在android中获取最后一个已知位置[重复]

Question

这个主题是用 SO 填充的，但由于我对 java 的了解有限，我无法获得我的位置。

如果我手动输入纬度和经度，我的代码会按预期工作。我用这个把经纬度硬编码：

class latlang {
    public static double Lat=28.28;
    public static double Lang=84.0;
}

在其他片段中使用，但不仅在地图中： MapFragment.java

public class MapFragment extends Fragment {
    private MapView mMapView;
    private GoogleMap googleMap;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_map, container, false);

        mMapView = rootView.findViewById(R.id.mapView);
        mMapView.onCreate(savedInstanceState);

        mMapView.onResume(); // needed to get the map to display immediately

        try {
            MapsInitializer.initialize(getActivity().getApplicationContext());
        } catch (Exception e) {
            e.printStackTrace();
        }

        mMapView.getMapAsync(mMap -> {
            googleMap = mMap;
            LatLng sydney = new LatLng(latlang.Lat, latlang.Lang);
            googleMap.addMarker(new MarkerOptions().position(sydney).title("Marker Title").snippet("Marker Description"));

            // For zooming automatically to the location of the marker
            CameraPosition cameraPosition = new CameraPosition.Builder().target(sydney).zoom(12).build();
            googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
        });
        return rootView;
    }

    @Override
    public void onResume() {
        super.onResume();
        mMapView.onResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        mMapView.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mMapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mMapView.onLowMemory();
    }
}

请帮助。我完全对FusedLocationProviderClient感到困惑

ma​​in_activity.java

public class MainActivity extends AppCompatActivity {
    private FusedLocationProviderClient mFusedLocationClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
        ViewPager viewPager = findViewById(R.id.view_pager);
        viewPager.setAdapter(sectionsPagerAdapter);
        //new SecondFragment();
        //TabLayout tabs = findViewById(R.id.tabs);
        //tabs.setupWithViewPager(viewPager);
        FloatingActionButton fab = findViewById(R.id.fab);
        FontDrawable drawable = new FontDrawable(this, R.string.fa_plus_solid, true, false);
        drawable.setTextColor(ContextCompat.getColor(this, android.R.color.white));
        fab.setImageDrawable(drawable);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        //Check permission
        if (ContextCompat.checkSelfPermission(getApplicationContext(),
                android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(getApplicationContext(),
                        android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,
                    new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION,
                            android.Manifest.permission.ACCESS_COARSE_LOCATION}, 101);

        }
    }
}

Answer 1

首先你需要像这样初始化fusedLocationClient：

在片段中：

fusedLocationClient = LocationServices.getFusedLocationProviderClient(getContext());

活动中：

fusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

然后检索最后一个已知位置：

fusedLocationClient.getLastLocation()
                .addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
                    @Override
                    public void onSuccess(Location location) {
                        // Got last known location. In some rare situations, this can be null.
                        if (location != null) {
                            // Logic to handle location object            
                            double latitude= location.getLatitude();
                            double longitude= location.getLongitude();
                        } else {
                            //handle null location
                        }
                    }
                });

希望这会有所帮助！