如何在应用程序的地图上显示动画驾驶汽车

Question

我的数据库

在上面的树中，我存储了驱动程序可用的当前纬度和经度。如果在 driversAvailable 树下存在多个驱动程序，那么如何在地图上显示所有驱动程序？到目前为止，我已经编写了以下代码，但它无法正常工作：

private DatabaseReference driverLoadLocationRef;
private ValueEventListener driverLoadLocationRefListener;
private void loadAllAvailableDrivers() {
    DatabaseReference driverLoading = FirebaseDatabase.getInstance().getReference().child("driversAvailable");
    GeoFire geoDriver = new GeoFire(driverLoading);
    GeoQuery geoQueryDriver = geoDriver.queryAtLocation(new GeoLocation(mLastLocation.getLatitude(),mLastLocation.getLongitude()),distance);
    geoQueryDriver.removeAllListeners();
    geoQueryDriver.addGeoQueryEventListener(new GeoQueryEventListener() {
        @Override
        public void onKeyEntered(final String key, GeoLocation location) {
            if (!driverLoad ) {
                driverLoad = true;
                driverLoadId = key;
                driverLoadLocationRef = FirebaseDatabase.getInstance().getReference().child("driversAvailable").child(driverFoundId).child("l");
                driverLoadLocationRefListener = driverLoadLocationRef.addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        if (dataSnapshot.exists() ) //If doesnot exist check then app will crash
                        {
                            List<object> map = (List<object>) dataSnapshot.getValue();
                            double locationLoadLat = 0;
                            double locationLoadLng = 0;
                            if (map.get(0) != null)
                            {
                                locationLoadLat = Double.parseDouble(map.get(0).toString());
                            }
                            if (map.get(1) != null)
                            {
                                locationLoadLng = Double.parseDouble(map.get(1).toString());
                            }
                            LatLng driverLoadLatLng = new LatLng(locationLoadLat,locationLoadLng);
                            if (mDriverMarker != null) //If not added app crash since it will try to remove which doesnot exist
                            {
                                mDriverMarker.remove();
                            }
                            mDriverMarker = mMap.addMarker(new MarkerOptions().position(driverLoadLatLng).flat(true)
                                    .title(driverLoadId)
                                    .icon(BitmapDescriptorFactory.fromResource(R.drawable.car3)));
                        }
                    }
                    @Override
                    public void onCancelled(DatabaseError databaseError) {
                        Toast.makeText(PassengerMapsActivity.this,"Failed",Toast.LENGTH_SHORT).show();
                    }
                });
            }
        }
        @Override
        public void onKeyExited(String key) {
        }
        @Override
        public void onKeyMoved(String key, GeoLocation location) {
        }
        @Override
        public void onGeoQueryReady() {
            if (distance <= LIMIT)
            {
                distance++;
                loadAllAvailableDrivers();
            }
        }
        @Override
        public void onGeoQueryError(DatabaseError error) {
        }
    });
}

Answer 1

我认为我有更简单的实现方式！

创建一个Marker数组，用onDataChange的条目数（childrenCount）初始化数组。 之后，在 'for(DataSnapshot ds : dataSnapshot.getChildren())' 中嵌入另一个 for..loop，迭代找到的条目数（childrenCount）。

我假设您有一个用于将数据推送到 firebase 的 Model 类。使用它来检索特定的坐标。 Av 决定将您的 '0' 和 '1' 替换为 'lat' 和 'lon'。

private void loadAllAvailableDrivers() {
DatabaseReference driverLoading = FirebaseDatabase.getInstance().getReference("driversAvailable");
driverLoading.addValueEventListener(new ValueEventListener() {
    @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            //trying to get several markers
            //Create an array and specify a size which will be initialized to children(driver) count
            int size = (int) dataSnapshot.getChildrenCount(); //
            Marker[] allMarkers = new Marker[size];
            map.clear();
            for(DataSnapshot ds : dataSnapshot.getChildren()) {
               //Specify your model class here
                ModelClass modelObject=new ModelClass();
                //lets create a loop
                 for(int i=0;i<=size;i++) {
                    try {
                        //am assuming the model class uses variable 'lat',lon,name
                         modelObject.setLat(ds.getValue(ModelClass.class).getLat());
                         modelObject.setLon(ds.getValue(ModelClass.class).getLon());
                         modelObject.setName(ds.getValue(ModelClass.class).getName());

                        //lets retrieve the coordinates and store them in a variable
                        String myName=modelObject.getName();
                        Double latitude = Double.parseDouble(modelObject.getLat());
                        Double longitude = Double.parseDouble(modelObject.getLon());

                        //convert the coordinates to LatLng
                        LatLng latLng = new LatLng(latitude, longitude);
                        map.setMapType(GoogleMap.MAP_TYPE_NORMAL);

                        //Now lets add updated markers
                        //lets add updated marker
                     allMarkers[i] = map.addMarker(new MarkerOptions()
                             .icon(BitmapDescriptorFactory.fromResource(R.drawable.car3)).position(latLng).title(myName));
                 }catch (Exception ex){}
                 }


           }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            Toast.makeText(PassengerMapsActivity.this,"Failed",Toast.LENGTH_SHORT).show();

        }
    });
 }