BroadcastReceiver与WakefulBroadcastReceiver

有人可以解释一下BroadcastReceiver和WakefulBroadcastReceiver之间的WakefulBroadcastReceiver吗？

在什么情况下我们不得不使用每个Receiver类？

Answer 1

BroadcastReceiver和WakefulBroadcastReceiver之间只有一个区别。

当你在onReceive()方法中接收到广播onReceive() ，

假设，

BroadcastReceiver ：

• 如果您启动一些长时间运行的进程，则不能保证 CPU保持清醒状态 。 CPU可能立即回到睡眠状态。

WakefulBroadcastReceiver ：

• 保证 CPU将保持清醒，直到您启动completeWakefulIntent WinkfulIntent 。

例：

在这里，当你收到广播时，你正在启动一个服务，就像你使用的是WakefulBroadcastReceiver ，它将持有wakelock并且不会让CPUhibernate，直到你完成服务内部的工作并且completeWakefulIntent wakelock

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); } }