个管道有新的内容可读。现在，InputConsumer往这个反向管道写入新的内容了，于是，InputDispatcher就被唤醒过来了，唤醒过来后，它所调用的函数是InputDispatcher.handleReceiveCallback函数，这与前面的Step
21的逻辑是一样的。
Step 40. InputDispatcher.handleReceiveCallack
这个函数定义在frameworks/base/libs/ui/InputDispatcher.cpp文件中：
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int InputDispatcher::handleReceiveCallback(int receiveFd, int events, void* data) {
InputDispatcher* d = static_cast<InputDispatcher*>(data);
{ // acquire lock
AutoMutex _l(d->mLock);
ssize_t connectionIndex = d->mConnectionsByReceiveFd.indexOfKey(receiveFd);
......
nsecs_t currentTime = now();
sp<Connection> connection = d->mConnectionsByReceiveFd.valueAt(connectionIndex);
......
status_t status = connection->inputPublisher.receiveFinishedSignal();
if (status) {
......
return 0; // remove the callback
}
d->finishDispatchCycleLocked(currentTime, connection);
......
return 1;
} // release lock
}
view plaincopy to clipboardprint? ssize_t connectionIndex = d->mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... sp<Connection> connection = d->mConnectionsByReceiveFd.valueAt(connectionIndex); ssize_t connectionIndex = d->mConnectionsByReceiveFd.indexOfKey(receiveFd); ...... sp<Connection> connection = d->mConnectionsByReceiveFd.valueAt(connectionIndex);然后通过调用这个connection对象的内部对象inputPublisher的receiveFinishedSignal函数来确认是否真的收到键盘事件处理完成的信号，确认之后，就会调用InputDispatcher对象d的finishDispatchCycleLocked函数来执行一些善后工作。下面我们就依次分析这两个过程。
Step 41. InputPublisher.receiverFinishedSignal
这个函数定义在frameworks/base/libs/ui/InputTransport.cpp文件中：
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status_t InputPublisher::receiveFinishedSignal() {
....
char signal;
status_t result = mChannel->receiveSignal(& signal);
if (result) {
return result;
}
if (signal != INPUT_SIGNAL_FINISHED) {
.......
return UNKNOWN_ERROR;
}
return OK;
}
view plaincopy to clipboardprint? void InputDispatcher::finishDispatchCycleLocked(nsecs_t currentTime, const sp<Connection>& connection) { ...... // Notify other system components. onDispatchCycleFinishedLocked(currentTime, connection); // Reset the publisher since the event has been consumed. // We do this now so that the publisher can release some of its internal resources // while waiting for the next dispatch cycle to begin. status_t status = connection->inputPublisher.reset(); ...... startNextDispatchCycleLocked(currentTime, connection); } void InputDispatcher::finishDispatchCycleLocked(nsecs_t currentTime, const sp<Connection>& connection) { ...... // Notify other system components. onDispatchCycleFinishedLocked(currentTime, connection); // Reset the publisher since the event has been consumed. // We do this now so that the publisher can release some of its internal resources // while waiting for the next dispatch cycle to begin. status_t status = connection->inputPublisher.reset(); ...... startNextDispatchCycleLocked(currentTime, connection); }这个函数主要就是做了三件事情：
一是通知其它系统，InputDispatcher完成了一次键盘事件的处理：
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// Notify other system components.
onDispatchCycleFinishedLocked(currentTime, connection);
view plaincopy to clipboardprint? // Reset the publisher since the event has been consumed. // We do this now so that the publisher can release some of its internal resources // while waiting for the next dispatch cycle to begin. status_t status = connection->inputPublisher.reset(); // Reset the publisher since the event has been consumed. // We do this now so that the publisher can release some of its internal resources // while waiting for the next dispatch cycle to begin. status_t status = connection->inputPublisher.reset();三是调用InputDispatcher的startNextDispatchCycleLocked函数来处理下一个键盘事件：
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startNextDispatchCycleLocked(currentTime, connection);
view plaincopy to clipboardprint? class ActivityRecord extends IApplicationToken.Stub { ...... boolean nowVisible; // is this activity's window visible? boolean idle; // has the activity gone idle? ...... public void windowsVisible() { synchronized(service) { ...... if (!nowVisible) { nowVisible = true; if (!idle) { ....... } else { // If this activity was already idle, then we now need to // make sure we perform the full stop of any activities // that are waiting to do so. This is because we won't // do that while they are still waiting for this one to // become visible. final int N = stack.mWaitingVisibleActivities.size(); if (N > 0) { for (int i=0; i<N; i++) { ActivityRecord r = (ActivityRecord) stack.mWaitingVisibleActivities.get(i); r.waitingVisible = false; ...... } stack.mWaitingVisibleActivities.clear(); Message msg = Message.obtain(); msg.what = ActivityStack.IDLE_NOW_MSG; stack.mHandler.sendMessage(msg); } } ...... } } } ...... } class ActivityRecord extends IApplicationToken.Stub { ...... boolean nowVisible; // is this activity's window visible? boolean idle; // has the activity gone idle? ...... public void windowsVisible() { synchronized(service) { ...... if (!nowVisible) { nowVisible = true; if (!idle) { ....... } else { // If this activity was already idle, then we now need to // make sure we perform the full stop of any activities // that are waiting to do so. This is because we won't // do that while they are still waiting for this one to // become visible. final int N = stack.mWaitingVisibleActivities.size(); if (N > 0) { for (int i=0; i<N; i++) { ActivityRecord r = (ActivityRecord) stack.mWaitingVisibleActivities.get(i); r.waitingVisible = false; ...... } stack.mWaitingVisibleActivities.clear(); Message msg = Message.obtain(); msg.what = ActivityStack.IDLE_NOW_MSG; stack.mHandler.sendMessage(msg); } } ...... } } } ...... }应用程序中的每一个Activity在ActivityManagerService都有一个代表ActivityRecord，它们以堆栈的形式组织在ActivityManaerService中的ActivityStack中。一个即将要显示，但是还没有显示的Activity，它在ActivityManagerService中的ActivityRecord的成员变量nowVisible为false，而成员变量idle为ture，表示这个即将要显示的Activity窗口处于空闲状态。因此，在上面的这个函数中，会执行下面的语句：
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final int N = stack.mWaitingVisibleActivities.size();
if (N > 0) {
for (int i=0; i<N; i++) {
ActivityRecord r = (ActivityRecord)
stack.mWaitingVisibleActivities.get(i);
r.waitingVisible = false;
......
}
stack.mWaitingVisibleActivities.clear();
Message msg = Message.obtain();
msg.what = ActivityStack.IDLE_NOW_MSG;
stack.mHandler.sendMessage(msg);
}
view plaincopy to clipboardprint? public class ActivityStack { ...... final void activityIdleInternal(IBinder token, boolean fromTimeout, Configuration config) { ...... ArrayList<ActivityRecord> stops = null; ...... int NS = 0; ...... synchronized (mService) { ...... // Atomically retrieve all of the other things to do. stops = processStoppingActivitiesLocked(true); NS = stops != null ? stops.size() : 0; ...... } int i; ...... // Stop any activities that are scheduled to do so but have been // waiting for the next one to start. for (i=0; i<NS; i++) { ActivityRecord r = (ActivityRecord)stops.get(i); synchronized (mService) { if (r.finishing) { finishCurrentActivityLocked(r, FINISH_IMMEDIATELY); } else { ...... } } } ...... } ...... } public class ActivityStack { ...... final void activityIdleInternal(IBinder token, boolean fromTimeout, Configuration config) { ...... ArrayList<ActivityRecord> stops = null; ...... int NS = 0; ...... synchronized (mService) { ...... // Atomically retrieve all of the other things to do. stops = processStoppingActivitiesLocked(true); NS = stops != null ? stops.size() : 0; ...... } int i; ...... // Stop any activities that are scheduled to do so but have been // waiting for the next one to start. for (i=0; i<NS; i++) { ActivityRecord r = (ActivityRecord)stops.get(i); synchronized (mService) { if (r.finishing) { finishCurrentActivityLocked(r, FINISH_IMMEDIATELY); } else { ...... } } } ...... } ...... }这个函数首先会调用processStoppingActivitiesLocked函数把所有处于Stopped状态的Activity取回来，然后逐个分析它们，如果它们的ActivityRecord中的finishing成员变量为true，就说明这个Activity需要销毁了，于是，就调用finishCurrentActivityLocked函数来销毁它们。
Step 3. ActivityStack.finishCurrentActivityLocked
这个函数定义在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件中：
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public class ActivityStack {
......
private final ActivityRecord finishCurrentActivityLocked(ActivityRecord r,
int mode) {
......
return finishCurrentActivityLocked(r, index, mode);
}
private final ActivityRecord finishCurrentActivityLocked(ActivityRecord r,
int index, int mode) {
......
// make sure the record is cleaned out of other places.
mStoppingActivities.remove(r);
mWaitingVisibleActivities.remove(r);
......
final ActivityState prevState = r.state;
r.state = ActivityState.FINISHING;
if (mode == FINISH_IMMEDIATELY
|| prevState == ActivityState.STOPPED
|| prevState == ActivityState.INITIALIZING) {
// If this activity is already stopped, we can just finish
// it right now.
return destroyActivityLocked(r, true) ? null : r;
} else {
......
}
return r;
}
......
}
view plaincopy to clipboardprint? public class ActivityStack { ...... final boolean destroyActivityLocked(ActivityRecord r, boolean removeFromApp) { ...... boolean removedFromHistory = false; ...... final boolean hadApp = r.app != null; if (hadApp) { ...... try { ...... r.app.thread.scheduleDestroyActivity(r, r.finishing, r.configChangeFlags); } catch (Exception e) { ...... } ...... } else { ...... } ...... return removedFromHistory; } ...... } public class ActivityStack { ...... final boolean destroyActivityLocked(ActivityRecord r, boolean removeFromApp) { ...... boolean removedFromHistory = false; ...... final boolean hadApp = r.app != null; if (hadApp) { ...... try { ...... r.app.thread.scheduleDestroyActivity(r, r.finishing, r.configChangeFlags); } catch (Exception e) { ...... } ...... } else { ...... } ...... return removedFromHistory; } ...... }在前面一篇文章Android应用程序启动过程源代码分析中，我们说到，每一个应用程序进程在ActivityManagerService中，都ProcessRecord记录与之对应，而每一个Activity，都是运行在一个进程上下文中，因此，在ActivityManagerService中，每一个ActivityRecord的app成员变量都应该指向一个ProcessRecord记录，于是，这里得到的hadApp为true。在ProcessRecord类中，有一个成员变量thread，它的类型为IApplicationThread。在文章Android应用程序启动过程源代码分析中，我们也曾经说过，每一个应用程序在启动的时候，它都会在内部创建一个ActivityThread对象，而在这个ActivityThread对象中，有一个成员变量mAppThread，它的类型为ApplicationThread，这是一个Binder对象，专门用来负责在应用程序和ActivityManagerService之间执行进程间通信工作的。应用程序在启动的时候，就会将这个Binder对象传递给ActivityManagerService，而ActivityManagerService就会把它保存在相应的ProcessRecord记录的thread成员变量中。因此，ProcessRecord记录的thread成员变量其实就是ApplicationThread对象的远程接口，于是，执行下面这个语句的时候：
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r.app.thread.scheduleDestroyActivity(r, r.finishing,
r.configChangeFlags);
view plaincopy to clipboardprint? public final class ActivityThread { ...... private final class ApplicationThread extends ApplicationThreadNative { ...... public final void scheduleDestroyActivity(IBinder token, boolean finishing, int configChanges) { queueOrSendMessage(H.DESTROY_ACTIVITY, token, finishing ? 1 : 0, configChanges); } ...... } ...... } public final class ActivityThread { ...... private final class ApplicationThread extends ApplicationThreadNative { ...... public final void scheduleDestroyActivity(IBinder token, boolean finishing, int configChanges) { queueOrSendMessage(H.DESTROY_ACTIVITY, token, finishing ? 1 : 0, configChanges); } ...... } ...... }这个函数调用外部类ActivityThread的queueOrSendMessage函数来往应用程序的消息队列中发送一个H.DESTROY_ACTIVITY消息，这个消息最终由ActivityThread类的handleDestroyActivity函数来处理。
Step 6. ActivityThread.handleDestroyActivity
这个函数定义在frameworks/base/core/java/android/app/ActivityThread.java文件中：
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public final class ActivityThread {
......
private final void handleDestroyActivity(IBinder token, boolean finishing,
int configChanges, boolean getNonConfigInstance) {
......
ActivityClientRecord r = performDestroyActivity(token, finishing,
configChanges, getNonConfigInstance);
if (r != null) {
WindowManager wm = r.activity.getWindowManager();
View v = r.activity.mDecor;
if (v != null) {
......
if (r.activity.mWindowAdded) {
wm.removeViewImmediate(v);
}
......
}
......
}
......
}
......
}
view plaincopy to clipboardprint? public abstract class Window { ...... private class LocalWindowManager implements WindowManager { ...... public final void removeViewImmediate(View view) { mWindowManager.removeViewImmediate(view); } ...... private final WindowManager mWindowManager; } ...... } public abstract class Window { ...... private class LocalWindowManager implements WindowManager { ...... public final void removeViewImmediate(View view) { mWindowManager.removeViewImmediate(view); } ...... private final WindowManager mWindowManager; } ...... }LocalWindowManager类的成员变量mWindowManager是一个WndowManagerImpl对象，这个函数只是简单地调用WndowManagerImpl类的removeViewImmediate来进一步处理。
Step 8. WndowManagerImpl.removeViewImmediate
这个函数定义在frameworks/base/core/java/android/view/WindowManagerImpl.java文件中：
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public class WindowManagerImpl implements WindowManager {
......
public void removeViewImmediate(View view) {
synchronized (this) {
int index = findViewLocked(view, true);
ViewRoot root = mRoots[index];
......
root.die(true);
......
}
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void die(boolean immediate) { if (immediate) { doDie(); } else { ...... } } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... public void die(boolean immediate) { if (immediate) { doDie(); } else { ...... } } ...... }上面Step 8传进来的immediate参数为true，因此，这里直接调用doDie函数来进一步处理。
Step 10. ViewRoot.doDie
这个函数定义在frameworks/base/core/java/android/view/ViewRoot.java文件中：
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public final class ViewRoot extends Handler implements ViewParent,
View.AttachInfo.Callbacks {
......
void doDie() {
......
synchronized (this) {
......
if (mAdded) {
mAdded = false;
dispatchDetachedFromWindow();
}
}
}
......
}
view plaincopy to clipboardprint? public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... void dispatchDetachedFromWindow() { ...... if (mInputChannel != null) { if (mInputQueueCallback != null) { ...... } else { InputQueue.unregisterInputChannel(mInputChannel); } } try { sWindowSession.remove(mWindow); } catch (RemoteException e) { } ...... } ...... } public final class ViewRoot extends Handler implements ViewParent, View.AttachInfo.Callbacks { ...... void dispatchDetachedFromWindow() { ...... if (mInputChannel != null) { if (mInputQueueCallback != null) { ...... } else { InputQueue.unregisterInputChannel(mInputChannel); } } try { sWindowSession.remove(mWindow); } catch (RemoteException e) { } ...... } ...... }前面在介绍应用程序注册键盘消息接收通道的过程时，在Step 18，我们说到，ViewRoot类中的mInputQueueCallback为null，表示由这个ViewRoot自己来管理键盘输入事件，因此，这里首先会调用InputQueue的unregisterInputChannel函数来注销注册在应用程序这一侧的Client端InputChannel，然后再调用sWindowSession的remove函数来注销注册在InputManager这一侧的Server端InputChannel，这个逻辑是和前面介绍应用程序注册键盘消息接收通道的逻辑相对应的，前面分别注册了这两个InputChannel，现在Activity要销毁了，当然就要把它们注销了。
我们先来看注销注册在应用程序这一侧的Client端InputChannel，然后再回过头来分析注销注册在InputManager这一侧的Server端InputChannel。
Step 12. InputQueue.unregisterInputChannel
这个函数定义在frameworks/base/core/java/android/view/InputQueue.java文件中：
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public final class InputQueue {
......
public static void unregisterInputChannel(InputChannel inputChannel) {
......
synchronized (sLock) {
......
nativeUnregisterInputChannel(inputChannel);
}
}
......
}
view plaincopy to clipboardprint? static void android_view_InputQueue_nativeUnregisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj) { status_t status = gNativeInputQueue.unregisterInputChannel(env, inputChannelObj); ...... } static void android_view_InputQueue_nativeUnregisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj) { status_t status = gNativeInputQueue.unregisterInputChannel(env, inputChannelObj); ...... }这里调用NativeInputQueue的成员函数unregisterInputChannel来进一步处理。
Step 14. NativeInputQueue.unregisterInputChannel
这个函数定义在frameworks/base/core/jni/android_view_InputQueue.cpp文件中：
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status_t NativeInputQueue::unregisterInputChannel(JNIEnv* env, jobject inputChannelObj) {
sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env,
inputChannelObj);
......
{ // acquire lock
AutoMutex _l(mLock);
ssize_t connectionIndex = getConnectionIndex(inputChannel);
......
sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);
mConnectionsByReceiveFd.removeItemsAt(connectionIndex);
connection->status = Connection::STATUS_ZOMBIE;
connection->looper->removeFd(inputChannel->getReceivePipeFd());
env->DeleteGlobalRef(connection->inputHandlerObjGlobal);
connection->inputHandlerObjGlobal = NULL;
......
} // release lock
......
return OK;
}
view plaincopy to clipboardprint? ssize_t connectionIndex = getConnectionIndex(inputChannel); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); mConnectionsByReceiveFd.removeItemsAt(connectionIndex); ssize_t connectionIndex = getConnectionIndex(inputChannel); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); mConnectionsByReceiveFd.removeItemsAt(connectionIndex);然后再把这个Client端InputChannel的前向管道的读端文件描述符从应用程序主线程中的Looper对象中删除：
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connection->looper->removeFd(inputChannel->getReceivePipeFd());
view plaincopy to clipboardprint? env->DeleteGlobalRef(connection->inputHandlerObjGlobal); connection->inputHandlerObjGlobal = NULL; env->DeleteGlobalRef(connection->inputHandlerObjGlobal); connection->inputHandlerObjGlobal = NULL;回忆一下前面我们在分析InputManager分发键盘消息给应用程序处理时，曾经说到，每当有键盘事件发生时，InputManager首先就会调用NativeInputQueue类的handleReceiveCallback函数。在这个handleReceiveCallback函数里面，NativeInputQueue会找到相应的Connection对象，然后把它里面的内部对象inputHandlerOjbGlobal作为参数来调用Java层的InputQueue类的dispatchKeyEvent函数来通知应用程序，有键盘事件发生了。在InputQueue类的dispatchKeyEvent函数里面，就是通过这个inputHandlerOjbGlobal对象来直正通知到当前激活的Activity窗口来处理这个键盘事件的。
注册在应用程序这一侧的Client端InputChannel被注销以后，回到前面的Step 11中，我们继续分析注销注册在InputManager这一侧的Server端InputChannel。
Step 15. WindowManagerService.Session.remove
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
private final class Session extends IWindowSession.Stub
implements IBinder.DeathRecipient {
......
public void remove(IWindow window) {
removeWindow(this, window);
}
......
}
......
}
view plaincopy to clipboardprint? public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public void removeWindow(Session session, IWindow client) { synchronized(mWindowMap) { WindowState win = windowForClientLocked(session, client, false); if (win == null) { return; } removeWindowLocked(session, win); } } ...... } public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... public void removeWindow(Session session, IWindow client) { synchronized(mWindowMap) { WindowState win = windowForClientLocked(session, client, false); if (win == null) { return; } removeWindowLocked(session, win); } } ...... }
回忆一下前面我们在分析应用程序注册键盘消息管道的过程时，在Step 11（WindowManagerService.addWindow）中，WindowManagerService为这个即将要激活的Activity窗口创建了一个WindowState对象win，创建的时候，使用了从ViewRoot中传过来的两个参数，分别是一个Session对象session和一个IWindow对象client。
在这个函数中，ViewRoot传过来的两个参数session和client和上面说的两个参数是一致的，因此，这个函数首先通过参数session和client得到一个WindowState对象win，然后调用removeWindowLocked来把它从WindowManagerService删除。
Step 17. WindowManagerService.removeWindowLocked
这个函数定义在frameworks/base/services/java/com/android/server/WindowManagerService.java文件中：
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public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
public void removeWindowLocked(Session session, WindowState win) {
......
win.disposeInputChannel();
......
}
......
}
view plaincopy to clipboardprint? public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... private final class WindowState implements WindowManagerPolicy.WindowState { ...... void disposeInputChannel() { if (mInputChannel != null) { mInputManager.unregisterInputChannel(mInputChannel); mInputChannel.dispose(); mInputChannel = null; } } ...... } ...... } public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor { ...... private final class WindowState implements WindowManagerPolicy.WindowState { ...... void disposeInputChannel() { if (mInputChannel != null) { mInputManager.unregisterInputChannel(mInputChannel); mInputChannel.dispose(); mInputChannel = null; } } ...... } ...... }上面说到，在前面分析应用程序注册键盘消息管道的过程时，在Step 11（WindowManagerService.addWindow）中，为当前这个Activity窗口创建了一个WindowState对象，接着创建了一个输入管道后，把Server端的InputChannel保存了在这个WindowState对象的成员变量mInputChannel中，因此，这里，就可以把它取回来，然后调用mInputManager对象的unregisterInputChannel函数来把它注销掉了。
Step 19. InputManager.unregisterInputChannel
这个函数定义在frameworks/base/services/java/com/android/server/InputManager.java文件中：
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public class InputManager {
......
public void unregisterInputChannel(InputChannel inputChannel) {
......
nativeUnregisterInputChannel(inputChannel);
}
......
}
view plaincopy to clipboardprint? static void android_server_InputManager_nativeUnregisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj) { ...... sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env, inputChannelObj); ...... status_t status = gNativeInputManager->unregisterInputChannel(env, inputChannel); ...... } static void android_server_InputManager_nativeUnregisterInputChannel(JNIEnv* env, jclass clazz, jobject inputChannelObj) { ...... sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env, inputChannelObj); ...... status_t status = gNativeInputManager->unregisterInputChannel(env, inputChannel); ...... }这个函数首先调用android_view_InputChannel_getInputChannel函数根据Java层的InputChannel对象找到C++层的InputChannel对象，然后调用NativeInputManager的unregisterInputChannel函数来执行注销的操作。
Step 21. NativeInputManager.unregisterInputChannel
这个函数定义在frameworks/base/services/jni/com_android_server_InputManager.cpp文件中：
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status_t NativeInputManager::unregisterInputChannel(JNIEnv* env,
const sp<InputChannel>& inputChannel) {
......
return mInputManager->getDispatcher()->unregisterInputChannel(inputChannel);
}
view plaincopy to clipboardprint? status_t InputDispatcher::unregisterInputChannel(const sp<InputChannel>& inputChannel) { ...... { // acquire lock AutoMutex _l(mLock); ssize_t connectionIndex = getConnectionIndexLocked(inputChannel); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); mConnectionsByReceiveFd.removeItemsAt(connectionIndex); ...... mLooper->removeFd(inputChannel->getReceivePipeFd()); ..... } // release lock ...... return OK; } status_t InputDispatcher::unregisterInputChannel(const sp<InputChannel>& inputChannel) { ...... { // acquire lock AutoMutex _l(mLock); ssize_t connectionIndex = getConnectionIndexLocked(inputChannel); ...... sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex); mConnectionsByReceiveFd.removeItemsAt(connectionIndex); ...... mLooper->removeFd(inputChannel->getReceivePipeFd()); ..... } // release lock ...... return OK; }这一步与前面的Step 14注销应用程序一侧的Client端InputChannel是差不多的，只不过这里是从InputDispatcher中把Server端的InputChannel注销掉。首先是根据传进来的参数inputChannel找到它在InputDispatcher中对应的Connection对象在mConnectionsByReceiveFd中的索引，然后把它从mConnectionsByReceiveFd中删除：
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to clipboardprint?
ssize_t connectionIndex = getConnectionIndexLocked(inputChannel);
......
sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);
mConnectionsByReceiveFd.removeItemsAt(connectionIndex);
ssize_t connectionIndex = getConnectionIndexLocked(inputChannel);
......
sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);
mConnectionsByReceiveFd.removeItemsAt(connectionIndex); 最后，还需要把这个InputChannel中的反向管道读端文件描述符从InputDispatcher的内部对象mLooper中删除，因为这个文件描述符是在前面注册Server端的InputChannel时加入到mLooper对象去的，具体可以参考上面分析应用程序注册键盘消息接收通道的过程中的Step 18（InputDispatcher.registerInputChannel）。
这样， 应用程序注销键盘消息接收通道的过程就分析完成了，整个应用程序键盘消息处理机制也分析完成了，这是一个比较复杂的过程，要完全理解它还需要花费一些努力和时间，不过，理解了这个过程之后，对Android应用程序框架层的理解就更进一步了。
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