Android 7.0Power 按键处理流程 _Android

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述Android 7.0Power 按键处理流程相关的知识，希望能为你提供帮助。
android 7.0 Power 按键处理流程

Power按键的处理逻辑由PhoneWindowManager来完成，本文只关注PhoneWindowManager中与Power键相关的内容，其他系统按键的处理类似也是在PhoneWindowManager中处理的。理解了power按键的处理再看其他系统按键的逻辑会容易的多也简单的多。
一、Power按键的上报Power按键的上报流程与其余的按键处理流程一致，在按下power按键后驱动上报按键经InputManagerService处理按键事件，最终将会传递到PhoneWindowManager的interceptKeyBeforeQueueing函数来做具体的业务逻辑。（具体处理 Input system 做详细介绍）本篇侧重power的业务逻辑处理，这里简单介绍下power 按键的上报流程如下图：

文章图片

1-4：在power 按键按下时驱动会上报按键事件，EventHub读取到事件后转给InputReader来做处理。
5-9：InputReader根据上报的事件类型（此处是按键事件），交给KeyBoardInputMapper来做按键映射，根据驱动上报的按键值来映射为android framework的按键值（即KeyEvent.KEYCODE_POWER 和相应的flag），并通知上层。
10-16：经过层调用最后到PhoneWindowManager的interceptKeyBeforeQueueing（）函数来做具体的业务处理。这是本文的重点，下面具体分析。
17-18：通过PowerManagerService来唤醒系统。

二、Power 按键处理PhoneWindowManager的interceptKeyBeforeQueueing（）函数处理具体的业务逻辑，从这个函数开始进行分析。
按键的事件分为按下和抬起两个，framework的处理也是分为按下和抬起来不同的事件分别由不同的函数来处理。

public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) { if (!mSystemBooted) { // If we have not yet booted, don\'t let key events do anything. return 0; } //是否点亮屏幕 final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0; final boolean down = event.getAction() == KeyEvent.ACTION_DOWN; final boolean canceled = event.isCanceled(); //获取按键对应的android framework层的按键编码 final int keyCode = event.getKeyCode(); ................. switch (keyCode) { ........... case KeyEvent.KEYCODE_POWER: { result & = ~ACTION_PASS_TO_USER; isWakeKey = false; // wake-up will be handled separately if (down) { //处理Power键按下 interceptPowerKeyDown(event, interactive); } else { //处理Power键松开 interceptPowerKeyUp(event, interactive, canceled); } break; } } .............. if (isWakeKey) { //按power键时，isWakeKey置为false，于是不会调用wakeUp函数，即不会唤醒系统点亮屏幕 wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY"); } return result; }

扩展：由上可知 isWakeKey 用来控制是否唤醒系统并点亮屏幕，如果需要添加按键需要实现点亮屏幕功能，可以在此处理 ^_^。
接下来，我们分别看一下interceptPowerKeyDown和interceptPowerKeyUp函数。
1、Power按键按下（interceptPowerKeyDown）interceptPowerKeyDown（）用于处理按下Power键(还未抬起)对应的事件。
A: Power按键按下处理时序图

文章图片

处理流程：
1）判断是否power按键与音量按键“同时”按下需要做截屏动作，是则触发截屏。
2）是否为响铃或通话状态，是则执行与之相关配置的动作（默认响铃会静音，如果设置按power挂断电话则挂断）。
3）判断是否为长按，是则根据配置执行长按行为的动作。
B: 代码分析

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) { // Hold a wake lock until the power key is released. // mPowerKeyWakeLock为PARTIAL_WAKE_LOCK级别的锁 if (!mPowerKeyWakeLock.isHeld()) { //将调用到PMS的acquire WakeLock流程 mPowerKeyWakeLock.acquire(); } // Cancel multi-press detection timeout. //处理多次按power键的场景 //每次power up时，发送MSG_POWER_DELAYED_PRESS的延迟消息 //如果延迟消息被处理，说明一次完整的Power键处理结束（按下去，弹起来） if (mPowerKeyPressCounter != 0) { mHandler.removeMessages(MSG_POWER_DELAYED_PRESS); }// Detect user pressing the power button in panic when an application has // taken over the whole screen.boolean panic = mImmersiveModeConfirmation.onPowerKeyDown(interactive, SystemClock.elapsedRealtime(), isImmersiveMode(mLastSystemUiFlags)); if (panic) { mHandler.post(mHiddenNavPanic); }// Latch power key state to detect screenshot chord. //屏状态，满足触发截屏的条件则触发截屏功能if (interactive & & !mScreenshotChordPowerKeyTriggered & & (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) { mScreenshotChordPowerKeyTriggered = true; mScreenshotChordPowerKeyTime = event.getDownTime(); //触发截屏功能 interceptScreenshotChord(); }// Stop ringing or end call if configured to do so when power is pressed.TelecomManager telecomManager = getTelecommService(); boolean hungUp = false; if (telecomManager != null) { if (telecomManager.isRinging()) { // Pressing Power while there\'s a ringing incoming // call should silence the ringer. //有电话拨入且响铃状态，默认设置静音 telecomManager.silenceRinger(); } else if ((mIncallPowerBehavior & Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0& & telecomManager.isInCall() & & interactive) {// Otherwise, if "Power button ends call" is enabled, // the Power button will hang up any current active call. //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 hungUp = telecomManager.endCall(); } } GestureLauncherService gestureService = LocalServices.getService( GestureLauncherService.class); boolean gesturedServiceIntercepted = false; if (gestureService != null) { //手势对应的服务，尝试拦截处理Power键动作事件 gesturedServiceIntercepted = gestureService.interceptPowerKeyDown(event, interactive,mTmpBoolean); if (mTmpBoolean.value & & mGoingToSleep) { mCameraGestureTriggeredDuringGoingToSleep = true; } }// If the power key has still not yet been handled, then detect short // press, long press, or multi press and decide what to do. mPowerKeyHandled = hungUp ||mScreenshotChordVolumeDownKeyTriggered||mScreenshotChordVolumeUpKeyTriggered || gesturedServiceIntercepted; //Power键事件未被消耗掉 if (!mPowerKeyHandled) { //屏幕还是亮的 if (interactive) { // When interactive, we\'re already awake. // Wait for a long press or for the button to be released to decide what to do. //1、判断是否支持长按的行为 if (hasLongPressOnPowerBehavior()) { //2、亮屏状态，长按Power键将触发MSG_POWER_LONG_PRESS消息Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS); msg.setAsynchronous(true); mHandler.sendMessageDelayed(msg, ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout()); }} else { //3、灭屏状态先唤醒系统，这个会调用到PMS的wakeUp wakeUpFromPowerKey(event.getDownTime()); //支持熄屏长按，mSupportLongPressPowerWhenNonInteractive读资源文件得到，默认为falseif (mSupportLongPressPowerWhenNonInteractive & & hasLongPressOnPowerBehavior()) {Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS); msg.setAsynchronous(true); mHandler.sendMessageDelayed(msg,ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout()); mBeganFromNonInteractive = true; } else {//默认返回1final int maxCount = getMaxMultiPressPowerCount(); if (maxCount < = 1) {//息屏时，按下power键（不弹起），仅消耗掉该事件mPowerKeyHandled = true; } else { mBeganFromNonInteractive = true; } } } } }

1）是否支持长按hasLongPressOnPowerBehavior （）hasLongPressOnPowerBehavior负责判断终端是否支持长按的行为，通过读取系统的配置文件来判断。

private boolean hasLongPressOnPowerBehavior() {return getResolvedLongPressOnPowerBehavior() != LONG_PRESS_POWER_NOTHING; }private int getResolvedLongPressOnPowerBehavior() { //取决与系统属性"factory.long_press_power_off"，此处默认为false if (FactoryTest.isLongPressOnPowerOffEnabled()) { return LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM; } return mLongPressOnPowerBehavior; }从上面的代码可以看出，终端是否支持长按行为，最终将由mLongPressOnPowerBehavior决定。 ......... mLongPressOnPowerBehavior = mContext.getResources().getInteger(com.android.internal.R.integer.config_longPressOnPowerBehavior); .........

mLongPressOnPowerBehavior将在PhoneWindowManager初始化时，通过读取资源文件（定义在frameworks/base/res/res/values/config.xm 中）得到，一般情况下应该为1。于是，hasLongPressOnPowerBehavior的值返回true，即终端支持Power键长按。
config.xm 中定义的power按键的长按、短按、双击、三联按的行为

文章图片

2）长按MSG_POWER_LONG_PRESS的处理从上面的代码，在亮屏时按Power键，会触发延迟的MSG_POWER_LONG_PRESS消息。如果在MSG_POWER_LONG_PRESS超时前，Power键未被释放掉，那么此次操作被定义为长按Power键。

文章图片

MSG_POWER_LONG_PRESS对应的处理函数为powerLongPress：

private void powerLongPress() { //也是由资源文件得到，默认为1，即LONG_PRESS_POWER_GLOBAL_ACTIONSfinal int behavior = getResolvedLongPressOnPowerBehavior(); switch (behavior) { case LONG_PRESS_POWER_NOTHING: break; case LONG_PRESS_POWER_GLOBAL_ACTIONS: mPowerKeyHandled = true; //performHapticFeedbackLw进行震动反馈，不同的事件，定义了不同的震动模式 if (!performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false)) { //如果没有震动反馈，尝试声音反馈，例如响一下按键音 performAuditoryFeedbackForAccessibilityIfNeed(); } //弹出选择关机还是重启的对话框 showGlobalActionsInternal(); break; case LONG_PRESS_POWER_SHUT_OFF: case LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM: mPowerKeyHandled = true; performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false); //弹出系统关机界面 sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS); //调关机接口 mWindowManagerFuncs.shutdown(behavior == LONG_PRESS_POWER_SHUT_OFF); break; ......... } }

3）唤醒系统点亮屏幕wakeUpFromPowerKey （）在息屏的状态下按下Power键，将调用wakeUpFromPowerKey函数唤醒系统：

private void wakeUpFromPowerKey(long eventTime) { //从config.xml读mAllowTheaterModeWakeFromPowerKey默认为true wakeUp(eventTime, mAllowTheaterModeWakeFromPowerKey, "android.policy:POWER"); } private boolean wakeUp(long wakeTime, boolean wakeInTheaterMode, String reason) { //取数据库的值 final boolean theaterModeEnabled = isTheaterModeEnabled(); //按Power键时，条件返回false if (!wakeInTheaterMode & & theaterModeEnabled) { return false; }if (theaterModeEnabled) { Settings.Global.putInt(mContext.getContentResolver(), Settings.Global.THEATER_MODE_ON, 0); } //最终将调用到PMS的wakeUp函数 mPowerManager.wakeUp(wakeTime, reason); return true; }我们跟进一下PMS的wakeUp函数：public void wakeUp(long eventTime, String reason, String opPackageName) { ..........try { wakeUpInternal(eventTime, reason, uid, opPackageName, uid); } finally { ............... } }private void wakeUpInternal(long eventTime, String reason, int uid, String opPackageName, int opUid) { synchronized (mLock) { //更新Wakefullness的状态为WAKEFULNESS_AWAKE，记录一次UserActivity if (wakeUpNoUpdateLocked(eventTime, reason, uid, opPackageName, opUid)) { //如之前博客所述，对整个电源状态进行一次调整，将在需要时点亮屏幕 updatePowerStateLocked(); } } }

2、Power抬起（interceptPowerKeyUp ） A: Power抬起时序图
interceptPowerKeyUp处理松开Power键后的流程：
【Android 7.0Power 按键处理流程】

文章图片

B: Power抬起代码分析

private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) { //事件被取消，或者在按下Power键时，该事件已被消耗掉 //那么就不用继续处理 final boolean handled = canceled || mPowerKeyHandled; mScreenshotChordPowerKeyTriggered = false; //退出截屏 cancelPendingScreenshotChordAction(); //取消MSG_POWER_LONG_PRESS事件，即在一定事件内Power键弹起，则表示这一次不是长按Power键cancelPendingPowerKeyAction(); //从之前的代码，我们知道除了特殊功能外灭屏按Power键或亮屏长按时，均会消耗掉Power事件因此，只有亮屏短按Power键需要进行处理 if (!handled) { // Figure out how to handle the key now that it has been released.mPowerKeyPressCounter += 1; final int maxCount = getMaxMultiPressPowerCount(); final long eventTime = event.getDownTime(); if (mPowerKeyPressCounter < maxCount) { // This could be a multi-press.Wait a little bit longer to confirm. // Continue holding the wake lock. // 与之前interceptPowerKeyDown，处理Power键被多次按下场景对应 // 每次被按下，均发送MSG_POWER_DELAYED_PRESS消息 // 实际上maxCount为1，不会进入该分支 Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS, interactive ? 1 : 0, mPowerKeyPressCounter, eventTime); msg.setAsynchronous(true); mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout()); return; } //1、No other actions.Handle it immediately. powerPress(eventTime, interactive, mPowerKeyPressCounter); }// 2、Done.Reset our state. finishPowerKeyPress(); }

1）powerPress
powerPress函数根据屏幕状态和配置的条件，如果亮屏状态下短按power按键则调用PMS的goToSleep（）函数，执行灭屏并将系统休眠。

private void powerPress(long eventTime, boolean interactive, int count) {if (mScreenOnEarly & & !mScreenOnFully) { Slog.i(TAG, "Suppressed redundant power key press while " + "already in the process of turning the screen on."); return; }if (count == 2) { //原生不进入 powerMultiPressAction(eventTime, interactive, mDoublePressOnPowerBehavior); } else if (count == 3) {//原生不进入 powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior); } else if (interactive & & !mBeganFromNonInteractive) { //亮屏时，将进入该分支 //mShortPressOnPowerBehavior被配置为1 switch (mShortPressOnPowerBehavior) { case SHORT_PRESS_POWER_NOTHING: break; case SHORT_PRESS_POWER_GO_TO_SLEEP: //最终调用到PMS的goToSleep函数 mPowerManager.goToSleep(eventTime, PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0); break; ............... } } }在亮屏状态下，短按一下Power键，最终将调用到PMS的goToSleep函数，使终端进入到休眠状态，与实际情况一致。 PMS的goToSleep函数public void goToSleep(long eventTime, int reason, int flags) { ............try { goToSleepInternal(eventTime, reason, flags, uid); } finally { ...............} } private void goToSleepInternal(long eventTime, int reason, int flags, int uid) {synchronized (mLock) {//没有触发用户事件，将mWakefullness置为WAKEFULNESS_DOZINGif (goToSleepNoUpdateLocked(eventTime, reason, flags, uid)) {//执行整体的电源状态更新，将熄灭屏幕updatePowerStateLocked(); }}

2）finishPowerKeyPress每当处理一次完整的Power键按下、弹出操作后，interceptPowerKeyUp调用finishPowerKeyPress进行最后的状态复位操作：

private void finishPowerKeyPress() {mBeganFromNonInteractive = false; mPowerKeyPressCounter = 0; if (mPowerKeyWakeLock.isHeld()) { mPowerKeyWakeLock.release(); } }

从代码可以看出，主要的工作其实就是将状态变量恢复为初始值，同时释放掉最初申请的锁。
三、Power按键处理总流程按键处理的总流程如下图：