wakeLock does not wait for network connectivity

问题

I am using a wakelock for a alarm to update the app state regularly. The wifi takes a while to connect on Samsung phones. Also the "keep awake" option on Wifi does not work on Samsung phones (nor are they interested in fixing the issue). So when the wakelock does happen, it should wait for wifi to connect. Do I need to create a listener for the wifi connectivity for this to work, or should wakelock, kinda block for that wifi to connect ?

mWakeLock = ((PowerManager) getSystemService(POWER_SERVICE)).newWakeLock(
            PowerManager.PARTIAL_WAKE_LOCK, "Taxeeta");
    mWakeLock.acquire();
// do some network activity, in a asynctask
// in the doPost of asyscTask, release lock

Edit : The question is, that in the AsyncTask if the network is not connected, OR takes time to get on (3g takes a while to get on), the webservice call in the Async doInBackground will fail. And I will have to release the lock anyways.

Should I put in wifi/data connection listeners in ? Or is there a better way ?

回答1:

I have a similar scenario - I am woken up by an alarm, the alarm's BroadcastReceiver launches a WakefulIntentService and the service starts a scan for networks. I use a stupid way of holding on to the lock¹ - I intend to replace this with a latch. I suggest you replace the "AsyncTask" with a WakefulIntentService. Chances are the AsyncTask is not ever fired. In the WakefulIntentService you must acquire and hold on to a wifi lock - I would make this a static field of the YourWakefulIntentService - not entirely clear on this - it's a while back. If this does not work I would use a latch in the YourWakefulIntentService :

// register an alarm
Intent i = new Intent(context, YourReceiver.class);
PendingIntent alarmPendingIntent= PendingIntent.getBroadcast(context, 0, i,
            PendingIntent.FLAG_UPDATE_CURRENT);

public class YourReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        WakefulIntentService.sendWakefulWork(context, YourWIS.class);
    }
}

//pseudocode !
public class YourWIS extends WakefulIntentService { // you must add a cstor !

    @Override
    doWakefulWork() {
      acquireWifiLock();
      enableScanReceiver();
      startScan();
      serviceLatch.wait();
      releaseWifiLock();
    }
}

// in YourScanReceiver
onReceive() {
  if(action.equals(SCAN_RESULTS) {
   // do something that does not take time or start another/the same
   // WakefulIntentService
   serviceLatch.notify();
  }
}

Try first the WakefulIntentService (I guess you launch the AsyncTask from the alarm receiver). The scan receiver is a receiver registered to receive the scan results (see WifiManager docs - prefer Receivers to listeners for sleep issues)

_{1 : this is a working class - I just use a second wakeful intent service to keep the wake locks - have still to refactor it to use latches but this approach at least works (I have the second service (the Gatekeeper) wait on a monitor and have the wake lock inside the Gatekeeper. The gatekeeper also holds its CPU lock so all is fine (and ugly)}

来源：https://stackoverflow.com/questions/19360571/wakelock-does-not-wait-for-network-connectivity

标签

android-wifi

android-wake-lock