android - How to get data from service to activity

Question

In my app I have an activity and a service... The service will broadcast messages gathered from data from GPS... The Activity should receive the broadcast messages and update the UI...

my code

public class LocationPollerDemo extends Activity {
    private static final int PERIOD = 10000; // 30 minutes
    private PendingIntent pi = null;
    private AlarmManager mgr = null;
    private double lati;
    private double longi;
    private ServiceReceiver serviceReceiver;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mgr = (AlarmManager) getSystemService(ALARM_SERVICE);

        Intent i = new Intent(this, LocationPoller.class);

        i.putExtra(LocationPoller.EXTRA_INTENT, new Intent(this, ServiceReceiver.class));
        i.putExtra(LocationPoller.EXTRA_PROVIDER, LocationManager.GPS_PROVIDER);

        pi = PendingIntent.getBroadcast(this, 0, i, 0);
        mgr.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), PERIOD, pi);

        DebugLog.logTrace("On Create Demo");
        Toast.makeText(this, "Location polling every 30 minutes begun", Toast.LENGTH_LONG).show();
        serviceReceiver = new ServiceReceiver();
        IntentFilter filter = new IntentFilter("me");
        this.registerReceiver(serviceReceiver, filter);
    }

    class ServiceReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            File log = new File(Environment.getExternalStorageDirectory(), "Location2.txt");
            DebugLog.logTrace(Environment.getExternalStorageDirectory().getAbsolutePath());

            try {
                BufferedWriter out = new BufferedWriter(new FileWriter(log.getAbsolutePath(), log.exists()));

                out.write(new Date().toString());
                out.write(" : ");

                Bundle b = intent.getExtras();
                Location loc = (Location) b.get(LocationPoller.EXTRA_LOCATION);
                String msg;

                if (loc == null) {
                    loc = (Location) b.get(LocationPoller.EXTRA_LASTKNOWN);

                    if (loc == null) {
                        msg = intent.getStringExtra(LocationPoller.EXTRA_ERROR);
                    } else {
                        msg = "TIMEOUT, lastKnown=" + loc.toString();
                    }
                } else {
                    msg = loc.toString();
                }

                if (msg == null) {
                    msg = "Invalid broadcast received!";
                }

                out.write(msg);
                out.write("\n");
                out.close();
            } catch (IOException e) {
                Log.e(getClass().getName(), "Exception appending to log file", e);
                DebugLog.logException(e);
            }
        }
    }
}

When I use this code it is not working properly... I am using ServiceReceiver class in separate file works fine.... please tell me...!!

score 61 · Accepted Answer

In my Service class I wrote this

private static void sendMessageToActivity(Location l, String msg) {
    Intent intent = new Intent("GPSLocationUpdates");
    // You can also include some extra data.
    intent.putExtra("Status", msg);
    Bundle b = new Bundle();
    b.putParcelable("Location", l);
    intent.putExtra("Location", b);
    LocalBroadcastManager.getInstance(context).sendBroadcast(intent);
}

and at the Activity side we have to receive this Broadcast message

LocalBroadcastManager.getInstance(getActivity()).registerReceiver(
            mMessageReceiver, new IntentFilter("GPSLocationUpdates"));

By this way you can send message to an Activity. here mMessageReceiver is the class in that class you will perform what ever you want....

in my code I did this....

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // Get extra data included in the Intent
        String message = intent.getStringExtra("Status");
        Bundle b = intent.getBundleExtra("Location");
        lastKnownLoc = (Location) b.getParcelable("Location");
        if (lastKnownLoc != null) {
            tvLatitude.setText(String.valueOf(lastKnownLoc.getLatitude()));
            tvLongitude
                    .setText(String.valueOf(lastKnownLoc.getLongitude()));
            tvAccuracy.setText(String.valueOf(lastKnownLoc.getAccuracy()));
            tvTimestamp.setText((new Date(lastKnownLoc.getTime())
                    .toString()));
            tvProvider.setText(lastKnownLoc.getProvider());
        }
        tvStatus.setText(message);
        // Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
    }
};

score 11 · Accepted Answer

A good way to have it is using Handler. Create a innerClass in your activity that extends Handler and Override the handleMessage method.

Then, in your ServiceReceiver class, create a handler variable and a constructor like:

public ServiceReceiver(Handler handler){
   this.handler = handler;
}

So, in your activity, create your custom handler and pass it to your service. So, when you wants to put some data to your activity, you can put handler.sendMessage() in your Service (it will call handleMessage of your innerClass).

score 7 · Accepted Answer

How to send data to Activity from IntentService ?

You don't need to bind a service if the service is meant for one way communication. For such cases using IntentService + BroadcastReceiver is quite easy.

Example:

You have a BackgroundService which calculates signal strength and sends back the data to Activity every second. And the Activity shows data in a GraphView.

How to do that?

Send data from Service

public class TrackWifiService extends IntentService {

    public TrackWifiService() {
        super("wifiService");
    }

    protected void onHandleIntent(@Nullable Intent intent) {

        sendDataToActivity()
    }

   private void sendDataToActivity()
   {
        Intent sendLevel = new Intent();
        sendLevel.setAction("GET_SIGNAL_STRENGTH");
        sendLevel.putExtra( "LEVEL_DATA","Strength_Value");
        sendBroadcast(sendLevel);

   }


}

Receive data from Service
For this, your Activity should register with a BroadcastReceiver

public class TrackWifiActivity extends AppCompatActivity {

   WifiLevelReceiver receiver;

   @Override
   public void onCreate(Bundle savedInstanceState)
   {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.track_wifi_activity_layout);
      receiver = new WifiLevelReceiver();
      registerReceiver(receiver, new IntentFilter("GET_SIGNAL_STRENGTH"));  //<----Register
   }


   @Override
   public void onStop()
   {
       super.onStop();
       unregisterReceiver(receiver);           //<-- Unregister to avoid memoryleak
   }

   class WifiLevelReceiver extends BroadcastReceiver {

       @Override
       public void onReceive(Context context, Intent intent) {

           if(intent.getAction().equals("GET_SIGNAL_STRENGTH"))
           {
              int level = intent.getIntExtra("LEVEL_DATA",0);

              // Show it in GraphView
           }
       }

   }

}

Note:

If you want to use LocalBroadcastReceiver instead of a BroadcastReceiver. You can just see check out How to convert BroadCastReceiver to LocalBroadcastReceiver

Relevant Links

See Full project
What is an IntentService?
Difference between Bound and Unbound Services

score 4 · Accepted Answer

There are three obvious ways to communicate with services

Using Intents.

Using AIDL.

Using the service object itself (as singleton).

score 0 · Accepted Answer

class MainActivity : AppCompatActivity() {
    private val sb = object :SerToBroad(){
        override fun broadcastResult(connected: String?) {
           t(connected)
        }

    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
  fun t(connected: String?)
  {
    Toast.makeText(MainActivity@this, connected, Toast.LENGTH_SHORT).show()
}
    override fun onStart() {
        super.onStart()
        startService(Intent(MainActivity@ this, MService::class.java))
        val inf = IntentFilter()
        inf.addAction(MService.ACTION)
        registerReceiver(sb, inf)
    }

    override fun onStop() {
        super.onStop()
        unregisterReceiver(sb)
    }
}
-------------------------------------
//Service class 

    class MService : Service() {
   companion object {const val   ACTION = "MY_ACTION"}
    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        val intent = Intent()
        intent.action = ACTION

        intent.putExtra("DATA", "10")

        sendBroadcast(intent)
        return super.onStartCommand(intent, flags, startId)
    }
--------------------------------------------------
broadcast

abstract class SerToBroad : BroadcastReceiver() {
    override fun onReceive(p0: Context?, p1: Intent?) {
        val rec = p1?.getStringExtra("DATA")
        broadcastResult(rec)


    }

    abstract fun broadcastResult(connected: String?)
}

android - How to get data from service to activity

5 回答 5

How to send data to Activity from IntentService ?

Example:

How to do that?

Note:

Relevant Links

Related

Reference