FusedLocationClient 为一些用户返回空值

Question

在我的 Android 应用中，我目前正在使用 Fused Location Provider api（参见下面的代码）来获取我的用户的位置，并且我很少抱怨我的应用无法在应用中获取他们自己的位置。

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

    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

    if ( ContextCompat.checkSelfPermission( this, android.Manifest.permission.ACCESS_FINE_LOCATION ) == PackageManager.PERMISSION_GRANTED ) {
        mLocationCallback = new LocationCallback() {
            @Override
            public void onLocationResult(LocationResult locationResult) {
                if (locationResult == null) {
                    return;
                }
                if(locationResult.getLastLocation() != null)
                    currentLocation = locationResult.getLastLocation();
            }
        };
        mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback,null);
        locationOn = true;
    }

经过一些检查，它似乎有时会在一段时间（或永远）内不断返回空值，而我的应用程序将无法运行。其他 GPS 应用程序也能正常工作（例如 Google 地图）。

我的实现是正确的，还是像 Google Play Services 这样的外部设备被置于省电模式？

Answer 1

您所做的是正确的，但位置提供程序有时会返回 null。您可能必须妥善处理它。如果您想手动获取位置，请使用LocationManager。

在我的代码中尝试这个 sn-p（这样我永远不会在我想要的位置获得空值，因为它至少会返回最后一个位置或正确地向用户显示错误消息以及如何解决它。：

private void updateLocations(){

 String str_latitude = "";

 String str_longitude = "";

 String provider = "";

    locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {

        provider = LocationManager.GPS_PROVIDER;

    } else if (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {

        provider = LocationManager.NETWORK_PROVIDER;
    }

    if (!provider.equals("")) {

        mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(MainActivity.this);

        @SuppressLint("MissingPermission") Task locationResult = mFusedLocationProviderClient.getLastLocation();

        locationResult.addOnCompleteListener(MainActivity.this, new OnCompleteListener() {

            @Override
            public void onComplete(@NonNull Task task) {
                if (task.isSuccessful()) {

                   Location mLastKnownLocation = (Location) task.getResult();

                    if (mLastKnownLocation != null) {

                        str_longitude = String.valueOf(mLastKnownLocation.getLatitude());

                        str_latitude = String.valueOf(mLastKnownLocation.getLongitude());

                        Toast.makeText(context, "Lat: "+str_latitude + ", Long " + str_longitude, Toast.LENGTH_LONG).show();
                    }

                    if (str_latitude.equals("") || str_longitude.equals("")) {

                        Snackbar.make(coordinatorLayout, "Couldn't find location, please try again in a moment", Snackbar.LENGTH_LONG).show();
                    }
                }
            }
        });


    } else if (provider.equals("")) {

        Snackbar snackbar = Snackbar.make(coordinatorLayout, "Seems like all providers of device are disabled", Snackbar.LENGTH_LONG);

        snackbar.setAction("Enable", new View.OnClickListener() {

            @Override
            public void onClick(View v) {
            //Takes user to gps enable settings.
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(intent);
            }
        });

        snackbar.show();
    }

}});