getLastKnownLocation(LocationManager.NETWORK_PROVIDER) retur

Question

我想使用LocationManager API通过网络获取当前位置。

我代码:

locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
boolean isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (isNetworkEnabled) {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 1, this);
    Log.d("Network", "Network Enabled");
    if (locationManager != null) {
        location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        if (location != null) {
            double latitude = location.getLatitude();
            double longitude = location.getLongitude();
        }
    }
}

问题是我得到的经度和纬度都是1.0

Answer 1

Google maps使用用户的lastKnownLocation作为位置，如果lastknownLocation是未知的，则需要时间通过不同的提供商(如GPS或Network)获取位置。我建议使用lastKnownLocation作为基础位置，并使用LocationListener更新它。

       if (ActivityCompat.checkSelfPermission
                (this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
                &&
                ActivityCompat.checkSelfPermission
                        (this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
        {
            requestPermissions(new String[]{
                    Manifest.permission.ACCESS_COARSE_LOCATION,
                    Manifest.permission.ACCESS_FINE_LOCATION
            }, 1);
        }
        else {
            // enable location buttons
            googleMap.setMyLocationEnabled(true);
            googleMap.getUiSettings().setMyLocationButtonEnabled(true);
            // fetch last location if any from provider - GPS.
            final LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
            final Location loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            //if last known location is not available
            if (loc == null) {
                final LocationListener locationListener = new LocationListener() {
                    @Override
                    public void onLocationChanged(final Location location) {
                        // getting location of user
                        final double latitude = location.getLatitude();
                        final double longitude = location.getLongitude();
                        //do something with Lat and Lng
                    }
                    @Override
                    public void onStatusChanged(String provider, int status, Bundle extras) {
                    }
                    @Override
                    public void onProviderEnabled(String provider) {
                        //when user enables the GPS setting, this method is triggered.
                    }
                    @Override
                    public void onProviderDisabled(String provider) {
                        //when no provider is available in this case GPS provider, trigger your gpsDialog here.
                    }
                };
                //update location every 10sec in 500m radius with both provider GPS and Network.
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10*1000, 500, locationListener);
                locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 10000, 500, locationListener);
            }
            else {
                //do something with last known location.
                // getting location of user
                final double latitude = loc.getLatitude();
                final double longitude = loc.getLongitude();
            }
        }

权限处理:

     @Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode) {
        case 1:
            if (grantResults[0] != PackageManager.PERMISSION_GRANTED){
                //do something
            }
        default:
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}