Question

我是android的新手，我已经按照本教程进行了实时资产跟踪。 Tracking Url

现在，我想从Firebase以及应用程序中删除标记，而无需在浏览器中打开Firebase。我该怎么做？有可能吗？

以下代码用于将位置更新发送到Firebase服务器的应用。

TrackerService.java

public class TrackerService extends Service {

    private static final String TAG = TrackerService.class.getSimpleName();

    @Override
    public IBinder onBind(Intent intent) {return null;}

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

private void loginToFirebase() {

        // Authenticate with Firebase, and request location updates
        String email = getString(R.string.firebase_email);
        String password = getString(R.string.firebase_password);

        FirebaseAuth.getInstance().signInWithEmailAndPassword(
                email, password).addOnCompleteListener(new OnCompleteListener<AuthResult>(){
            @Override
            public void onComplete(Task<AuthResult> task) {
                if (task.isSuccessful()) {
                    Log.d(TAG, "firebase auth success");
                    requestLocationUpdates();
                } else {
                    Log.d(TAG, "firebase auth failed");
                }
            }
        });
    }

private void requestLocationUpdates() {

        LocationRequest request = new LocationRequest();
        request.setInterval(10000);
        request.setFastestInterval(5000);
        request.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        FusedLocationProviderClient client = LocationServices.getFusedLocationProviderClient(this);
        final String path = getString(R.string.firebase_path) + "/" + getString(R.string.transport_id);
        int permission = ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION);
        if (permission == PackageManager.PERMISSION_GRANTED) {
            // Request location updates and when an update is 
            // received, store the location in Firebase

            client.requestLocationUpdates(request, new LocationCallback() {
                @Override
                public void onLocationResult(LocationResult locationResult) {
                    DatabaseReference ref = FirebaseDatabase.getInstance().getReference(path);
                    Location location = locationResult.getLastLocation();
                    if (location != null) {
                        Log.d(TAG, "location update " + location);
                        ref.setValue(location);
                    }
                }
            }, null);
        }
    }

以下代码来自第二个在地图上显示标记的应用。

public class DisplayActivity extends FragmentActivity implements OnMapReadyCallback {

    private static final String TAG = DisplayActivity.class.getSimpleName();
    private HashMap<String, Marker> mMarkers = new HashMap<>();
    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_display);
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        // Authenticate with Firebase when the Google map is loaded
        mMap = googleMap;
        mMap.setMaxZoomPreference(16);
        loginToFirebase();
    }

    private void loginToFirebase() {
        String email = getString(R.string.firebase_email);
        String password = getString(R.string.firebase_password);
        // Authenticate with Firebase and subscribe to updates
        FirebaseAuth.getInstance().signInWithEmailAndPassword(
                email, password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(Task<AuthResult> task) {
                if (task.isSuccessful()) {
                    subscribeToUpdates();
                    Log.d(TAG, "firebase auth success");
                } else {
                    Log.d(TAG, "firebase auth failed");
                }
            }
        });
    }

 private void subscribeToUpdates() {
        DatabaseReference ref = FirebaseDatabase.getInstance().getReference(getString(R.string.firebase_path));
        ref.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
                setMarker(dataSnapshot);
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String previousChildName) {
                setMarker(dataSnapshot);
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
            }

            @Override
            public void onCancelled(DatabaseError error) {
                Log.d(TAG, "Failed to read value.", error.toException());
            }
        });
    }

    private void setMarker(DataSnapshot dataSnapshot) {
        // When a location update is received, put or update
        // its value in mMarkers, which contains all the markers
        // for locations received, so that we can build the 
        // boundaries required to show them all on the map at once

        String key = dataSnapshot.getKey();
        HashMap<String, Object> value = (HashMap<String, Object>) dataSnapshot.getValue();
        double lat = Double.parseDouble(value.get("latitude").toString());
        double lng = Double.parseDouble(value.get("longitude").toString());
        LatLng location = new LatLng(lat, lng);

        if (!mMarkers.containsKey(key)) {
            mMarkers.put(key, mMap.addMarker(new MarkerOptions().title(key).position(location)));
        } else {
            mMarkers.get(key).setPosition(location);
        }
        LatLngBounds.Builder builder = new LatLngBounds.Builder();
        for (Marker marker : mMarkers.values()) {
            builder.include(marker.getPosition());
        }
        mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(builder.build(), 300));
    }

Answer 1

在您的应用中，您可以创建一种方法来选择要删除的标记，方法是使用按钮或直接从地图中选择标记（我建议使用第二种方法），然后从mMarkers列表中删除标记，在映射并从firebase中删除“文档”。

对于“标记”部分，您可以遵循地图和标记的官方文档中的example。

对于Firebase部分，请检查how to remove data from RealTime Database，但基本上您会获得数据DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child(path)的数据库参考，并从其中调用removeValue ref.removeValue()

如何从地图和Firebase中删除特定标记？

1 个答案: