如何使用Firebase数据库在Android中实现可见功能

Question

数据库-https://ibb.co/bWHzmy

我不是要如何将seen = false设置为true ...我的意思是这与聊天活动的onstart / oncreate有关...但是我显然希望看到的功能仅位于下面其他用户就像在任何消息传递应用程序上一样发短信...有人可以帮我实现该目标

保存消息

private void sendMessage() {
    String messageText = messageArea.getText().toString();
    if (TextUtils.isEmpty(messageText)) {
        Toast.makeText(getApplicationContext(), "Can't Send Blank Message", Toast.LENGTH_SHORT).show();
    } else {

        String message_sender_ref = "Messages/" + MessageSenderId + "/" + MessageRecieverId;
        String message_reciver_ref = "Messages/" + MessageRecieverId + "/" + MessageSenderId;

        Map messageTextBody = new HashMap<>();
        messageTextBody.put("Message", messageText);
        messageTextBody.put("Seen", false);
        messageTextBody.put("Type", "Text");
        messageTextBody.put("Time", ServerValue.TIMESTAMP);
        messageTextBody.put("From", MessageSenderId);

        DatabaseReference user_message_key = mDatabaseReference.child("Messages").child(MessageSenderId).child(MessageRecieverId).push();
        String message_push_id = user_message_key.getKey();

        Map messageBodyDetails = new HashMap();
        messageBodyDetails.put(message_sender_ref + "/" + message_push_id, messageTextBody);
        messageBodyDetails.put(message_reciver_ref + "/" + message_push_id, messageTextBody);

        mDatabaseReference.updateChildren(messageBodyDetails, new DatabaseReference.CompletionListener() {
            @Override
            public void onComplete(DatabaseError databaseError, DatabaseReference databaseReference) {
                if (databaseError != null) {
                    Log.d("Chat_Log", databaseError.getMessage().toString());
                }
                messageArea.setText("");
            }
        });
    }
}

获取消息

private void fetchMessages() {
    mDatabaseReference.child("Messages").child(MessageSenderId).child(MessageRecieverId).addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Messages message = dataSnapshot.getValue(Messages.class);
            messagesList.add(message);
            mAdapter.notifyDataSetChanged();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {
        }

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

        @Override
        public void onCancelled(DatabaseError databaseError) {
            throw databaseError.toException();
        }
    });
}