Java BroadcastReceiver 与 WakefulBroadcastReceiver

BroadcastReceiver Vs WakefulBroadcastReceiver

提问by user2107111

Can somebody explain what the exact difference is between BroadcastReceiverand WakefulBroadcastReceiver?

有人能解释一下BroadcastReceiver和之间的确切区别WakefulBroadcastReceiver吗？

In what situations would we have to use each Receiver class?

在什么情况下我们必须使用每个 Receiver 类？

采纳答案by Mehul Joisar

There is only one difference between BroadcastReceiverand WakefulBroadcastReceiver.

BroadcastReceiver和之间只有一个区别WakefulBroadcastReceiver。

When you receive the broadcast inside onReceive()method,

当你收到广播里面的onReceive()方法时，

Suppose,

认为，

BroadcastReceiver:

广播接收器：

• It is not guaranteedthat CPU will stay awakeif you initiate some long running process. CPU may go immediately back to sleep.

• 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 可能会立即返回休眠状态。

WakefulBroadcastReceiver:

唤醒广播接收器：

• It is guaranteedthat CPU will stay awakeuntil you fire completeWakefulIntent.

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

Example:

例子：

Here, when you receive broadcast, you are starting a service, as you are using WakefulBroadcastReceiver, it will hold wakelockand won't let the CPU sleep until you finish the work inside service and fire completeWakefulIntent

在这里，当您收到广播时，您正在启动一个服务，正如您正在使用的那样WakefulBroadcastReceiver，它会保持wakelock并且不会让 CPU 休眠，直到您完成服务内部的工作并触发completeWakefulIntent

Code:

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);
    }
}