java - 使用 LocationServices 获取纬度和经度

Question

我正在尝试使用以下代码获取我的 Android 应用程序的纬度和经度。

public class MainActivity extends AppCompatActivity {
    private FusedLocationProviderClient client;
    private double latitude;
    private double longitude;
    private String test;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestPermission();
        client = LocationServices.getFusedLocationProviderClient(this);
        client.getLastLocation().addOnSuccessListener(this, new OnSuccessListener<Location>() {
            @Override
            public void onSuccess(Location location) {
                if (location != null) {
                    latitude = location.getLatitude();
                    longitude = location.getLongitude();
                    test = location.toString();
                }
            }
        });
        setContentView(R.layout.activity_main);
    }

    private void requestPermission(){
        ActivityCompat.requestPermissions(this,new String[]{ACCESS_FINE_LOCATION},1);
        ActivityCompat.requestPermissions(this,new String[]{ACCESS_COARSE_LOCATION},1);
    }
}

但是 onSuccess 方法中的位置始终为空，我不明白为什么。我的 list 文件具有以下权限:

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

Answer 1

尝试使用此代码来获取当前位置。

public class MapActivity extends AppCompatActivity implements OnMapReadyCallback,
    GoogleApiClient.OnConnectionFailedListener{

@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

}

@Override
public void onMapReady(GoogleMap googleMap) {
    Toast.makeText(this, "Map is Ready", Toast.LENGTH_SHORT).show();
    Log.d(TAG, "onMapReady: map is ready");
    mMap = googleMap;

    if (mLocationPermissionsGranted) {
        getDeviceLocation();

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        mMap.setMyLocationEnabled(true);
        mMap.getUiSettings().setMyLocationButtonEnabled(false);
    }
}

private static final String TAG = "MapActivity";

private static final String FINE_LOCATION = Manifest.permission.ACCESS_FINE_LOCATION;
private static final String COURSE_LOCATION = Manifest.permission.ACCESS_COARSE_LOCATION;
private static final int LOCATION_PERMISSION_REQUEST_CODE = 1234;
private static final float DEFAULT_ZOOM = 15f;
private static final int PLACE_PICKER_REQUEST = 1;

//vars
private Boolean mLocationPermissionsGranted = false;
private GoogleMap mMap;
private FusedLocationProviderClient mFusedLocationProviderClient;
private Marker mMarker;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);

    getLocationPermission();

}

private void getDeviceLocation(){
    Log.d(TAG, "getDeviceLocation: getting the devices current location");

    mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);

    try{
        if(mLocationPermissionsGranted){

            final Task location = mFusedLocationProviderClient.getLastLocation();
            location.addOnCompleteListener(new OnCompleteListener() {
                @Override
                public void onComplete(@NonNull Task task) {
                    if(task.isSuccessful()){
                        Log.d(TAG, "onComplete: found location!");
                        Location currentLocation = (Location) task.getResult();

                        moveCamera(new LatLng(currentLocation.getLatitude(), currentLocation.getLongitude()),
                                DEFAULT_ZOOM,
                                "My Location");

                    }else{
                        Log.d(TAG, "onComplete: current location is null");
                        Toast.makeText(MapActivity.this, "unable to get current location", Toast.LENGTH_SHORT).show();
                    }
                }
            });
        }
    }catch (SecurityException e){
        Log.e(TAG, "getDeviceLocation: SecurityException: " + e.getMessage() );
    }
}



private void initMap(){
    Log.d(TAG, "initMap: initializing map");
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

    mapFragment.getMapAsync(MapActivity.this);
}

private void getLocationPermission(){
    Log.d(TAG, "getLocationPermission: getting location permissions");
    String[] permissions = {Manifest.permission.ACCESS_FINE_LOCATION,
    Manifest.permission.ACCESS_COARSE_LOCATION};

    if(ContextCompat.checkSelfPermission(this.getApplicationContext(),
            FINE_LOCATION) == PackageManager.PERMISSION_GRANTED){
        if(ContextCompat.checkSelfPermission(this.getApplicationContext(),
                COURSE_LOCATION) == PackageManager.PERMISSION_GRANTED){
            mLocationPermissionsGranted = true;
            initMap();
        }else{
            ActivityCompat.requestPermissions(this,
                    permissions,
                    LOCATION_PERMISSION_REQUEST_CODE);
        }
    }else{
        ActivityCompat.requestPermissions(this,
                permissions,
                LOCATION_PERMISSION_REQUEST_CODE);
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    Log.d(TAG, "onRequestPermissionsResult: called.");
    mLocationPermissionsGranted = false;

    switch(requestCode){
        case LOCATION_PERMISSION_REQUEST_CODE:{
            if(grantResults.length > 0){
                for(int i = 0; i < grantResults.length; i++){
                    if(grantResults[i] != PackageManager.PERMISSION_GRANTED){
                        mLocationPermissionsGranted = false;
                        Log.d(TAG, "onRequestPermissionsResult: permission failed");
                        return;
                    }
                }
                Log.d(TAG, "onRequestPermissionsResult: permission granted");
                mLocationPermissionsGranted = true;
                //initialize our map
                initMap();
            }
        }
    }
}
 }