如何在Firebase中的多个子项中推送相同的值？

Question

我在我的Android应用上使用firebase。我创建了一个群聊应用程序。当用户创建组时，已将组名child添加到创建该组的用户的孩子中。群组所有者添加了一些朋友后，群组名称child已添加到朋友的孩子中。但是，当用户向组发送消息时，该消息将仅将发送方用户ID中的组子项推入。我希望当用户向组发送消息时，该消息将推送所有组成员子级。我该怎么办？

My Database Picture

以下是我的代码：

  

GroupChatActivity.java：

package com.example.whatsapp2;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ScrollView;
import android.widget.TextView;
import android.support.v7.widget.Toolbar;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Iterator;

public class GroupChatActivity extends AppCompatActivity {
    private Toolbar mToolbar;
    private ImageButton SendMessageButton;
    private EditText userMessageInput;
    private ScrollView mScrollView;
    private TextView displayTextMessages;
    private String currentGroupName;
    private FirebaseAuth mAuth;
    private DatabaseReference UserRef, GroupNameRef, GroupMessageKeyRef;
    private String currentUserID, currentUserName, currentDate, currentTime;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_group_chat);

        //currentGroupName = getIntent().getExtras().getString("groupName");
        currentGroupName = getIntent().getExtras().get("groupName").toString();
        Toast.makeText(this,currentGroupName,Toast.LENGTH_SHORT).show();

        mAuth = FirebaseAuth.getInstance();
        currentUserID = mAuth.getCurrentUser().getUid();
        UserRef = FirebaseDatabase.getInstance().getReference().child("Users");
        GroupNameRef = FirebaseDatabase.getInstance().getReference().child("Groups").child(currentUserID).child(currentGroupName);
        InitializeFields();
        GetUserInfo();
        SendMessageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SaveMessageInfoToDatabase();
                userMessageInput.setText("");
                mScrollView.fullScroll(ScrollView.FOCUS_DOWN);
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        GroupNameRef.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
                if(dataSnapshot.exists()){
                    DisplayMessages(dataSnapshot);
                }
            }

            @Override
            public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
                if(dataSnapshot.exists()){
                    DisplayMessages(dataSnapshot);
                }
            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.group_menu,menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        super.onOptionsItemSelected(item);
        if(item.getItemId() == R.id.group_add_friends_option){
            SendUserToAddPeopleActivity();
        }
        return true;
    }

    private void SendUserToAddPeopleActivity() {
        Intent addPeopleIntent = new Intent(this,AddPeopleActivity.class);
        Bundle data1 = new Bundle();
        data1.putString("groupName",currentGroupName);
        addPeopleIntent.putExtras(data1);
        startActivity(addPeopleIntent);
    }

    private void DisplayMessages(DataSnapshot dataSnapshot) {
        Iterator iterator = dataSnapshot.getChildren().iterator();
        while (iterator.hasNext()){
            String chatDate = (String) ((DataSnapshot)iterator.next()).getValue();
            String chatMessage = (String) ((DataSnapshot)iterator.next()).getValue();
            String chatName = (String) ((DataSnapshot)iterator.next()).getValue();
            String chatTime = (String) ((DataSnapshot)iterator.next()).getValue();

            displayTextMessages.append(chatName+ " :\n"+chatMessage+"\n"+chatTime+"    "+chatDate+"\n\n\n");
            mScrollView.fullScroll(ScrollView.FOCUS_DOWN);
        }
    }

    private void SaveMessageInfoToDatabase() {
        String message = userMessageInput.getText().toString();
        String messageKey = GroupNameRef.push().getKey();
        if(TextUtils.isEmpty(message)){
            Toast.makeText(this,"Please write message first...",Toast.LENGTH_SHORT).show();
        }
        else {
            Calendar calForDate = Calendar.getInstance();
            SimpleDateFormat currentDateFormat = new SimpleDateFormat("MMM dd, yyyy");
            currentDate = currentDateFormat.format(calForDate.getTime());

            Calendar calForTime = Calendar.getInstance();
            SimpleDateFormat currentTimeFormat = new SimpleDateFormat("hh:mm a");
            currentTime = currentTimeFormat.format(calForTime.getTime());

            HashMap<String,Object> groupMessageKey = new HashMap<>();
            GroupNameRef.updateChildren(groupMessageKey);
            GroupMessageKeyRef = GroupNameRef.child(messageKey);

            HashMap<String,Object> messageInfoMap = new HashMap<>();
            messageInfoMap.put("name",currentUserName);
            messageInfoMap.put("message",message);
            messageInfoMap.put("date",currentDate);
            messageInfoMap.put("time",currentTime);
            GroupMessageKeyRef.updateChildren(messageInfoMap);
        }
    }

    private void GetUserInfo() {
        UserRef.child(currentUserID).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                if(dataSnapshot.exists()){
                    currentUserName = dataSnapshot.child("name").getValue().toString();
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    private void InitializeFields() {
        mToolbar = findViewById(R.id.group_chat_bar_layout);
        setSupportActionBar(mToolbar);
        getSupportActionBar().setTitle(currentGroupName);
        SendMessageButton =findViewById(R.id.send_message_button);
        userMessageInput = findViewById(R.id.input_group_message);
        mScrollView = findViewById(R.id.my_scroll_view);
        displayTextMessages = findViewById(R.id.group_chat_text_display);
    }
}

  

GroupsFragment.java：

package com.example.whatsapp2;


import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;


/**
 * A simple {@link Fragment} subclass.
 */
public class GroupsFragment extends Fragment {
    private View groupFragmentView;
    private ListView list_view;
    private ArrayAdapter<String> arrayAdapter;
    private ArrayList<String> list_of_groups = new ArrayList<>();
    private DatabaseReference GroupRef;
    private FirebaseAuth mAuth;
    private String currentUserId;

    public GroupsFragment() {
        // Required empty public constructor
    }


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

        groupFragmentView = inflater.inflate(R.layout.fragment_groups, container, false);
        mAuth = FirebaseAuth.getInstance();
        currentUserId = mAuth.getCurrentUser().getUid();
        GroupRef = FirebaseDatabase.getInstance().getReference().child("Groups").child(currentUserId);
        InitializeFields();
        RetrieveAndDisplayGroups();
        list_view.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                String currentGroupName = parent.getItemAtPosition(position).toString();
                Intent groupChatIntent = new Intent(getContext(),GroupChatActivity.class);
                /*Bundle data1 = new Bundle();
                /*if(groupChatIntent !=null){
                    data1.putString("groupName",currentGroupName);
                    groupChatIntent.putExtras(data1);
                }*/
                /*data1.putString("groupName",currentGroupName);
                groupChatIntent.putExtras(data1);*/
                groupChatIntent.putExtra("groupName",currentGroupName);
                startActivity(groupChatIntent);
            }
        });
        return groupFragmentView;
    }

    private void RetrieveAndDisplayGroups() {
        GroupRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                Set<String> set = new HashSet<>();
                Iterator iterator = dataSnapshot.getChildren().iterator();
                while (iterator.hasNext()){
                    set.add(((DataSnapshot)iterator.next()).getKey());
                }
                list_of_groups.clear();
                list_of_groups.addAll(set);
                arrayAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    private void InitializeFields() {
        list_view = groupFragmentView.findViewById(R.id.list_view);
        arrayAdapter = new ArrayAdapter<String>(getContext(),android.R.layout.simple_list_item_1,list_of_groups);
        list_view.setAdapter(arrayAdapter);
    }

}