使用 Google Maps API 在 Android 中查找设备当前位置的纬度和经度值

Question

因此基于此提出了许多类似的问题，我也得到了一个可行的解决方案。但是，这似乎只适用于我的物理 Android 设备。如果我将它与模拟器一起使用，该方法会返回一个空值，我不知道为什么。许多消息来源提到我目前使用的代码有更好的替代方案，但他们没有提到具体是什么/如何。这是我用来获取设备当前位置的代码：

@SuppressWarnings("MissingPermission")
    private LatLng getCurrentLocation() {
        LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        String locationProvider = LocationManager.NETWORK_PROVIDER;
        assert locationManager != null;
        android.location.Location lastKnownLocation = locationManager.getLastKnownLocation(locationProvider);
        return new LatLng(lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude());
    }

我也不喜欢必须隐藏警告的事实。我查看的来源包括：

https://developer.android.com/training/location/retrieve-current.html#java

What is the simplest and most robust way to get the user's current location on Android?

第一个不起作用，我得到一个空值。对于我正在寻找的简单结果，第二个看起来过于复杂。

Answer 1

这段代码在我的一个项目中运行良好：

public class LocationManager {
        private static LocationManager requestManager;
        private FusedLocationProviderClient mLocationProviderClient;
        private Location mLocation;
        private Location mMyCurrentLocation;
        private locationSuccessListener mListener;

    public Location getLocation() {
        return mLocation;
    }

    public void setLocation(Location location) {
        mLocation = location;
    }

    private LocationManager(FusedLocationProviderClient fusedLocationProviderClient) {
        this.mLocationProviderClient = fusedLocationProviderClient;
    }

    public static LocationManager createInstance(FusedLocationProviderClient fusedLocationProviderClient) {
        if (requestManager != null) {
            return requestManager;
        } else {
            return requestManager = new LocationManager(fusedLocationProviderClient);
        }
    }

    public static LocationManager getInstance() {
        return requestManager;
    }

    public void setLocation(Activity activity) {
        mListener = (locationSuccessListener) activity;
        LocationCallback callback = new LocationCallback();
        LocationRequest locationRequest = new LocationRequest();
        Task<Void> r = mLocationProviderClient.requestLocationUpdates(locationRequest, callback, Looper.getMainLooper());
        r.addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void aVoid) {
                mLocationProviderClient.getLastLocation().addOnSuccessListener(activity, new OnSuccessListener<Location>() {
                    @Override
                    public void onSuccess(Location location) {
                        mMyCurrentLocation = location;
                        mLocation = location;
                        if (location != null) {
                            mListener.onLocationReceived();
                            mLocationProviderClient.removeLocationUpdates(callback);
                        }
                    }
                });
            }
        });


    }

    public Location getMyCurrentLocation() {
        return mMyCurrentLocation;
    }


    public interface locationSuccessListener {
        void onLocationReceived();
    }

你需要这样做：

public class PlacesActivity extends SingleFragmentActivity implements NavigationView.OnNavigationItemSelectedListener, LocationManager.locationSuccessListener

然后在你的活动中你会得到这个：

@Override
    public void onLocationReceived() {
         Location l = LocationManager.getInstance().getMyCurrentLocation();
             if (l==null){
                 Toast.makeText(this, "unable to get location", Toast.LENGTH_SHORT).show();
                 
             }
    }

要获得许可，您应该这样做：

if (ContextCompat.checkSelfPermission(Objects.requireNonNull(getActivity()), Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(getActivity(),
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    0);