ShutdownThread - 动画 & 音乐
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?? ? ?在android原生的关机流程里面是没有声音和 自定义动画的借口，因此为了实现这两个功能需要找到相应的地方并采用合适的方式进行处理。
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在关机的ShutdownThread类里面有两个很重要的方法，一个是beginShutdownSequence，解析如下：
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?? ?private static void beginShutdownSequence(Context context) {
?? ? ? ?synchronized (sIsStartedGuard) {
?? ? ? ? ? ?sIsStarted = true;
?? ? ? ?}
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?? ? ? ?// throw up an indeterminate system dialog to indicate radio is
?? ? ? ?// shutting down.
?? ? ? ?//动画开始?
?? ? ? ?//这里也是可以加入声音的播放流程，（这里要考虑到几点：声音与动画的同步；需要避免蓝牙等断开操作导致的声音不连续）
?? ? ? ?ProgressDialog pd = new ProgressDialog(context);
?? ? ? ?pd.setTitle(context.getText(com.android.internal.R.string.power_off));
?? ? ? ?pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
?? ? ? ?pd.setIndeterminate(true);
?? ? ? ?pd.setCancelable(false);
?? ? ? ?pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
?? ? ? ?if (!context.getResources().getBoolean(
?? ? ? ? ? ? ? ?com.android.internal.R.bool.config_sf_slowBlur)) {
?? ? ? ? ? ?pd.getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
?? ? ? ?}
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?? ? ? ?pd.show();
?? ? ?
?//动画结束，需要在这里加入自定的view并进行显示。这里的view需要注意横竖屏的转化，让其显示唯一，后面的代码则是启动关机的动作。
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?? ? ? ?// start the thread that initiates shutdown
?? ? ? ?sInstance.mContext = context;
?? ? ? ?sInstance.mPowerManager = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
?? ? ? ?sInstance.mWakeLock = null;
?? ? ? ?if (sInstance.mPowerManager.isScreenOn()) {
?? ? ? ? ? ?try {
?? ? ? ? ? ? ? ?sInstance.mWakeLock = sInstance.mPowerManager.newWakeLock(
?? ? ? ? ? ? ? ? ? ? ? ?PowerManager.FULL_WAKE_LOCK, "Shutdown");
?? ? ? ? ? ? ? ?sInstance.mWakeLock.acquire();
?? ? ? ? ? ?} catch (SecurityException e) {
?? ? ? ? ? ? ? ?Log.w(TAG, "No permission to acquire wake lock", e);
?? ? ? ? ? ? ? ?sInstance.mWakeLock = null;
?? ? ? ? ? ?}
?? ? ? ?}
?? ? ? ?sInstance.mHandler = new Handler() {
?? ? ? ?};
?? ? ? ?sInstance.start();
?? ?}
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第二个就是run方法，该方法决定了一个完整的关机流程所需要的时间。设置时间为最少10秒，其实该段代码在无声音和动画的情况下可以在5秒内执行完毕。如果考虑到声音就要注意了，因为很有可能产生破音（就是关机的最后一刻会产生比较尖锐的声音）
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public void run() { boolean bluetoothOff; boolean radioOff; BroadcastReceiver br = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { // We don't allow apps to cancel this, so ignore the result. actionDone(); } }; Log.i(TAG, "Sending shutdown broadcast..."); // First send the high-level shut down broadcast. mActionDone = false; mContext.sendOrderedBroadcast(new Intent(Intent.ACTION_SHUTDOWN), null, br, mHandler, 0, null, null); ? //从这里开始 final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME; synchronized (mActionDoneSync) { while (!mActionDone) { long delay = endTime - SystemClock.elapsedRealtime(); if (delay <= 0) { Log.w(TAG, "Shutdown broadcast timed out"); break; } try { mActionDoneSync.wait(delay); } catch (InterruptedException e) { } } } ?//到这里结束，这段时间的延迟是可以缩短的，当然是会有些问题。当然如果是为了更快的关机，这些问题就可以通过动画和声音避免掉。 ?
Log.i(TAG, "Shutting down activity manager..."); final IActivityManager am = ActivityManagerNative.asInterface(ServiceManager.checkService("activity")); if (am != null) { try { am.shutdown(MAX_BROADCAST_TIME); } catch (RemoteException e) { } }//从这里开始
final ITelephony phone = ITelephony.Stub.asInterface(ServiceManager.checkService("phone")); final IBluetooth bluetooth = IBluetooth.Stub.asInterface(ServiceManager.checkService( BluetoothAdapter.BLUETOOTH_SERVICE)); final IMountService mount = IMountService.Stub.asInterface( ServiceManager.checkService("mount")); //到这里结束，可以通过以上的方式得到一只运行在后台的系统服务。蓝牙耳机也就是通过这种方式获取，然后再判断声音如何播放 try { bluetoothOff = bluetooth == null || bluetooth.getBluetoothState() == BluetoothAdapter.STATE_OFF; if (!bluetoothOff) { Log.w(TAG, "Disabling Bluetooth..."); bluetooth.disable(false); // disable but don't persist new state } } catch (RemoteException ex) { Log.e(TAG, "RemoteException during bluetooth shutdown", ex); bluetoothOff = true; } // try { radioOff = phone == null || !phone.isRadioOn(); if (!radioOff) { Log.w(TAG, "Turning off radio..."); phone.setRadio(false); } } catch (RemoteException ex) { Log.e(TAG, "RemoteException during radio shutdown", ex); radioOff = true; } Log.i(TAG, "Waiting for Bluetooth and Radio..."); // Wait a max of 32 seconds for clean shutdown for (int i = 0; i < MAX_NUM_PHONE_STATE_READS; i++) { if (!bluetoothOff) { try { bluetoothOff = bluetooth.getBluetoothState() == BluetoothAdapter.STATE_OFF; } catch (RemoteException ex) { Log.e(TAG, "RemoteException during bluetooth shutdown", ex); bluetoothOff = true; } } if (!radioOff) { try { radioOff = !phone.isRadioOn(); } catch (RemoteException ex) { Log.e(TAG, "RemoteException during radio shutdown", ex); radioOff = true; } } if (radioOff && bluetoothOff) { Log.i(TAG, "Radio and Bluetooth shutdown complete."); break; } SystemClock.sleep(PHONE_STATE_POLL_SLEEP_MSEC); } // Shutdown MountService to ensure media is in a safe state IMountShutdownObserver observer = new IMountShutdownObserver.Stub() { public void onShutDownComplete(int statusCode) throws RemoteException { Log.w(TAG, "Result code " + statusCode + " from MountService.shutdown"); actionDone(); } }; Log.i(TAG, "Shutting down MountService"); // Set initial variables and time out time. mActionDone = false; final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME; synchronized (mActionDoneSync) { try { if (mount != null) { mount.shutdown(observer); } else { Log.w(TAG, "MountService unavailable for shutdown"); } } catch (Exception e) { Log.e(TAG, "Exception during MountService shutdown", e); } while (!mActionDone) { long delay = endShutTime - SystemClock.elapsedRealtime(); if (delay <= 0) { Log.w(TAG, "Shutdown wait timed out"); break; } try { mActionDoneSync.wait(delay); } catch (InterruptedException e) { } } } if (mReboot) { Log.i(TAG, "Rebooting, reason: " + mRebootReason); try { Power.reboot(mRebootReason); } catch (Exception e) { Log.e(TAG, "Reboot failed, will attempt shutdown instead", e); } } else if (SHUTDOWN_VIBRATE_MS > 0) { // vibrate before shutting down Vibrator vibrator = new Vibrator(); vibrator.vibrate(SHUTDOWN_VIBRATE_MS); // vibrator is asynchronous so we need to wait to avoid shutting down too soon. try { Thread.sleep(SHUTDOWN_VIBRATE_MS); } catch (InterruptedException e) { } } //最后在这里一定要注意，声音是否播放完毕。如果没有完毕则要延时后再执行下面的命令，否则会产生破音。 // Shutdown power Log.i(TAG, "Performing low-level shutdown..."); Power.shutdown(); }?
?? ? run方法的整个关机过程包括上面的方法不能产生任何错误，即便是try catch处理过也不行，这样会导致机器调用reboot的命令，很无奈的！！ ?例如Thread.sleep就有可能产生错误，源码中就有这样的隐患。建议使用SystemClock.sleep替换，这样就可以避免机器重启的隐患。
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