Android Location not returning Location from Custom Class

问题

I have my own location class. I have an odds result that when I search for the GPS location using my class, I get 0, 0 back.

Whereas if I search the getLastKnown function in location manager for GPS, I get the forced value:

    public Location getGPSloc(Context c){
    isGPSavailable(c);
    if(gps_enabled)
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5000, 0, locationListenerGps);
    timerGPS  = new Timer();
    timerGPS.schedule(new GetLastLocationGPS(), 45000);
    return gpsLoc;  
}

This is the class that I'm calling from outside the function, I am using this.getApplicationContext() in the call. This is GetLastLocationGPS():

    class GetLastLocationGPS extends TimerTask {
    @Override
    public void run() {
         lm.removeUpdates(locationListenerGps);
         if(gps_enabled){
             gpsLoc = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);}
         else{
             gpsLoc = null;
         }

    }
}

Here is the listener:

    LocationListener locationListenerGps = new LocationListener() {
    @Override
    public void onLocationChanged(Location location) {
        timerGPS.cancel();
        gpsLoc = location; 
        lm.removeUpdates(this);
    }
    @Override
    public void onProviderDisabled(String provider) {}
    @Override
    public void onProviderEnabled(String provider) {}
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {}
};

When I call MyLocationInstance.getGPSloc(this.getApplicationContext()) the return value is always 0, 0. I have a forced value of 83 43 that I sent to the emulator and appears if I sub in LocationManagerInstance.getLastKnownLocation(LM.GPS);

I have no idea why this method won't fetch the location.

Is it because in theory the timer is still running when the call happens? That's the only way I can come up with an answer. Any other ideas?

回答1:

I'm not sure what is your problem but this is my code which is under load and fully functional.

Since this class extends from Fragment then it can act as parent of your fragment. There is a listener that your class can get new location after each interval.

public class LocationFinderFragment extends Fragment implements
        GooglePlayServicesClient.ConnectionCallbacks,
        GooglePlayServicesClient.OnConnectionFailedListener {

    public interface OnNewLocationFoundListener {
        public void OnNewLocationFound(Location location);
    }

    private static final String TAG = "LocationFinderFragment";
    private static final long DEFAULT_UPDATE_LOCATION_INTERVAL = 30 * 1000; // update every 30 seconds
    private static final long DEFAULT_TERMINATE_SAT_FINDING = 1 * 60 * 60 * 1000; // for 1 hour

    private OnNewLocationFoundListener listener;  // Listener of fragments
    private OnNewLocationFoundListener listener2; // Listener of MainFragmentHolder
    private Context context;
    private LocationClient mLocationClient;
    private static double lat = 0;
    private static double lng = 0;
    private static long lastTime = 0;

    private LocationListener mLocationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            if(location == null)
                return;

            if(lat == location.getLatitude()  &&  lng == location.getLongitude()) {
                Log.e(TAG, "location not changed.");
                return;
            }

            lat = location.getLatitude();
            lng = location.getLongitude();
            Log.i(TAG, "Location changed to (" + lat + ", " + lng + ")");

            // Ask fragment to get new data and update screen
            listener.OnNewLocationFound(location);

            // Display toast notification every minute (instead of every 30 seconds)
            DateTime time = new DateTime();
            long currentTime = time.getMillis();
            if(currentTime > lastTime + 1 * 60 * 1000) {
                listener2.OnNewLocationFound(location);
                lastTime = currentTime;
            }
        }
    };

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        try {
            listener2 = (OnNewLocationFoundListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString() + " must implement OnNewLocationFoundListener interface.");
        }

        Log.i(TAG, "Fragment attached to activity.");
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        // Getting context
        context = getActivity().getApplicationContext();

        // Get location manager
        mLocationClient = new LocationClient(context, this, this);
    }

    @Override
    public void onResume() {
        super.onResume();

        // Get location
        if(mLocationClient != null)
            mLocationClient.connect();
    }

    @Override
    public void onPause() {
        super.onPause();

        // remove listener in order to save resource
        if(mLocationClient != null)
            mLocationClient.disconnect();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        // remove listener in order to save resource
        if(mLocationClient != null)
            mLocationClient.disconnect();
    }

    @Override
    public void onConnected(Bundle bundle) {
        Log.i(TAG, "Location Connected.");
        // Get last known location
        Location lastLocation = mLocationClient.getLastLocation();
        mLocationListener.onLocationChanged(lastLocation);

        if(!SpGodMode.isLocationModeEnabled(context)) {
            // Create location request
            LocationRequest locationRequest = LocationRequest.create()
                    .setInterval(DEFAULT_UPDATE_LOCATION_INTERVAL)
                    .setExpirationDuration(DEFAULT_TERMINATE_SAT_FINDING)
                    .setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
            mLocationClient.requestLocationUpdates(locationRequest, mLocationListener);
        } else {
            String strLoc = SpGodMode.getLocation(context);
            if(strLoc != null) {
                String lat = strLoc.substring(0, strLoc.indexOf(","));
                String lng = strLoc.substring(strLoc.indexOf(",") + 1);
                Location location = new Location("");
                try {
                    location.setLatitude(Double.parseDouble(lat));
                    location.setLongitude(Double.parseDouble(lng));
                    mLocationListener.onLocationChanged(location);
                } catch (NumberFormatException e) {
                    Log.e(TAG, "Wrong lat/lng for parsing as Double.");
                    Toast.makeText(context, "Wrong lat/lng", Toast.LENGTH_SHORT).show();
                }
            }
        }
    }

    @Override
    public void onDisconnected() {
        Log.i(TAG, "Location Disconnected.");
        if(mLocationClient != null  &&  mLocationClient.isConnected())
            mLocationClient.removeLocationUpdates(mLocationListener);
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.e(TAG, "Connection failed listener.");
    }

    public void setLocationListener(OnNewLocationFoundListener listener) {
        this.listener = listener;
    }

    public void disconnectLocation() {
        mLocationClient.disconnect();
    }
}

来源：https://stackoverflow.com/questions/18049099/android-location-not-returning-location-from-custom-class