Power按键流程分析

从InputManagerService分析我们知道，当按下手机的Power键之后，按键事件会传到InputDispatcher 的notifyKey 方法，然后调用到调用了NativeInputManager的interceptKeyBeforeQueueing函数，最终在这个函数中会调用到PhoneWindowManager中的interceptKeyBeforeQueueing函数，以上主要属于InputManagerService的范畴，Power按键流程我们从PhoneWindowManager 的interceptKeyBeforeQueueing 方法开始分析。

方法interceptKeyBeforeQueueing关键步骤：

第一步：初始化关键变量

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if (!mSystemBooted) {

return 0;

}

final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0;

final boolean down = event.getAction() == KeyEvent.ACTION_DOWN;

final boolean canceled = event.isCanceled();

final int keyCode = event.getKeyCode();

final boolean isInjected = (policyFlags & WindowManagerPolicy.FLAG_INJECTED) != 0;

首先判断系统是否启动完成，然后就是初始化一些关键变量

Interactive 表示屏幕是否点亮，这个变量表示PowerManagerService关于屏幕的状态

Down 表示是否是ActionDown事件

Canceled 事件是否取消

keyCode 按键编码

第二步，根据interative的状态的处理一些基本逻辑

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if (interactive || (isInjected && !isWakeKey)) {

//事件传递给用户

result = ACTION_PASS_TO_USER;

isWakeKey = false;

} else if (!interactive && shouldDispatchInputWhenNonInteractive()) {

result = ACTION_PASS_TO_USER;

} else {

result = 0;

if (isWakeKey && (!down || !isWakeKeyWhenScreenOff(keyCode))) {

isWakeKey = false;

}

}

if (isValidGlobalKey(keyCode)

&& mGlobalKeyManager.shouldHandleGlobalKey(keyCode, event)) {

if (isWakeKey) {

//直接唤醒系统

wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, " android.policy:KEY");

}

return result;

}

第三步，处理Power按键的事件

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case KeyEvent.KEYCODE_POWER: {

result &= ~ACTION_PASS_TO_USER;

isWakeKey = false; // wake-up will be handled separately

if (down) {

Power键按下

interceptPowerKeyDown(event, interactive);

} else {

Power键释放

interceptPowerKeyUp(event, interactive, canceled);

}

break;

}

首先是Power按键的事件的话，不再分发到应用，如果是ActionDown事件执行InterceptPowerKeyDown()方法，如果是ActionUP事件则执行InterceptPowerKeyUp()方法

下一步继续分析interceptPowerKeyDown方法

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private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {

if (!mPowerKeyWakeLock.isHeld()) {

mPowerKeyWakeLock.acquire();

}

获取Power按键的锁，直到释放Power键

……

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if (interactive && !mScreenshotChordPowerKeyTriggered

&& (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) {

mScreenshotChordPowerKeyTriggered = true;

mScreenshotChordPowerKeyTime = event.getDownTime();

interceptScreenshotChord();

}

如果当前是亮屏状态，且满足触发截屏的条件，触发截屏功能

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TelecomManager telecomManager = getTelecommService();

boolean hungUp = false;

if (telecomManager != null) {

if (telecomManager.isRinging()) {

telecomManager.silenceRinger();

} else if ((mIncallPowerBehavior

& Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0

&& telecomManager.isInCall() && interactive) {

hungUp = telecomManager.endCall();

}

}

如果有电话拨入，且电话铃声响起的话，这个时候按Power键，设置电话响铃静音

如果正在接听电话，且配置了Power键挂断电话的话，按Power按键挂断正在接听的电话

……

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mPowerKeyHandled = hungUp || mScreenshotChordVolumeDownKeyTriggered

|| mScreenshotChordVolumeUpKeyTriggered || gesturedServiceIntercepted;

如果按Power按键执行了截图功能或者电话静音或者挂断电话等功能后，Power事件不在传递，表示已经消耗掉了Power事件

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if (!mPowerKeyHandled) {

如果未消耗掉Power事件，继续执行此处逻辑

分为两种情况

1， 当前是亮屏状态

2， 当前是灭屏状态

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if (interactive) {

//是否支持长按功能

if (hasLongPressOnPowerBehavior()) {

Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);

msg.setAsynchronous(true);

//发送MSG_POWER_LONG_PRESS消息，有Handler来处理

mHandler.sendMessageDelayed(msg,

ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

}

} else {

//当前灭屏状态，此时按Power键，先唤醒系统

wakeUpFromPowerKey(event.getDownTime());

//是否支持灭屏下的长按功能

if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) {

Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg,

ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

mBeganFromNonInteractive = true;

} else {

final int maxCount = getMaxMultiPressPowerCount();

if (maxCount <= 1) {

mPowerKeyHandled = true;

} else {

mBeganFromNonInteractive = true;

}

}

}

}

}

当前亮屏状态

首先判断是否支持长按的行为

先来看看hasLongPressOnPowerBehavior函数

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private boolean hasLongPressOnPowerBehavior() {

return getResolvedLongPressOnPowerBehavior() != LONG_PRESS_POWER_NOTHING;

}

再来看看getResolvedLongPressOnPowerBehavior函数

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private int getResolvedLongPressOnPowerBehavior() {

if (FactoryTest.isLongPressOnPowerOffEnabled()) {

return LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM;

}

return mLongPressOnPowerBehavior;

}

由于systemProperty中的factory.long_press_power_off" 配置为0，所以不支持灭屏长按功能，。因此只要看mLongPressOnPowerBehavior这个变量

mLongPreesOnPowerBehavior 默认配置获取为

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mLongPressOnPowerBehavior = mContext.getResources().getInteger(

com.android.internal.R.integer.config_longPressOnPowerBehavior);

config_longPressOnPowerBehavior默认值为1，所以mLongPressOnPowerBehavior = 1，最后hasLongPressOnPowerBehavior返回true

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if (hasLongPressOnPowerBehavior()) {

Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg,

ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

}

当hasLongPressOnPowerBehavior返回true，则发送MSG_POWER_LONG_PRESS的Handler消息，Handler处理消息调用 powerLongPress()方法，接着我们来看下Handler处理消息的逻辑

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private void powerLongPress() {

final int behavior = getResolvedLongPressOnPowerBehavior();

switch (behavior) {

case LONG_PRESS_POWER_NOTHING:

break;

case LONG_PRESS_POWER_GLOBAL_ACTIONS:

mPowerKeyHandled = true;

if (!performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false)) {

performAuditoryFeedbackForAccessibilityIfNeed();

}

showGlobalActionsInternal();

break;

……

由以上的分析指导getResolvedLongPressOnPowerBehavior的值为1，所以执行case LONG_PRESS_POWER_GLOBAL_ACTIONS,

将mPowerKeyHandled的值设置为true，表示处理了PowerDown事件，showGlobalActionsInternal()方法弹出关机，重启对话框

1. 当屏幕是灭屏状态

首先执行wakeUpFromPowerKey方法，唤醒手机系统，最终调用mPowerManager.wakeUp(wakeTime, reason)来唤醒手机

然后mSupportLongPressPowerWhenNonInteractive默认不支持，所以默认执行

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final int maxCount = getMaxMultiPressPowerCount();

if (maxCount <= 1) {

mPowerKeyHandled = true;

} else {

mBeganFromNonInteractive = true;

}

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getMaxMultiPressPowerCount() ==1，默认不支持对此按键，所以将mPowerKeyHandled设置为true，表示处理了PowerDown事件

2，处理PowerUp事件

PowerUp事件也分为两种情况，分别对应PowerDown的亮屏和灭屏两种情况

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private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) {

final boolean handled = canceled || mPowerKeyHandled;

……

if (!handled) {

mPowerKeyPressCounter += 1;

final int maxCount = getMaxMultiPressPowerCount();

final long eventTime = event.getDownTime();

if (mPowerKeyPressCounter < maxCount) {

Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS,

interactive ? 1 : 0, mPowerKeyPressCounter, eventTime);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout());

return;

}

powerPress(eventTime, interactive, mPowerKeyPressCounter);

}

finishPowerKeyPress();

}

在灭屏的时候，和亮屏长按的时候mPowerKeyHandled最后设置为true，即handle为true，直接执行finishPowerKeyPress方法，释放mPowerKeyWakeLock

在亮屏短按的时候，handled为false，由以上分析，手机默认不支持多次按键所以maxCount为1，mPowerKeyPressCounter=1，所以直接执行powerPress方法

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private void powerPress(long eventTime, boolean interactive, int count) {

if (count == 2) {

powerMultiPressAction(eventTime, interactive,mDoublePressOnPowerBehavior);

} else if (count == 3) {

powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior);

} else if (interactive && !mBeganFromNonInteractive) {

switch (mShortPressOnPowerBehavior) {

case SHORT_PRESS_POWER_NOTHING:

break;

case SHORT_PRESS_POWER_GO_TO_SLEEP:

mPowerManager.goToSleep(eventTime,

PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0);

break;

case SHORT_PRESS_POWER_REALLY_GO_TO_SLEEP:

mPowerManager.goToSleep(eventTime,

PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON,

PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE);

break;

case SHORT_PRESS_POWER_REALLY_GO_TO_SLEEP_AND_GO_HOME:

mPowerManager.goToSleep(eventTime,

PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON,

PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE);

launchHomeFromHotKey();

break;

case SHORT_PRESS_POWER_GO_HOME:

launchHomeFromHotKey(true /* awakenFromDreams */, false

break;

}

}

}

由于mPowerKeyPressCounter 为1，所以执行case SHORT_PRESS_POWER_GO_TO_SLEEP,调用mPowerManager.goToSleep休眠系统

Power按键流程总结

Power按键

1.亮屏 down

长按 弹出关闭重启对话框

短按 不做处理

亮屏 up

长按 不做处理

短按 调用goToSleep休眠系统

2. 灭屏 down

调用wakeup 唤醒系统

灭屏 up

不做处理

原文地址：　http://blog.csdn.net/zhenjie_chang/article/details/52512823