如何在广播接收器中调用服务方法？

Question

So, I have an app that starts a service. This service starts to scan for bluetooth devices with BTAdapter.startDiscovery(). Further I have a broadcastreceiver which listens for the DISCOVERY_FINISHED action. If that occurs I want to call a method from onReceive() in my service that starts the scanning process again. How am I gonna do this?

Here my receiver:

public class PollingReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        ScanBTService sBTs = new ScanBTService();
        sBTs.startScan();
    }
}

and here the service:

public class ScanBTService extends IntentService {

    private BluetoothAdapter mBTAdapter;
    private PollingReceiver mPollingReceiver;

    public ScanBTService() {
        super("ScanBTService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        final BluetoothManager btManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        mBTAdapter = btManager.getAdapter();
        mBTAdapter.startDiscovery();
    }

    public void startScan() {
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        mBTAdapter.startDiscovery();
    }
}

Answer 1

In your onReceive()-method, restart your service using the following two lines. I did not tested it out but it should work like that.

 @Override
 public void onReceive(Context context, Intent intent) {
     //ScanBTService sBTs = new ScanBTService();
     //sBTs.startScan();
     Intent i = new Intent(getApplicationContext(), ScanBTService.class);
     startService(i);
 }

You can then remove the startScan()-method, too.

Answer 2

尝试使用以下方法解决该方法：

context.startService(new Intent(context, SimpleWakefulService.class));

Answer 3

Since you are using an IntentService, you will need to create an intent for the started service to handle.

This can be achieved by the following :

Intent intent = new Intent(context, ScanBTService.class);
startService(intent);

As described here : https://developer.android.com/training/run-background-service/send-request.html

Now, if you are looking to have a service that maintains bluetooth connections, discover devices, send & receive data... If this is the case, then in my experience, i would argue the following points :

• Perhaps the best way to go about this (depending on what you're doing of course), would be to have a service running in it's own separate process which would be responsible for all of that. Check : http://developer.android.com/guide/topics/manifest/service-element.html and the tag

  android:process

• Take advantage of Android's IPC communication feature to pass & receive messages between you're main app thread and your service. Tutorial : http://www.survivingwithandroid.com/2014/01/android-bound-service-ipc-with-messenger.html .

• Create & Maintain connection quick guide : http://developer.android.com/guide/topics/connectivity/bluetooth.html#ConnectingAsAClient

Hope it helps Cheers