在Fragment上获取当前设备位置

Question

我想获取当前（或最后一个已知的）设备位置，并在应用启动时将相机移至地图上的位置。我已经尝试了很多方法，但是在Fragment上没有任何效果。 这是我当前与应用程序立即关闭的代码。

MapFragment.java

public class MapFragment extends Fragment implements OnMapReadyCallback
{

private GoogleMap mGoogleMap;
private FusedLocationProviderClient mFusedLocationProviderClient;
private static final int PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION = 1;
private boolean mLocationPermissionGranted;
private Location mLastKnownLocation;
private final LatLng mDefaultLocation = new LatLng(-33.8523341, 151.2106085);
private static final int DEFAULT_ZOOM = 15;

public MapFragment() {
    // Required empty public constructor
}

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

    mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this.getActivity());
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View mView = inflater.inflate(R.layout.fragment_map, container, false);

    return mView;
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}

@Override
public void onMapReady(GoogleMap googleMap) {

    MapsInitializer.initialize(getContext());

    mGoogleMap = googleMap;
    mGoogleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    // Turn on the My Location layer and the related control on the map.
    updateLocationUI();

    // Get the current location of the device and set the position of the map.
    getDeviceLocation();
}

private void getLocationPermission() {
    /*
     * Request location permission, so that we can get the location of the
     * device. The result of the permission request is handled by a callback,
     * onRequestPermissionsResult.
     */
    if (ContextCompat.checkSelfPermission(this.getActivity(),
            android.Manifest.permission.ACCESS_FINE_LOCATION)
            == PackageManager.PERMISSION_GRANTED) {
        mLocationPermissionGranted = true;
    } else {
        ActivityCompat.requestPermissions(this.getActivity(),
                new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
                PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
    mLocationPermissionGranted = false;
    switch (requestCode) {
        case PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                mLocationPermissionGranted = true;
            }
        }
    }
    updateLocationUI();
}

private void updateLocationUI() {
    if (mGoogleMap == null) {
        return;
    }
    try {
        if (mLocationPermissionGranted) {
            mGoogleMap.setMyLocationEnabled(true);
            mGoogleMap.getUiSettings().setMyLocationButtonEnabled(true);
        } else {
            mGoogleMap.setMyLocationEnabled(false);
            mGoogleMap.getUiSettings().setMyLocationButtonEnabled(false);
            mLastKnownLocation = null;
            getLocationPermission();
        }
    } catch (SecurityException e)  {
        Log.e("Exception: %s", e.getMessage());
    }
}

private void getDeviceLocation() {
    /*
     * Get the best and most recent location of the device, which may be null in rare
     * cases when a location is not available.
     */
    try {
        if (mLocationPermissionGranted) {
            Task locationResult = mFusedLocationProviderClient.getLastLocation();
            locationResult.addOnCompleteListener((Executor) this, new OnCompleteListener() {
                @Override
                public void onComplete(@NonNull Task task) {
                    if (task.isSuccessful()) {
                        // Set the map's camera position to the current location of the device.
                        mLastKnownLocation = (Location) task.getResult();
                        mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
                                new LatLng(mLastKnownLocation.getLatitude(),
                                        mLastKnownLocation.getLongitude()), DEFAULT_ZOOM));
                    } else {
                        Log.d(TAG, "Current location is null. Using defaults.");
                        Log.e(TAG, "Exception: %s", task.getException());
                        mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(mDefaultLocation, DEFAULT_ZOOM));
                        mGoogleMap.getUiSettings().setMyLocationButtonEnabled(false);
                    }
                }
            });
        }
    } catch(SecurityException e)  {
        Log.e("Exception: %s", e.getMessage());
    }
}

这种方式适用于FragmentActivity，但不适用于Fragment。 我还在 AndroindManifest.xml 中授予了ACCESS_FINE_LOCATION权限。