Android 7.1 ActivityManagerService 屏幕旋转流程分析 (四)

四、Activity的更新（旋转）

sendNewConfiguration（）会调用到ActivityManagerService的updateConfiguration（）来update Configuration，并根据应用的配置来判断是否要重新lunch应用。

void sendNewConfiguration() {
try {
mActivityManager.updateConfiguration(null);
} catch (RemoteException e) {
}
}

public void updateConfiguration(Configuration values) {
enforceCallingPermission(android.Manifest.permission.CHANGE_CONFIGURATION,
"updateConfiguration()");

synchronized(this) {
if (values == null && mWindowManager != null) {
// sentinel: fetch the current configuration from the window manager
values = mWindowManager.computeNewConfiguration();
}

if (mWindowManager != null) {
mProcessList.applyDisplaySize(mWindowManager);
}

final long origId = Binder.clearCallingIdentity();
if (values != null) {
Settings.System.clearConfiguration(values);
}
updateConfigurationLocked(values, null, false);
Binder.restoreCallingIdentity(origId);
}
}

先看一下总体时序图，后面详细展开：

1）updateConfigurationLocked（）

updateConfigurationLocked（）
（1）获取Configuration数据保存在mConfiguration
（2）调用ActivityThread的scheduleConfigurationChanged（）
（3）发送ACTION_CONFIGURATION_CHANGED广播
（4）获取当前最上面活动的Activity，调用ActivityStack的ensureActivityConfigurationLocked（）函数根据应用配置判断是否要重新luncher应用

private boolean updateConfigurationLocked(Configuration values, ActivityRecord starting,
boolean initLocale, boolean persistent, int userId, boolean deferResume) {
int changes = 0;

if (mWindowManager != null) {
mWindowManager.deferSurfaceLayout();
}
if (values != null) {
Configuration newConfig = new Configuration(mConfiguration);
changes = newConfig.updateFrom(values);
if (changes != 0) {
if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.i(TAG_CONFIGURATION,
"Updating configuration to: " + values);

EventLog.writeEvent(EventLogTags.CONFIGURATION_CHANGED, changes);

if (!initLocale && !values.getLocales().isEmpty() && values.userSetLocale) {
final LocaleList locales = values.getLocales();
int bestLocaleIndex = 0;
if (locales.size() > 1) {
if (mSupportedSystemLocales == null) {
mSupportedSystemLocales =
Resources.getSystem().getAssets().getLocales();
}
bestLocaleIndex = Math.max(0,
locales.getFirstMatchIndex(mSupportedSystemLocales));
}
SystemProperties.set("persist.sys.locale",
locales.get(bestLocaleIndex).toLanguageTag());
LocaleList.setDefault(locales, bestLocaleIndex);
mHandler.sendMessage(mHandler.obtainMessage(SEND_LOCALE_TO_MOUNT_DAEMON_MSG,
locales.get(bestLocaleIndex)));
}

mConfigurationSeq++;
if (mConfigurationSeq <= 0) {
mConfigurationSeq = 1;
}
newConfig.seq = mConfigurationSeq;
mConfiguration = newConfig;
Slog.i(TAG, "Config changes=" + Integer.toHexString(changes) + " " + newConfig);
mUsageStatsService.reportConfigurationChange(newConfig,
mUserController.getCurrentUserIdLocked());
//mUsageStatsService.noteStartConfig(newConfig);

final Configuration configCopy = new Configuration(mConfiguration);

// TODO: If our config changes, should we auto dismiss any currently
// showing dialogs?
mShowDialogs = shouldShowDialogs(newConfig, mInVrMode);

AttributeCache ac = AttributeCache.instance();
if (ac != null) {
ac.updateConfiguration(configCopy);
}

// Make sure all resources in our process are updated
// right now, so that anyone who is going to retrieve
// resource values after we return will be sure to get
// the new ones.  This is especially important during
// boot, where the first config change needs to guarantee
// all resources have that config before following boot
// code is executed.
mSystemThread.applyConfigurationToResources(configCopy);

if (persistent && Settings.System.hasInterestingConfigurationChanges(changes)) {
Message msg = mHandler.obtainMessage(UPDATE_CONFIGURATION_MSG);
msg.obj = new Configuration(configCopy);
msg.arg1 = userId;
mHandler.sendMessage(msg);
}

final boolean isDensityChange = (changes & ActivityInfo.CONFIG_DENSITY) != 0;
if (isDensityChange) {
// Reset the unsupported display size dialog.
mUiHandler.sendEmptyMessage(SHOW_UNSUPPORTED_DISPLAY_SIZE_DIALOG_MSG);

killAllBackgroundProcessesExcept(Build.VERSION_CODES.N,
ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE);
}

for (int i=mLruProcesses.size()-1; i>=0; i--) {
ProcessRecord app = mLruProcesses.get(i);
try {
if (app.thread != null) {
if (DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION, "Sending to proc "
+ app.processName + " new config " + mConfiguration);
app.thread.scheduleConfigurationChanged(configCopy);
}
} catch (Exception e) {
}
}
Intent intent = new Intent(Intent.ACTION_CONFIGURATION_CHANGED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_REPLACE_PENDING
| Intent.FLAG_RECEIVER_FOREGROUND);
broadcastIntentLocked(null, null, intent, null, null, 0, null, null,
null, AppOpsManager.OP_NONE, null, false, false,
MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
if ((changes&ActivityInfo.CONFIG_LOCALE) != 0) {
intent = new Intent(Intent.ACTION_LOCALE_CHANGED);
intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
if (initLocale || !mProcessesReady) {
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
}
broadcastIntentLocked(null, null, intent,
null, null, 0, null, null, null, AppOpsManager.OP_NONE,
null, false, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
}
}
// Update the configuration with WM first and check if any of the stacks need to be
// resized due to the configuration change. If so, resize the stacks now and do any
// relaunches if necessary. This way we don't need to relaunch again below in
// ensureActivityConfigurationLocked().
if (mWindowManager != null) {
final int[] resizedStacks = mWindowManager.setNewConfiguration(mConfiguration);
if (resizedStacks != null) {
for (int stackId : resizedStacks) {
final Rect newBounds = mWindowManager.getBoundsForNewConfiguration(stackId);
mStackSupervisor.resizeStackLocked(
stackId, newBounds, null, null, false, false, deferResume);
}
}
}
}

boolean kept = true;
final ActivityStack mainStack = mStackSupervisor.getFocusedStack();
// mainStack is null during startup.
if (mainStack != null) {
if (changes != 0 && starting == null) {
// If the configuration changed, and the caller is not already
// in the process of starting an activity, then find the top
// activity to check if its configuration needs to change.
starting = mainStack.topRunningActivityLocked();
}

if (starting != null) {
kept = mainStack.ensureActivityConfigurationLocked(starting, changes, false);
// And we need to make sure at this point that all other activities
// are made visible with the correct configuration.
mStackSupervisor.ensureActivitiesVisibleLocked(starting, changes,
!PRESERVE_WINDOWS);
}
}
if (mWindowManager != null) {
mWindowManager.continueSurfaceLayout();
}
return kept;
}

五、总结

总流程图如下