BroadcastReceiver与WakefulBroadcastReceiver

Question

有人可以解释一下BroadcastReceiver和之间的确切区别WakefulBroadcastReceiver吗？

在什么情况下我们必须使用每个Receiver类？

Answer 1

BroadcastReceiver和之间只有一个区别WakefulBroadcastReceiver.

当你收到广播里面的onReceive()方法,

假设,

BroadcastReceiver:

• 它不保证该CPU将保持清醒,如果你启动一些长时间运行的进程.CPU可能会立即重新进入睡眠状态.

WakefulBroadcastReceiver:

• 这是保证该CPU将保持清醒,直到你开除completeWakefulIntent.

例:

在这里,当你收到广播时,你正在启动一项服务,正如你所使用的那样WakefulBroadcastReceiver,它将保持wakelock并且不会让CPU睡眠,直到你完成服务内部的工作并开火completeWakefulIntent

码:

public class SimpleWakefulReceiver extends WakefulBroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        // This is the Intent to deliver to our service.
        Intent service = new Intent(context, SimpleWakefulService.class);

        // Start the service, keeping the device awake while it is launching.
        Log.i("SimpleWakefulReceiver", "Starting service @ " + SystemClock.elapsedRealtime());
        startWakefulService(context, service);
    }
}

class SimpleWakefulService extends IntentService {
    public SimpleWakefulService() {
        super("SimpleWakefulService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        // At this point SimpleWakefulReceiver is still holding a wake lock
        // for us.  We can do whatever we need to here and then tell it that
        // it can release the wakelock.  This sample just does some slow work,
        // but more complicated implementations could take their own wake
        // lock here before releasing the receiver's.
        //
        // Note that when using this approach you should be aware that if your
        // service gets killed and restarted while in the middle of such work
        // (so the Intent gets re-delivered to perform the work again), it will
        // at that point no longer be holding a wake lock since we are depending
        // on SimpleWakefulReceiver to that for us.  If this is a concern, you can
        // acquire a separate wake lock here.
        for (int i=0; i<5; i++) {
            Log.i("SimpleWakefulReceiver", "Running service " + (i+1)
                    + "/5 @ " + SystemClock.elapsedRealtime());
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
            }
        }
        Log.i("SimpleWakefulReceiver", "Completed service @ " + SystemClock.elapsedRealtime());
        SimpleWakefulReceiver.completeWakefulIntent(intent);
    }
}