在android的谷歌地图中没有得到经纬度的值

Question

我正在使用谷歌地图。并且在 displayMap() 方法中 system.out.println 中显示当前位置，但经纬度显示为 0.0。我的问题是为什么不显示当前的经纬度？

我把我的代码发给你。请检查我的代码并建议我如何获取当前纬度和当前经度的值？ 按钮 btnSubmit = null;

/** Use for Google Map */


private GoogleMap googleMap = null;
    private SupportMapFragment supportMapFragment = null;
    public double latitude=0, longitude=0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.splash_screen);
        btnSubmit = (Button) findViewById(R.id.btnSubmit);
        btnSubmit.setOnClickListener(this);

        try {
            // Loading map
            initializeMap();

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

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    /** Default Map is Initialize */
    @SuppressLint("NewApi")
    private void initializeMap() {
        if (googleMap == null) {
            // googleMap = ((MapFragment) getFragmentManager().findFragmentById(
            // R.id.map)).getMap();

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

            if (googleMap != null) {
                displayMap();
            }
        }
    }

    /** Display The Current Location on Map */
    private void displayMap() {
        // Enable MyLocation Layer of Google Map
                googleMap.setMyLocationEnabled(true);

                // Get LocationManager object from System Service LOCATION_SERVICE
                LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

                // Create a criteria Object to retrieve provider
                Criteria criteria = new Criteria();

                // Get the name of best provider
                String provider = locationManager.getBestProvider(criteria, true);

                // Get Current Location
                Location myLocation = locationManager.getLastKnownLocation(provider);

                // set Map Type
                googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

                // Get latitude of Current Location
                latitude = myLocation.getLatitude();
                System.out.println("latitude====="+latitude);

                // Get longitude of Current Location
                longitude = myLocation.getLongitude();
                System.out.println("longitude====="+longitude);
                // Create a LatLng object for the current location
                LatLng latLng = new LatLng(latitude, longitude);

                // Show the current location in Google Map
                googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

                // Zoom in Google map
                googleMap.animateCamera(CameraUpdateFactory.zoomTo(20));
                googleMap.addMarker(new MarkerOptions().position(
                        new LatLng(latitude, longitude)).title("You R Here..."));

    }

    @Override
    protected void onResume() {
        super.onResume();
        initializeMap();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
        case R.id.btnSubmit:
            Intent intent = new Intent(getBaseContext(), RegisterActivity.class);
            intent.putExtra("latitude", latitude);
            intent.putExtra("longitude", longitude);
            startActivity(intent);
            break;

        default:
            break;
        }
    }

}

我的xml文件是，

 <fragment
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

Answer 1

创建单独的服务类并使用 LocationListener 实现它：

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;

    boolean canGetLocation = false;

    Location location; 
    double latitude;
    double longitude;

    //The minimum distance to change updates in metters 
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; //10 metters

    //The minimum time beetwen 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)
            { 
                // no network provider is enabled 
            } 
            else 
            { 
                this.canGetLocation = true;

                //First get location from Network Provider 
                if (isNetworkEnabled)
                { 
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    Log.d("Network", "Network");

                    if (locationManager != null)
                    { 
                        location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        updateGPSCoordinates(); 
                    } 
                } 

                //if GPS Enabled get lat/long using GPS Services 
                if (isGPSEnabled)
                { 
                    if (location == null) 
                    { 
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                        Log.d("GPS Enabled", "GPS Enabled");

                        if (locationManager != null)
                        { 
                            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            updateGPSCoordinates(); 
                        } 
                    } 
                } 
            } 
        } 
        catch (Exception e)
        { 
            //e.printStackTrace(); 
            Log.e("Error : Location", "Impossible to connect to LocationManager", e);
        } 

        return location; 
    } 

    public void updateGPSCoordinates() 
    { 
        if (location != null) 
        { 
            latitude = location.getLatitude();
            longitude = location.getLongitude();
        } 
    } 

    /** 
     * 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;
    } 

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

        return longitude;
    } 

    /** 
     * Function to check GPS/wifi enabled 
     */ 
    public boolean canGetLocation() 
    { 
        return this.canGetLocation;
    } 

//    /** 
//     * Function to show settings alert dialog 
//     */ 
//    public void showSettingsAlert() 
//    { 
//        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// 
//        //Setting Dialog Title 
//        alertDialog.setTitle(R.string.GPSAlertDialogTitle);
// 
//        //Setting Dialog Message 
//        alertDialog.setMessage(R.string.GPSAlertDialogMessage);
// 
//        //On Pressing Setting button 
//        alertDialog.setPositiveButton(R.string.settings, new DialogInterface.OnClickListener() 
//        {    
//            @Override 
//            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(R.string.cancel, new DialogInterface.OnClickListener() 
//        {    
//            @Override 
//            public void onClick(DialogInterface dialog, int which) 
//            { 
//                dialog.cancel();
//            } 
//        }); 
// 
//        alertDialog.show();
//    } 

    /** 
     * Get list of address by latitude and longitude 
     * @return null or List<Address> 
     */ 
    public List<Address> getGeocoderAddress(Context context)
    { 
        if (location != null) 
        { 
            Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
            try  
            { 
                List<Address> addresses = geocoder.getFromLocation(latitude, longitude, 1);
                return addresses;
            }  
            catch (IOException e) 
            { 
                //e.printStackTrace(); 
                Log.e("Error : Geocoder", "Impossible to connect to Geocoder", e);
            } 
        } 

        return null; 
    } 

    /** 
     * Try to get AddressLine 
     * @return null or addressLine 
     */ 
    public String getAddressLine(Context context)
    { 
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        { 
            Address address = addresses.get(0);
            String addressLine = address.getAddressLine(0);

            return addressLine;
        } 
        else 
        { 
            return null; 
        } 
    } 

    /** 
     * Try to get Locality 
     * @return null or locality 
     */ 
    public String getLocality(Context context)
    { 
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        { 
            Address address = addresses.get(0);
            String locality = address.getLocality();

            return locality;
        } 
        else 
        { 
            return null; 
        } 
    } 

    /** 
     * Try to get Postal Code 
     * @return null or postalCode 
     */ 
    public String getPostalCode(Context context)
    { 
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        { 
            Address address = addresses.get(0);
            String postalCode = address.getPostalCode();

            return postalCode;
        } 
        else 
        { 
            return null; 
        } 
    } 

    /** 
     * Try to get CountryName 
     * @return null or postalCode 
     */ 
    public String getCountryName(Context context)
    { 
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        { 
            Address address = addresses.get(0);
            String countryName = address.getCountryName();

            return countryName;
        } 
        else 
        { 
            return null; 
        } 
    } 

    @Override 
    public void onLocationChanged(Location location)  
    {    
    } 

    @Override 
    public void onProviderDisabled(String provider) 
    {    
    } 

    @Override 
    public void onProviderEnabled(String provider) 
    {    
    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) 
    {    
    } 

    @Override 
    public IBinder onBind(Intent intent) 
    { 
        return null; 
    } 
}  

现在可以轻松获取经纬度

GPSTracker gpsTracker = new GPSTracker(mContext);
latitude = gpsTracker.getLatitude();
longitude = gpsTracker.getLongitude();

不要忘记在清单文件中添加权限。 干杯