Android google map api getlastlocation（）總是返回null

Question

我確實需要持續獲取用戶位置;因此，我使用getlastlocation（）來獲取用戶的當前位置。但是，它總是返回null。

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

    private GoogleMap mMap; 
    private GoogleApiClient mGoogleApiClient; 
    Location mLastLocation; 
    protected double x, y; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_maps); 
    // Obtain the SupportMapFragment and get notified when the map is ready to be used. 
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
      .findFragmentById(R.id.map); 
    mapFragment.getMapAsync(this); 

    if(mGoogleApiClient == null){ 
     mGoogleApiClient = new GoogleApiClient.Builder(this) 
       .addConnectionCallbacks(this) 
       .addOnConnectionFailedListener(this) 
       .addApi(LocationServices.API) 
       .build(); 
    } 
} 

protected void onStart(){ 
    mGoogleApiClient.connect(); 
    super.onStart(); 
} 

protected void onStop() { 

    if(mGoogleApiClient != null) { 
     mGoogleApiClient.disconnect(); 
    } 
    super.onStop(); 
} 

@Override 
public void onConnected(Bundle bundle){ 
    if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) 
      != PackageManager.PERMISSION_GRANTED){ 
     ActivityCompat.requestPermissions(this, 
       new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1); 
    } 
    else { 
     mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient); 
     if(mLastLocation != null){ 
      x = mLastLocation.getLatitude(); 
      y = mLastLocation.getLongitude(); 
     } 
     else{ 
      Log.e("error", "null"); 
     } 
    } 
} 

@Override 
public void onConnectionSuspended(int i) { 

} 

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

} 

@Override 
public void onMapReady(GoogleMap googleMap) { 
    mMap = googleMap; 

    LatLng gpsLocation = new LatLng(x, y); 
    mMap.addMarker(new MarkerOptions().position(gpsLocation).title("Here")); 
    mMap.moveCamera(CameraUpdateFactory.newLatLng(gpsLocation)); 
} 

Log.e("error", "null")總是執行，這意味着getlastlocation（）始終返回null。在AndroidManifest，我有足夠的國家批准

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

我搜索了在計算器上類似的帖子，他們給某些原因（例如：GPS不開放），但沒有人可以在我的情況下適用。

Answer 1

你是否創造了LocationRequest並要求使用requestLocationUpdates進行位置更新？

您需要創建LocationRequest像下面的代碼。

LocationRequest mLocationRequest; 

protected void createLocationRequest() { 

     mLocationRequest = new LocationRequest(); 
     mLocationRequest.setInterval(10000); 
     mLocationRequest.setFastestInterval(5000); 
     mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY); 

} 

而且使用LocationRequest，你需要調用的FusedLocationApirequestLocationUpdates像下面的代碼。

protected void startLocationUpdates(){ 
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, 
      mLocationRequest,this); 
} 

之後，你將在FusedLocationApigetlastlocation()方法得到的位置。

另外你應該打電話removeLocationUpdates，當它不是必需的。

protected void stopLocationUpdates() { 
    LocationServices.FusedLocationApi.removeLocationUpdates(
      mGoogleApiClient, this); 
}