我正在尝试构建一个使用 GoogleClientApi 和 LocationServices 请求当前位置的应用程序，但即使我启用了 WiFi、移动数据和 GPS，位置始终为 null，并在多个设备上进行了相同的测试

来自 manifest.xml 的权限:

<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

Activity :

public class FindStation extends Fragment implements GoogleApiClient.ConnectionCallbacks,GoogleApiClient.OnConnectionFailedListener,com.google.android.gms.location.LocationListener
{

    public static FragmentManager fragmentManager;
    Button goButton;
    Spinner spinner;
    SupportMapFragment mapFragment;
    GoogleMap map;
    List<Stations> stationsList;
    ArrayList<String> stationsAddresses;

    private static View view;
    ArrayList<MarkerOptions> markers;
    GoogleApiClient mGoogleApiClient;
    LocationServices locationServices;
    Location location;
    private static String TAG="FIND_STATION";

    Context context;
    LocationRequest mLocationRequest;
    LocationListener locationListener;
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        context= getActivity();
        locationListener=this;
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(10000);
        mLocationRequest.setFastestInterval(5000);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest.setSmallestDisplacement(10);
        /*mGoogleApiClient = new GoogleApiClient.Builder(getActivity())
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();*/

        buildGoogleApiClient();




        if (view != null) {
            ViewGroup parent = (ViewGroup) view.getParent();
            if (parent != null)
                parent.removeView(view);
        }
        try {
            view = inflater.inflate(R.layout.activity_find_station, container, false);
        } catch (InflateException e) {

        }

              inflater.inflate(R.layout.activity_find_station,container,false);
        stationsAddresses = new ArrayList<>();
        goButton= (Button) view.findViewById(R.id.button);
        //goButton.setVisibility(View.INVISIBLE);
        spinner= (Spinner) view.findViewById(R.id.spinner);
        stationsList = Stations.listAll(Stations.class);
        markers = new ArrayList<>();
        for (int i = 0; i <stationsList.size() ; i++) {
            stationsAddresses.add(stationsList.get(i).getStationLocation());
            markers.add(new MarkerOptions().position(new LatLng(stationsList.get(i).getStationLat(), stationsList.get(i).getStationLong())).title(stationsList.get(i).getStationName()));
        }
        goButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //location= LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);



            }
        });


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


        try {
           // map.setMyLocationEnabled(true);
        } catch (Exception e) {
            e.printStackTrace();
        }

        /*thread = new Thread(new MyThread());
        thread.start();*/
        return view;
    }

    private void initialize() {
        if (map==null) {
            Fragment fragment= getChildFragmentManager().findFragmentById(R.id.map);
            mapFragment= (SupportMapFragment) fragment;
            map=mapFragment.getMap();
            for (int i = 0; i <markers.size() ; i++) {
              map.addMarker(markers.get(i));
            }
            // check if map is created successfully or not
            if (map==null) {
                Toast.makeText(super.getActivity(),
                        "Sorry! unable to create maps", Toast.LENGTH_SHORT)
                        .show();
            }
        }


    }

    public void onDestroyView() {
        super.onDestroyView();


        android.support.v4.app.FragmentManager fm = getActivity().getSupportFragmentManager();
        SupportMapFragment fragment = (SupportMapFragment) fm.findFragmentById(R.id.map);

        if (fragment!=null) {
                android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();
                ft.remove(fragment);
                ft.commit();

        }

    }

    @Override
    public void onConnected(Bundle bundle) {
        location= LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (location!=null){
            Log.d(TAG,location.toString());
        CameraUpdate update = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(),location.getLongitude()),3f);
        map.animateCamera(update);
        }
        Log.d(TAG,"connected");

    }

    @Override
    public void onConnectionSuspended(int i) {
        Log.d(TAG,"connection suspended "+String.valueOf(i));
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.d(TAG,"connection failed");
    }


    @Override
    public void onLocationChanged(Location location) {`enter code here`
        Log.d(TAG,location.toString());
        this.location=location;
        if (location!=null) {
            CameraUpdate update = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 3f);
            map.animateCamera(update);
            Log.d(TAG, "camera updated to new position");
            goButton.setVisibility(View.VISIBLE);
        }
    }



    @Override
    public void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
        Log.d(TAG,"connect() was called");
    }
    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(context)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

}

奇怪的是调用了 onConnect() 方法，但之后 Location 始终为 null 并且永远不会调用 onLocationChanged()

使用 map ，我尝试启用我的位置，当你点击右上角的按钮时它会工作，它会返回位置并为相机设置动画。

更新 1

更新了 onConnected() 方法并使其请求位置更新，

public void onConnected(Bundle bundle) {
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, locationListener);

    if (location!=null){
        Log.d(TAG,location.toString());
    CameraUpdate update = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(),location.getLongitude()),3f);
    map.animateCamera(update);
    }
    Log.d(TAG,"connected");}

然后我用一个按钮调用 lastKnownLocation()，因为 onLocationChanged() 仍然没有被调用，而且返回的 Location 仍然是 null

更新 2:

完全相同的代码在 Android 5.0.1 上运行并且运行完美 所有其他设备都在 android 2.3.7,4.0.1 上，它们都没有工作，

知道关于位置的 Android API 有何不同吗？

最佳答案

您需要调用 requestLocationUpdates() 以注册监听器并调用 onLocationChanged()。

请务必尽快取消注册监听器，以免电池耗尽。

另请注意，getLastLocation() 方法可以并且将会返回 null。主要问题是它不会提示操作系统请求新的位置锁定，而只是检查是否有来自其他应用程序位置请求的最后一个已知位置。如果最近没有其他应用发出位置请求，则会向您返回一个空位置。

保证您实际获得位置的唯一方法是请求一个位置，这是通过调用 requestLocationUpdates() 完成的。

这里有一个工作示例供引用:

public class MainActivity extends FragmentActivity
        implements OnMapReadyCallback,
        GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,
        LocationListener {

    private GoogleMap map;
    private LocationRequest mLocationRequest;
    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;
    private Marker marker;

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

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

        buildGoogleApiClient();
        mGoogleApiClient.connect();

        if (map == null) {
            SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                    .findFragmentById(R.id.map);

            mapFragment.getMapAsync(this);
        }
    }

    @Override
    public void onMapReady(GoogleMap retMap) {

        map = retMap;

        setUpMap();

    }

    public void setUpMap(){

        map.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        map.setMyLocationEnabled(true);
    }

    @Override
    protected void onPause(){
        super.onPause();
        if (mGoogleApiClient != null) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
        }
    }

    protected synchronized void buildGoogleApiClient() {
        Toast.makeText(this, "buildGoogleApiClient", Toast.LENGTH_SHORT).show();
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

    @Override
    public void onConnected(Bundle bundle) {
        Toast.makeText(this,"onConnected",Toast.LENGTH_SHORT).show();

        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(1000);
        mLocationRequest.setFastestInterval(1000);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);

        //mLocationRequest.setSmallestDisplacement(0.1F);

        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
    }

    @Override
    public void onConnectionSuspended(int i) {
        Toast.makeText(this,"onConnectionSuspended",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Toast.makeText(this,"onConnectionFailed",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onLocationChanged(Location location) {
        mLastLocation = location;

        //remove previous current location Marker
        if (marker != null){
            marker.remove();
        }

        double dLatitude = mLastLocation.getLatitude();
        double dLongitude = mLastLocation.getLongitude();
        marker = map.addMarker(new MarkerOptions().position(new LatLng(dLatitude, dLongitude))
                .title("My Location").icon(BitmapDescriptorFactory
                        .defaultMarker(BitmapDescriptorFactory.HUE_RED)));
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(dLatitude, dLongitude), 8));

    }

}

还有一点，如果您的 map 位于 fragment 中，则无需嵌套 SupportMapFragment。您可以只让 Fragment 扩展 SupportMapFragment。这消除了嵌套 Fragment 的需要，您甚至不需要扩充任何布局 xml，这是一个简单的示例:

public class MapTabFragment extends SupportMapFragment 
                                    implements OnMapReadyCallback {

    private GoogleMap mMap;
    private Marker marker;


    public MapTabFragment() {
    }

    @Override
    public void onResume() {
        super.onResume();

        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {

        if (mMap == null) {

            getMapAsync(this);
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {

        mMap = googleMap;
        setUpMap();
    }

    private void setUpMap() {

        mMap.setMyLocationEnabled(true);
        mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        mMap.getUiSettings().setMapToolbarEnabled(false);


        mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {

            @Override
            public void onMapClick(LatLng point) {

                //remove previously placed Marker
                if (marker != null) {
                    marker.remove();
                }

                //place marker where user just clicked
                marker = mMap.addMarker(new MarkerOptions().position(point).title("Marker")
                        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA)));

            }
        });

    }
}

关于android - GoogleApiClient 中的 getLastLocation() 始终为 null，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32567839/