Android中对闹钟Alarm的事件处理

之前的博文一直在持续分享Phone相关的知识也算是知识笔记，但在工作中难免遇到其他模块的一些问题，因此在解决这些问题的时候顺手将这些知识记录并分享出来。有些知识在不知道的时候会觉得非常难，当了解之后便会觉得非常easy。同一时候部分知识也是具有时效性的，比方随着Android版本号的更迭。Phone的架构变化等等，因此希望自己的笔记可以帮助到一些童鞋。这样就足够了。

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Android中假设闹钟响起时。而应用须要对此做一些处理应该怎么办呢？首先我们须要接收到该事件。之后再考虑是关闭(stop)还是小睡(snooze)。

在代码packages/apps/DeskClock/src/com/android/deskclock/alarms/AlarmService.java 中有例如以下描写叙述：

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";

通过查看凝视能够知道，系统提供了两个Action用于广播闹钟事件，包含：com.android.deskclock.ALARM_ALERT和com.android.deskclock.ALARM_DONE，即当闹钟响起时触发com.android.deskclock.ALARM_ALERT，而当闹钟停止或者小睡时触发com.android.deskclock.ALARM_DONE。也就说须要监听广播事件就注冊一个广播监听器：

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

这里的mReceiver是BroadCastReceiver的对象，在onReceive中处理事件。当闹钟响起时，弹出的界面是AlarmActivity.java路径位于：packages/apps/DeskClock/src/com/android/deskclock/alarms/AlarmActivity.java。在该类中提供了两个重要的闹钟操作接口，即stop和snooze，能够看到例如以下描写叙述：

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";

该方法提供了两个广播接收的接口各自是com.android.deskclock.ALARM_SNOOZE和com.android.deskclock.ALARM_DISMISS，前者用于snooze后者用于stop。在AlarmActivity中能够看到对该action的处理，例如以下：

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    };

也就是说能够在代码中通过使用广播的方式来控制闹钟的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);
}

最后附上Demo。当闹钟响起时接收并将其Stop/Snooze，代码例如以下：

    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");
            }
        }
    }

这里可能有的人会感觉奇怪，为什么不直接调用stopAlarm和snoozeAlarm而是使用handler的sendEmptyMessageDelayed方法。

假设直接使用stopAlarm和snoozeAlarm方法会没有效果。最少须要延迟15ms才会有作用。

最后加上一些英文的翻译，以便国外的童鞋也能获得一些帮助。

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