1. 简介
Android4.x在Framework的PhoneWindowManager对Power(KeyEvent.KEYCODE_POWER)和Home(KeyEvent.KEYCODE_HOME)键做了处理,不会把这些键传送上层应用程序。如需要把这些键发送给Activity和Service,需要在PhoneWindowManager处理这些键时“发送一个广播出去,然后在应用程序接收到广播后做处理”。
如果应用程序只需要获取获取待机、唤醒、关机、网络状态变化消息,则可监听以下广播消息:
1) 待机:
广播消息:android.intent.action.SCREEN_OFF (代码)
2) 唤醒:
广播消息:android.intent.action.SCREEN_ON (代码)
3) 关机:
广播消息:android.intent.action.ACTION_SHUTDOWN (XML或代码)
4) 网络状态变化:
广播消息:android.net.conn.CONNECTIVITY_CHANGE (XML或代码)
然后调用下面的isNetworkAvailable获取当前网络状态。
public static boolean isNetworkAvailable(Context context) {
ConnectivityManager mgr = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo[] info = mgr.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {
if (info[i].getState() == NetworkInfo.State.CONNECTED) {
return true;
}
}
}
return false;
}
2. 短按Power键处理流程
短按Power键处理流程如下图所示:
3. 长按Power键处理流程
长按Power键处理流程如下图所示:
3.1 Message超时处理流程
如果长按Power键(超过500ms),则此消息(Message.callback为mPowerLongPress)将被执行。mPowerLongPress (PhoneWindowManager.java)定义如下:
private final Runnable mPowerLongPress = new Runnable() { public void run() { // The context isn't read if (mLongPressOnPowerBehavior < 0) { mLongPressOnPowerBehavior = mContext.getResources().getInteger( com.android.internal.R.integer.config_longPressOnPowerBehavior); } switch (mLongPressOnPowerBehavior) { case LONG_PRESS_POWER_NOTHING: break; case LONG_PRESS_POWER_GLOBAL_ACTIONS: mPowerKeyHandled = true; performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false); sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS); showGlobalActionsDialog(); break; case LONG_PRESS_POWER_SHUT_OFF: mPowerKeyHandled = true; performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false); sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS); ShutdownThread.shutdown(mContext, true); break; } } };
它是一个匿名内部类,它是一个实现Runnable的类的对象引用,因此
new Runnable() {
public void run(){
...
}
};
它包括了定义这个类(只不过这个类没有名字)和实例化这个类的对象。
当超时时,其执行流程如下图所示:
3.2 reboot系统调用流程
reboot系统调用流程如下图所示:
4. 如何处理短按和长按电源键
长按电源键:弹出关机确认对话框(KeyDown之后,如果 500ms之内,没有收到KeyUp则弹出关机确认对话框)
短按电源键:执行待机(KeyUp时执行<wmActions=4>)或唤醒(KeyDown时执行<wmActions=2>)
对于长按电源键,在PhoneWindowManager.java的interceptKeyBeforeQueueing函数中进行处理,其相关代码如下 :
case KeyEvent.KEYCODE_POWER: { result &= ~ACTION_PASS_TO_USER; if (down) { if (isScreenOn && !mPowerKeyTriggered && (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) { mPowerKeyTriggered = true; mPowerKeyTime = event.getDownTime(); interceptScreenshotChord(); } ... // Power Key down, set mPowerLongPress executing after 500ms interceptPowerKeyDown(!isScreenOn || hungUp || mVolumeDownKeyTriggered || mVolumeUpKeyTriggered); } else { mPowerKeyTriggered = false; cancelPendingScreenshotChordAction(); if (interceptPowerKeyUp(canceled || mPendingPowerKeyUpCanceled)) { result = (result & ~ACTION_POKE_USER_ACTIVITY) | ACTION_GO_TO_SLEEP; } // Power key up, remove the mPowerLongPress, that is, if user release // power key during 500ms, mPowerLongPress will not be execute, then execute sleep mPendingPowerKeyUpCanceled = false; } break; }
private void interceptPowerKeyDown(boolean handled) { mPowerKeyHandled = handled; if (!handled) { mHandler.postDelayed(mPowerLongPress, ViewConfiguration.getGlobalActionKeyTimeout()/*500ms*/); } } private boolean interceptPowerKeyUp(boolean canceled) { if (!mPowerKeyHandled) { mHandler.removeCallbacks(mPowerLongPress); return !canceled; } return false; }