Android中對鬧鐘Alarm的事件處理

之前的博文一直在持續分享Phone相關的知識也算是知識筆記，但在工作中難免遇到其它模塊的一些問題，因此在解決這些問題的時候順手將這些知識記錄並分享出來。有些知識在不知道的時候會認為很難，當了解之後便會覺得很容易。同時部分知識也是具有時效性的，比如隨著Android版本的更迭，Phone的架構變化等等，因此希望自己的筆記能夠幫助到一些童鞋，這樣就足夠了。

轉載請務必注明出處：http://blog.csdn.net/yihongyuelan

Android中如果鬧鐘響起時，而應用需要對此做一些處理應該怎麼辦呢？首先我們需要接收到該事件，之後再考慮是關閉(stop)還是小睡(snooze)。在代碼packages/apps/DeskClock/src/com/android/deskclock/alarms/AlarmService.java 中有如下描述：

35    // A public action send by AlarmService when the alarm has started.
36    public static final String ALARM_ALERT_ACTION = "com.android.deskclock.ALARM_ALERT";
37
38    // A public action sent by AlarmService when the alarm has stopped for any reason.
39    public static final String ALARM_DONE_ACTION = "com.android.deskclock.ALARM_DONE";

通過查看注釋可以知道，系統提供了兩個Action用於廣播鬧鐘事件，包括：com.android.deskclock.ALARM_ALERT和com.android.deskclock.ALARM_DONE，即當鬧鐘響起時觸發com.android.deskclock.ALARM_ALERT，而當鬧鐘停止或者小睡時觸發com.android.deskclock.ALARM_DONE。也就說需要監聽廣播事件就注冊一個廣播監聽器：

IntentFilter filter = new IntentFilter();
filter.addAction("com.android.deskclock.ALARM_ALERT");
filter.addAction("com.android.deskclock.ALARM_DONE");
registerReceiver(mReceiver, filter);

這裡的mReceiver是BroadCastReceiver的對象，在onReceive中處理事件。當鬧鐘響起時，彈出的界面是AlarmActivity.java路徑位於：packages/apps/DeskClock/src/com/android/deskclock/alarms/AlarmActivity.java，在該類中提供了兩個重要的鬧鐘操作接口，即stop和snooze，可以看到如下描述：

49    // AlarmActivity listens for this broadcast intent, so that other applications
50    // can snooze the alarm (after ALARM_ALERT_ACTION and before ALARM_DONE_ACTION).
51    public static final String ALARM_SNOOZE_ACTION = "com.android.deskclock.ALARM_SNOOZE";
52
53    // AlarmActivity listens for this broadcast intent, so that other applications
54    // can dismiss the alarm (after ALARM_ALERT_ACTION and before ALARM_DONE_ACTION).
55    public static final String ALARM_DISMISS_ACTION = "com.android.deskclock.ALARM_DISMISS";

該方法提供了兩個廣播接收的接口分別是com.android.deskclock.ALARM_SNOOZE和com.android.deskclock.ALARM_DISMISS，前者用於snooze後者用於stop。在AlarmActivity中可以看到對該action的處理，如下：

184        IntentFilter filter = new IntentFilter(AlarmService.ALARM_DONE_ACTION);
185        filter.addAction(ALARM_SNOOZE_ACTION);
186        filter.addAction(ALARM_DISMISS_ACTION);
187        registerReceiver(mReceiver, filter);


118    private BroadcastReceiver mReceiver = new BroadcastReceiver() {
119        @Override
120        public void onReceive(Context context, Intent intent) {
121            String action = intent.getAction();
122            Log.v("AlarmActivity - Broadcast Receiver - " + action);
123            if (action.equals(ALARM_SNOOZE_ACTION)) {
124                snooze();
125            } else if (action.equals(ALARM_DISMISS_ACTION)) {
126                dismiss();
127            } else if (action.equals(AlarmService.ALARM_DONE_ACTION)) {
128                finish();
129            } else {
130                Log.i("Unknown broadcast in AlarmActivity: " + action);
131            }
132        }
133    };

也就是說可以在代碼中通過使用廣播的方式來控制鬧鐘的stop和snooze：

private void stopAlarm() {
    Intent intent = new Intent();
    intent.setAction("com.android.deskclock.ALARM_DISMISS");
    sendBroadcast(intent);
}
    
private void snoozeAlarm() {
    Intent intent = new Intent();
    intent.setAction("com.android.deskclock.ALARM_SNOOZE");
    sendBroadcast(intent);
}

最後附上Demo，當鬧鐘響起時接收並將其Stop/Snooze，代碼如下：

    private void stopAlarm() {
        Intent intent = new Intent();
        intent.setAction("com.android.deskclock.ALARM_DISMISS");
        sendBroadcast(intent);
    }
    
    private void snoozeAlarm() {
        Intent intent = new Intent();
        intent.setAction("com.android.deskclock.ALARM_SNOOZE");
        sendBroadcast(intent);
    }
    Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 0:
                    Log.i("Seven", "stop alarm");
                    stopAlarm();
                    break;
                case 1:
                    Log.i("Seven", "snooze alarm");
                    snoozeAlarm();
                    break;


                default:
                    break;
            }
        }
    };
    
    private void registerAlarmReceiver() {
        mReceiver = new MyReceiver();
        IntentFilter filter = new IntentFilter();
        filter.addAction("com.android.deskclock.ALARM_ALERT");
        filter.addAction("com.android.deskclock.ALARM_DONE");
        registerReceiver(mReceiver, filter);
    }


    class MyReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent.getAction().equals("com.android.deskclock.ALARM_ALERT")) {
                Log.i("Seven","ALARM_ALERT");
                mHandler.sendEmptyMessageDelayed(0,15); //stop alarm
                //mHandler.sendEmptyMessageDelayed(1,15); //snooze alarm
            }else if (intent.getAction().equals("com.android.deskclock.ALARM_DONE")) {
                Log.i("Seven","ALARM_DONE");
            }
        }
    }

這裡可能有的人會感覺奇怪，為什麼不直接調用stopAlarm和snoozeAlarm而是使用handler的sendEmptyMessageDelayed方法。如果直接使用stopAlarm和snoozeAlarm方法會沒有效果，最少需要延遲15ms才會有作用。

最後加上一些英文的翻譯，以便國外的童鞋也能獲得一些幫助。

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