如何在 Map 片段中调用活动方法或整个活动

Question

几天前，我开始了我的第一次编码体验。 没有找到我的问题的答案，所以我希望有人能帮助我。

在我的项目中，我有一个MainActivity和一个使用Fragments的BottomNavigationView 。 我添加了一个 map 作为片段之一，它工作正常。 但是我在MapsActivity中更改并添加了一些方法，例如设备位置和请求许可。 但是当我运行应用程序时它不会调用这些方法，所以我认为这是因为MapFragment需要获取MapsActivity的方法，但我不知道如何解决问题，也没有为我找到答案问题。

我的地图片段

public class Map_Fragment extends Fragment implements OnMapReadyCallback {

    SupportMapFragment mapFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_map_, container, false);
        mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
        if (mapFragment == null) {
            FragmentManager fm = getFragmentManager();
            FragmentTransaction ft = fm.beginTransaction();
            mapFragment = SupportMapFragment.newInstance();
            ft.replace(R.id.map, mapFragment).commit();

        }

        mapFragment.getMapAsync(this);
        
        // Inflate the layout for this fragment
        return v;
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {


    }
}

我的地图活动：

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private static final String TAG = "MapActivity";
    private GoogleMap mMap;
    private static final String FINE_LOCATION = Manifest.permission.ACCESS_FINE_LOCATION;
    private static final String COARSE_LOCATION = Manifest.permission.ACCESS_COARSE_LOCATION;
    private static final int LOCATION_PERMISSION_REQUEST_CODE = 1234;
    private static final float DEFAULT_ZOOM = 150f;
    // vars
    private Boolean mLocationPermissionGranted = false;

    private FusedLocationProviderClient mFusedLocationProviderClient;


    protected void createLocationRequest() {
        LocationRequest locationRequest = LocationRequest.create();
        locationRequest.setInterval(10000);
        locationRequest.setFastestInterval(5000);
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }
    
    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        Log.d(TAG, "onMapReady: Map is ready");

        if (mLocationPermissionGranted) {
            getDeviceLocation();
        }
    }
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        Log.d(TAG, "onCreate: Map started");

        getLocationPermission();


    }

    private void getDeviceLocation() {
        Log.d(TAG, "getDeviceLocation : get the Devices current location");

        mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);

        try {
            if (mLocationPermissionGranted) {
                Task location = mFusedLocationProviderClient.getLastLocation();
                location.addOnCompleteListener(new OnCompleteListener() {
                    @Override
                    public void onComplete(@NonNull Task task) {
                        if (task.isSuccessful()) {
                            Log.d(TAG, "onComplete: found location");
                            Location currentlocation = (Location) task.getResult();

                            moveCamera(new LatLng(currentlocation.getLatitude(), currentlocation.getLongitude()), DEFAULT_ZOOM);
                        } else {
                            Log.d(TAG, "onComplete: current Location is null");
                            Toast.makeText(MapsActivity.this, "unable to find location", Toast.LENGTH_SHORT);
                        }

                    }
                });
            }
        } catch (SecurityException e) {
            Log.e(TAG, "getDeviceLocation: SecurityException: " + e.getMessage());
        }

    }

    private void moveCamera(LatLng latLng, float zoom) {
        Log.d(TAG, "moveCamera: move the Camera to lat: " + latLng.latitude + ", lng" + latLng.longitude);
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, zoom));
    }

    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    private void initMap() {
        Log.d(TAG, "Init Map");
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap googleMap) {
                mMap = googleMap;


            }
        });
    }

    private void getLocationPermission() {
        Log.d(TAG, "getLocationPermission");
        String[] permissions = {Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION};

        if (ContextCompat.checkSelfPermission(this.getApplicationContext(), FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
            if (ContextCompat.checkSelfPermission(this.getApplicationContext(), COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
                mLocationPermissionGranted = true;
                initMap();
            } else {

                ActivityCompat.requestPermissions(this, permissions, LOCATION_PERMISSION_REQUEST_CODE);
            }

        } else {
            ActivityCompat.requestPermissions(this, permissions, LOCATION_PERMISSION_REQUEST_CODE);
        }

    }

    public void onRequestPermissionResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grandResults) {
        Log.d(TAG, " onRequestPermissionResult: called");
        mLocationPermissionGranted = false;

        switch (requestCode) {
            case LOCATION_PERMISSION_REQUEST_CODE: {
                if (grandResults.length > 0) {
                    for (int i = 0; i < grandResults.length; i++) {
                        if (grandResults[i] == PackageManager.PERMISSION_GRANTED) {
                            mLocationPermissionGranted = false;
                            Log.d(TAG, "onRequestPermissionResult: failed");
                            return;
                        }
                    }
                    Log.d(TAG, "onRequestPermissionResult: Permission granted");
                    mLocationPermissionGranted = true;
                    //initialize our Map
                    initMap();
                }
            }
        }
    }


    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
}

MapFragment 使用 MapActivity 的方法如何将这两者相互连接？

Answer 1

如果我正确理解您的问题，您希望从活动而不是片段运行OnMapReadyCallback相关方法。 如果是这种情况，您应该像这样修复您的片段：

public class Map_Fragment extends Fragment {

    SupportMapFragment mapFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                     Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.fragment_map_,container, false);
        mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
        if (mapFragment==null){
            FragmentManager fm = getFragmentManager();
            FragmentTransaction ft = fm.beginTransaction();
            mapFragment=SupportMapFragment.newInstance();
            ft.replace(R.id.map, mapFragment).commit();
        }

        Activity activity = getActivity();
        if (activity != null && activity instanceof MainActivity) {
            mapFragment.getMapAsync((MainActivity) activity);
        }

        // Inflate the layout for this fragment
        return v;
    }
}