Question

我正在尝试运行一个应用程序来更新屏幕上显示的地图片段上的设备位置并使其居中。地图上的蓝点显示在正确的位置，并且gps位置被锁定，但似乎永远不会调用onLocationChanged函数。

编辑：现在情况变得越来越怪异了。我让应用程序运行了一段时间（大约10分钟），它确实随机地更新了它的位置几次。它突然又停了下来。至少我知道功能是正确的。但现在我应该在哪里看看？

以下是相关代码。

public class MapaActivity extends FragmentActivity implements LocationListener{

public static GoogleMap mMap;

@Override
protected void onCreate(Bundle savedInstanceState) {

    setUpMapIfNeeded();

    mMap.setMyLocationEnabled(true);


}

public boolean setUpMapIfNeeded() {

    if (mMap == null) {

        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

        if (mMap == null) {

            setUpMap();

        }
    }
    return true;
}

private void setUpMap() {

    mMap.setMyLocationEnabled(true);

    LocationManager locationManager;

    locationManager = (LocationManager)getSystemService(LOCATION_SERVICE);

    Criteria criteria = new Criteria();

    String provider = locationManager.getBestProvider(criteria, true);

    Location location = locationManager.getLastKnownLocation(provider);

    locationManager.requestLocationUpdates(provider, 1000, 0  , this);

}



@Override
public void onLocationChanged(Location location) {

    //do some stuff

}

Answer 1

因为您没有正确注册位置udpates 。

我不知道你为什么要检查mMap == null，但试试这个：

if (mMap != null) {

            setUpMap();

        }

Answer 2

尝试以下代码。

    import android.os.Bundle;
    import android.os.IBinder;
    import android.provider.Settings;
    import android.util.Log;
    import android.widget.Toast;

    public class GPSTracker extends Service implements LocationListener {
        private final Context mContext;

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS status
    boolean canGetLocation = false;

    Location location; // location
    double latitude; // latitude
    double longitude; // longitude

    // The minimum distance to change Updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

    // Declaring a Location Manager
    protected LocationManager locationManager;

    public GPSTracker(Context context) {
        this.mContext = context;
        getLocation();
    }

    public Location getLocation() {
        try {

            locationManager = (LocationManager) mContext
                    .getSystemService(LOCATION_SERVICE);

            // getting GPS status
            isGPSEnabled = locationManager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);

            // getting network status
            isNetworkEnabled = locationManager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            if (!isGPSEnabled && !isNetworkEnabled) {
                Toast.makeText(getApplicationContext(), "NO PROVIDER ENABLED",
                        Toast.LENGTH_LONG).show();
            } else {
                this.canGetLocation = true;
                // First get location from Network Provider
                if (isNetworkEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER, 0, 0, this);
                    Log.d("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER, 0, 0, this);
                        Log.d("GPS Enabled", "GPS Enabled");
                        if (locationManager != null) {
                            location = locationManager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return location;
    }

    /**
     * Stop using GPS listener Calling this function will stop using GPS in your
     * app
     * */
    public void stopUsingGPS() {
        if (locationManager != null) {
            locationManager.removeUpdates(GPSTracker.this);
        }
    }

    /**
     * Function to get latitude
     * */
    public double getLatitude() {
        if (location != null) {
            latitude = location.getLatitude();
        }

        // return latitude
        return latitude;
    }

    /**
     * Function to get longitude
     * */
    public double getLongitude() {
        if (location != null) {
            longitude = location.getLongitude();
        }

        // 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 is 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) {
        // TODO Auto-generated method stub
        latitude = location.getLatitude();
        longitude = location.getLongitude();
        Log.i("location==", "" + "location change");

    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub
        Log.i("location==", "" + "on provieder disabale");

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub
        Log.i("location==", "" + "on provieder enable");

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub
        Log.i("location==", "" + "onstatus change ");

    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub

        return null;
    }
}

Android应用未收到位置更新

2 个答案: