BroadcastReceiver与WakefulBroadcastReceiver

Question

有人可以解释BroadcastReceiver和WakefulBroadcastReceiver之间的确切区别吗？

在什么情况下我们必须使用每个Receiver类？

Answer 1

BroadcastReceiver和WakefulBroadcastReceiver之间只有一个区别。

当您在onReceive()方法中收到广播时，

假设，

BroadcastReceiver ：

• 无法保证 CPU将保持清醒如果您启动一些长时间运行的进程。 CPU可能会立即重新入睡。

WakefulBroadcastReceiver ：

• 保证 CPU将保持清醒，直到您触发completeWakefulIntent。

示例：

在这里，当您收到广播时，您正在启动一项服务，因为您正在使用WakefulBroadcastReceiver，它将保留wakelock并且不会让CPU睡眠，直到您完成内部工作服务和火灾completeWakefulIntent

代码：

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);
    }
}