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copied!<p>I have implemented my own version of the GPSTracker class from <a href="http://www.androidhive.info/2012/07/android-gps-location-manager-tutorial/" rel="nofollow">http://www.androidhive.info/2012/07/android-gps-location-manager-tutorial/</a></p> <p>Using this you can turn on the GPS and receive a callback as soon as a valid location is available. This might take a little while depending on the location of the device but will give a much more precise and reliable position. </p> <p>With my implementation you can do something like this:</p> <pre><code>private GPSTracker gps; private FirstFixListener firstFixListener; private LocationUpdateListener locationUpdateListener; private void sendGPStoSMS() { gps = GPSTracker.getInstance(context); firstFixListener = new MyFirstFixListener(); locationUpdateListener = new MyLocationUpdateListener(); gps.startUsingGPS(firstFixListener, locationUpdateListener); } private class MyFirstFixListener implements FirstFixListener { @Override public void onFirsFixChanged(boolean hasGPSfix) { if (hasGPSfix == true) { Location position = gps.getLocation(); // send SMS with position // stop the gps and unregister callbacks gps.stopUsingGPS(firstFixListener, locationUpdateListener); } } } private class MyLocationUpdateListener implements LocationUpdateListener { @Override public void onLocationChanged(Location location) { // hand you each new location from the GPS // you do not need this as you only want to send a single position } } </code></pre> <p>And here is my implementation of GPSTracker:</p> <pre><code>public class GPSTracker extends Service implements LocationListener { private static final String TAG = "GPSTracker"; /** * Register to receive callback on first fix status * * @author Morten * */ public interface FirstFixListener { /** * Is called whenever gps register a change in first-fix availability * This is valuable to prevent sending invalid locations to the server. * * @param hasGPSfix */ public void onFirsFixChanged(boolean hasGPSfix); } /** * Register to receive all location updates * * @author Morten * */ public interface LocationUpdateListener { /** * Is called every single time the GPS unit register a new location * The location param will never be null, however, it can be outdated if hasGPSfix is not true. * * @param location */ public void onLocationChanged(Location location); } private Context mContext; // flag for GPS status private List<FirstFixListener> firstFixListeners; private List<LocationUpdateListener> locationUpdateListeners; boolean isGPSFix = false; boolean isGPSEnabled = false; private GPSFixListener gpsListener; // flag for GPS status boolean canGetLocation = false; Location location; // location double latitude; // latitude double longitude; // longitude long mLastLocationMillis; private boolean logLocationChanges; // Declaring a Location Manager protected LocationManager locationManager; /** removed again as we need multiple instances with different callbacks **/ private static GPSTracker instance; public static GPSTracker getInstance(Context context) { if (instance != null) { return instance; } return instance = new GPSTracker(context); } private GPSTracker(Context context) { this.mContext = context; gpsListener = new GPSFixListener(); firstFixListeners = new ArrayList<GPSTracker.FirstFixListener>(); locationUpdateListeners = new ArrayList<GPSTracker.LocationUpdateListener>(); } public boolean hasGPSFirstFix() { return isGPSFix; } private void addFirstFixListener(FirstFixListener firstFixListener) { this.firstFixListeners.add(firstFixListener); } private void addLocationUpdateListener( LocationUpdateListener locationUpdateListener) { this.locationUpdateListeners.add(locationUpdateListener); } private void removeFirstFixListener(FirstFixListener firstFixListener) { this.firstFixListeners.remove(firstFixListener); } private void removeLocationUpdateListener( LocationUpdateListener locationUpdateListener) { this.locationUpdateListeners.remove(locationUpdateListener); } public void setLogLocationChanges(boolean logLocationChanges) { this.logLocationChanges = logLocationChanges; } public Location getLocation() { return location; } private Location startLocationListener() { canGetLocation = false; try { locationManager = (LocationManager) mContext .getSystemService(Service.LOCATION_SERVICE); // getting GPS status isGPSEnabled = locationManager .isProviderEnabled(LocationManager.GPS_PROVIDER); if (isGPSEnabled) { if (location == null) { locationManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, this); locationManager.addGpsStatusListener(gpsListener); if (locationManager != null) { location = locationManager .getLastKnownLocation(LocationManager.GPS_PROVIDER); if (location != null) { latitude = location.getLatitude(); longitude = location.getLongitude(); } } } } else { showSettingsAlert(); } } catch (Exception e) { e.printStackTrace(); } return location; } public void stopUsingGPS(FirstFixListener firstFixListener, LocationUpdateListener locationUpdateListener) { if (firstFixListener != null) removeFirstFixListener(firstFixListener); if (locationUpdateListener != null) removeLocationUpdateListener(locationUpdateListener); stopUsingGPS(); } /** * Stop using GPS listener Calling this function will stop using GPS in your * app * */ public void stopUsingGPS() { Log.d("DEBUG", "GPS stop"); if (locationManager != null) { locationManager.removeUpdates(GPSTracker.this); location = null; if (gpsListener != null) { locationManager.removeGpsStatusListener(gpsListener); } } isGPSFix = false; location = null; } public void startUsingGPS(FirstFixListener firstFixListener, LocationUpdateListener locationUpdateListener) { Log.d("DEBUG", "GPS start"); if (firstFixListener != null) addFirstFixListener(firstFixListener); if (locationUpdateListener != null) addLocationUpdateListener(locationUpdateListener); startLocationListener(); } /** * Function to get latitude * */ public double getLatitude() { if (location != null) { latitude = location.getLatitude(); } else { Log.e("GPSTracker", "getLatitude location is null"); } // return latitude return latitude; } /** * Function to get longitude * */ public double getLongitude() { if (location != null) { longitude = location.getLongitude(); } else { Log.e("GPSTracker", "getLongitude location is null"); } // return longitude return longitude; } /** * Function to check GPS/wifi enabled * * @return boolean * */ public boolean canGetLocation() { return this.canGetLocation; } /** * Function to show settings alert dialog On pressing Settings button will * lauch Settings Options * */ public void showSettingsAlert() { AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext); // Setting Dialog Title alertDialog.setTitle("GPS settings"); // Setting Dialog Message alertDialog .setMessage("GPS is not enabled. Do you want to go to settings menu?"); // On pressing Settings button alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { Intent intent = new Intent( Settings.ACTION_LOCATION_SOURCE_SETTINGS); mContext.startActivity(intent); } }); // on pressing cancel button alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.cancel(); } }); // Showing Alert Message alertDialog.show(); } @Override public void onLocationChanged(Location location) { if ( location == null) return; this.location = location; mLastLocationMillis = SystemClock.elapsedRealtime(); canGetLocation = true; if (isGPSFix) { if (locationUpdateListeners != null) { for (LocationUpdateListener listener : locationUpdateListeners) { listener.onLocationChanged(location); } } } } @Override public void onProviderDisabled(String provider) { canGetLocation = false; } @Override public void onProviderEnabled(String provider) { } @Override public void onStatusChanged(String provider, int status, Bundle extras) { } @Override public IBinder onBind(Intent arg0) { return null; } private boolean wasGPSFix = false; // http://stackoverflow.com/questions/2021176/how-can-i-check-the-current-status-of-the-gps-receiver // answer from soundmaven private class GPSFixListener implements GpsStatus.Listener { public void onGpsStatusChanged(int event) { switch (event) { case GpsStatus.GPS_EVENT_SATELLITE_STATUS: isGPSFix = (SystemClock.elapsedRealtime() - mLastLocationMillis) < 3000; if (isGPSFix != wasGPSFix) { // only notify on changes wasGPSFix = isGPSFix; for (FirstFixListener listener : firstFixListeners) { listener.onFirsFixChanged(isGPSFix); } } break; case GpsStatus.GPS_EVENT_FIRST_FIX: // Do something. break; } } } } </code></pre>

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