java - 在Firebase和Android Studio中检索驾驶员的passengerRequest节点内的所有乘客ID(用户ID)

Question

我正在尝试检索并将其转换为保存在驱动程序乘客请求中的 UserID 字符串，如下图所示:

/image/ztATh.jpg

这是我的 getAssignPassenger

private void getAssignedPassenger() {
    String driverID = FirebaseAuth.getInstance().getCurrentUser().getUid();
    DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users").child("Driver").child(driverID).child("passengerRequest");
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {

                passengerID = dataSnapshot.getValue().toString();
                getAssignPassengerPickUpLocation();
            }else{
                passengerID = "";
                if(pickupMarker !=null){
                    pickupMarker.remove();
                }
                if(AssignPassengerPickupLocationListener!= null){
                AssignPassengerPickupLocationref.removeEventListener(AssignPassengerPickupLocationListener);
            }}
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

我的问题就在这个 block

DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users").child("Driver").child(driverID).child("passengerRequest");
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {

                passengerID = dataSnapshot.getValue().toString();
                getAssignPassengerPickUpLocation();

在passengerID中，它应该检索保存在其中的每个用户ID...我该怎么办？

下一个问题是...如果我成功检索了用户 ID，以及如何继续查找其位置，这是节点的图片:

/image/Kvbhi.jpg

我已经开始编写它的代码

这是我的 getAssignPassengerLocation

private void getAssignPassengerPickUpLocation() {

    AssignPassengerPickupLocationref = FirebaseDatabase.getInstance().getReference().child("passengerRequest").child(passengerID).child("l");
    AssignPassengerPickupLocationListener = AssignPassengerPickupLocationref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()&&!passengerID.equals("")) {
                List<Object> map = (List<Object>) dataSnapshot.getValue();
                double locationLat = 0;
                double locationLong = 0;

                if (map.get(0) != null) {
                    locationLat = Double.parseDouble(map.get(0).toString());
                }
                if (map.get(1) != null) {
                    locationLong = Double.parseDouble(map.get(1).toString());
                }
                LatLng driverLatLng = new LatLng(locationLat, locationLong);

                mMap.addMarker(new MarkerOptions().position(driverLatLng).title("Pickup Location").icon(BitmapDescriptorFactory.fromResource(R.mipmap.ic_launcher_pickup_marker)));

我应该在这个 block 做什么

AssignPassengerPickupLocationref = FirebaseDatabase.getInstance().getReference().child("passengerRequest").child(passengerID).child("l");
    AssignPassengerPickupLocationListener = AssignPassengerPickupLocationref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()&&!passengerID.equals("")) {
                List<Object> map = (List<Object>) dataSnapshot.getValue();
                double locationLat = 0;
                double locationLong = 0;

是否可以将节点存储在数组字符串中？

Answer 1

对于第一个

您必须在快照中获取快照子项

private void getAssignedPassenger() {
    String driverID = FirebaseAuth.getInstance().getCurrentUser().getUid();
    DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users").child("Driver").child(driverID).child("passengerRequest");
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {
                List<String> passengerIdList = new ArrayList()
                for (DataSnapshot passenger Snapshot: dataSnapshot.getChildren()) {
                    String passengerId = passenger.getKey()
                    passengerIdList.add(passengerId)
                }
                getAssignPassengerPickUpLocation();
            }else{
                passengerID = "";
                if(pickupMarker !=null){
                    pickupMarker.remove();
                }
                if(AssignPassengerPickupLocationListener!= null){
                AssignPassengerPickupLocationref.removeEventListener(AssignPassengerPickupLocationListener);
            }}
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

第二个

实际上，您必须将位置保持与“目的地”相同的位置，而不是在另一个子级中查询。

但是为什么您需要同时获取所有用户请求位置或者在您的 Activity 中将所有用户请求位置包含在一个 Activity 中？

了解更多信息:

读取和写入列表

https://firebase.google.com/docs/database/android/lists-of-data

和

如何构建NoSQL

https://www.youtube.com/watch?v=v_hR4K4auoQ