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WakefulBroadcastReceiver

public abstract class WakefulBroadcastReceiver
extends BroadcastReceiver

java.lang.Object
   ↳ android.content.BroadcastReceiver
     ↳ android.support.v4.content.WakefulBroadcastReceiver


Helper for the common pattern of implementing a BroadcastReceiver that receives a device wakeup event and then passes the work off to a Service, while ensuring that the device does not go back to sleep during the transition.

This class takes care of creating and managing a partial wake lock for you; you must request the WAKE_LOCK permission to use it.

Example

A WakefulBroadcastReceiver uses the method startWakefulService() to start the service that does the work. This method is comparable to startService(), except that the WakefulBroadcastReceiver is holding a wake lock when the service starts. The intent that is passed with startWakefulService() holds an extra identifying the wake lock.

import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;
import android.support.v4.content.WakefulBroadcastReceiver;
import android.util.Log;

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);
    }
}

The service (in this example, an IntentService) does some work. When it is finished, it releases the wake lock by calling completeWakefulIntent(intent). The intent it passes as a parameter is the same intent that the WakefulBroadcastReceiver originally passed in.

import android.app.IntentService;
import android.content.Intent;
import android.os.SystemClock;
import android.util.Log;

public 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);
    }
}

Summary

Public constructors

WakefulBroadcastReceiver()

Public methods

static boolean completeWakefulIntent(Intent intent)

Finish the execution from a previous startWakefulService(Context, Intent).

static ComponentName startWakefulService(Context context, Intent intent)

Do a Context.startService, but holding a wake lock while the service starts.

Inherited methods

From class android.content.BroadcastReceiver
From class java.lang.Object

Public constructors

WakefulBroadcastReceiver

WakefulBroadcastReceiver ()

Public methods

completeWakefulIntent

boolean completeWakefulIntent (Intent intent)

Finish the execution from a previous startWakefulService(Context, Intent). Any wake lock that was being held will now be released.

Parameters
intent Intent: The Intent as originally generated by startWakefulService(Context, Intent).
Returns
boolean Returns true if the intent is associated with a wake lock that is now released; returns false if there was no wake lock specified for it.

startWakefulService

ComponentName startWakefulService (Context context, 
                Intent intent)

Do a Context.startService, but holding a wake lock while the service starts. This will modify the Intent to hold an extra identifying the wake lock; when the service receives it in Service.onStartCommand, it should pass back the Intent it receives there to completeWakefulIntent(android.content.Intent) in order to release the wake lock.

Parameters
context Context: The Context in which it operate.
intent Intent: The Intent with which to start the service, as per Context.startService.
Returns
ComponentName
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