LocationListener 和 Fusedlocationproviderclient 都返回空值

Question

我知道这个问题已被多次询问和回答，但没有一个对我有用，我的目标是获取用户当前位置，然后在该位置显示 GoogleMaps 标记，但我完全无法做到这一点，因为 LocationListener和我尝试的 Fusedlocationproviderclient 正在返回 null 值，这里有一些示例代码：

mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0,0,  mLocationListener);

...
private final android.location.LocationListener mLocationListener = new LocationListener() {
    @Override
    public void onLocationChanged(@NonNull Location location) {
        app.l("Fetched");
        currentLocation = location ;
// Null

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

    @Override
    public void onProviderEnabled(String provider) {

    }

    @Override
    public void onProviderDisabled(String provider) {

    }
};

------------另一种方式----

fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
        fetchLocation();

private void fetchLocation() {
    if (ActivityCompat.checkSelfPermission(

                this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_CODE);
        } else {

            LocationRequest mLocationRequest = LocationRequest.create();
            mLocationRequest.setInterval(60000);
            mLocationRequest.setFastestInterval(5000);
            mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

            LocationCallback mLocationCallback = new LocationCallback() {
                @Override
                public void onLocationResult(LocationResult locationResult) {
                    if (locationResult == null) {
                        return;
                    }
                    for (Location location : locationResult.getLocations()) {
                        if (location != null) {
                            app.l("sth1");
                        }
                    }
                }
            };

            LocationServices.getFusedLocationProviderClient(this).requestLocationUpdates(mLocationRequest, mLocationCallback, null);
            LocationServices.getFusedLocationProviderClient(this).getLastLocation().addOnSuccessListener(new OnSuccessListener<Location>() {
                @Override
                public void onSuccess(Location location) {
                    if (location == null){
                        app.l("it's null");
                    }
                }
            });

        }

    }

P.S：我已经提供并检查了所有必需的权限

Answer 1

这是一个简单的解决方案：

LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    ActivityCompat#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for ActivityCompat#requestPermissions for more details.
                return;
            }
            currentLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if (currentLocation == null) {
            }
            if (currentLocation != null) {

                }
    
            }