问题
Am trying to build an application that requests the current location using the GoogleClientApi and LocationServices, but the Location is always null even that I enabled the WiFi,Mobile Data and GPS , tested it on several devices all the same
the permissions from the manifest.xml :
<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();
}
}
the strange thing is that the onConnect() method is called but after that the Location is always null and onLocationChanged() is never called
using the maps, i tried the enabling my location and it works when you have the button on the right top corner it returns the location and animates the camera.
UPDATE 1
updated the onConnected() method and made it request locations updates,
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");}
then with a button i call lastKnownLocation() since the onLocationChanged() is not called still, and still the returned Location is null
UPDATE 2 :
The very same code worked on Android 5.0.1 and worked perfectly all the other devices was on android 2.3.7,4.0.1 none of them worked,
Any idea about what difference in the Android APIs regarding the location?
回答1:
You need to call requestLocationUpdates() in order to register the listener and have onLocationChanged() invoked.
Be sure to un-register the listener as soon as possible to avoid excessive battery drain.
Also note that the getLastLocation() method can and will return null. The main problem is that it doesn't prompt a request to the OS for a new location lock, instead it just checks if there was a last known location from some other app's location request. If no other app had recently made a location request, then you get a null location returned to you.
The only way to guarantee that you actually get a location is to request one, and this is done with a call to requestLocationUpdates().
Here is a working example for reference:
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));
}
}
One more thing, if your map is in a Fragment, there is no need to have a nested SupportMapFragment. You can just have your Fragment extend SupportMapFragment. This removes the need of having a nested Fragment, and you don't even need to inflate any layout xml, here is a simple example:
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)));
}
});
}
}
来源：https://stackoverflow.com/questions/32567839/getlastlocation-always-null-in-googleapiclient