Question

我正在尝试根据this教程使用Firebase构建实时聊天应用。根据教程，这行代码

mDatabaseReference.child(MESSAGES_CHILD).child(key!!).setValue(message)

应该将消息对象中存在的数据写到数据库中。

一切正常，除了当用户按下发送按钮时，文本没有上载到数据库（但是正在创建密钥，并且当我手动在数据库中手动搜索该密钥时，那里只有null存储）。

这是 ChatActivity.kt

的最小代码

private const val TAG = "ChatActivity"
const val MESSAGES_CHILD = "messages"

class ChatActivity : AppCompatActivity() {

    private lateinit var mChatAdapter: ChatAdapter
    private lateinit var mLinearLayoutManager: LinearLayoutManager

    private lateinit var mDatabaseReference: DatabaseReference
    private lateinit var mFirebaseAuth: FirebaseAuth

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_chat)
        
        mFirebaseAuth = FirebaseAuth.getInstance()
        Log.d(TAG, "onCreate: \n Auth: $mFirebaseAuth")
        mDatabaseReference = FirebaseDatabase.getInstance().reference

        mLinearLayoutManager = LinearLayoutManager(this)
        mChatAdapter = ChatAdapter(options)
        //ChatAdapter extends FirebaseRecyclerAdapter

        chat.apply {  //R.id.chat
            setHasFixedSize(true)
            layoutManager = mLinearLayoutManager
            adapter = mChatAdapter
        }

        send_button.setOnClickListener {
            val message = Message(message_entry.text.trim().toString())
            Log.d(TAG, "onCreate: \n $message")

            val key = mDatabaseReference.child(MESSAGES_CHILD).push().key
            Log.d(TAG, "onCreate: \n Key: $key")
            mDatabaseReference.child(MESSAGES_CHILD). child(key!!).setValue(message)
        }
    }

    override fun onPause() {
        mChatAdapter.stopListening()
        Log.d(TAG, "onPause: ")
        super.onPause()
    }

    override fun onResume() {
        super.onResume()
        Log.d(TAG, "onResume: ")
        mChatAdapter.startListening()
    }
}

@IgnoreExtraProperties
data class Message(var text: String?= "", var name: String?= "", var id: String?= "") {

    override fun toString(): String {
        return "Text: $text \n Name: $name \n Id: $id"
    }
}

这是应用程序调试详细信息

2020-10-17 11:18:34.294 5168-5168/com.skb.skara D/ChatActivity: onCreate:  
Auth: com.google.firebase.auth.internal.zzn@5a3e651  
2020-10-17 11:18:34.338 5168-5168/com.skb.skara D/ChatActivity: onResume:  
2020-10-17 11:18:34.389 5168-5168/com.skb.skara D/ChatAdapter:     getItemCount: 0  
2020-10-17 11:18:34.389 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 0  
2020-10-17 11:18:37.435 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 0  
2020-10-17 11:18:37.435 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 0  
2020-10-17 11:18:42.033 5168-5168/com.skb.skara D/ChatActivity: onCreate:  
Text: Hi  
Name:  
Id:  
2020-10-17 11:18:42.033 5168-5168/com.skb.skara D/ChatActivity: onCreate:  
Key: -MJp5_ulT4U6cXU9Eu41  
2020-10-17 11:18:42.056 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 1  
2020-10-17 11:18:42.071 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 1  
2020-10-17 11:18:42.072 5168-5168/com.skb.skara D/ChatAdapter: getItemCount: 1_

这是我的数据库规则

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null"
  }
}

Answer 1

尝试一下：

def checkOffWindowX(x) :
    return x % windowsize[0]

def checkOffWindowY(y):
    return y % windowsize[1]

String key = mDatabaseReference.child(MESSAGES_CHILD).push().getKey(); mDatabaseReference.child(MESSAGES_CHILD).child(key).setValue(message);表示消息的新ID。

更新：将您的消息对象转换为地图：

key

有关read and write进入实时数据库的更多信息

Answer 2

今天，我解决了问题中所述的问题。实际的问题不在代码中，而是在我用来运行应用程序的仿真器中。 This链接提到了将Firebase添加到android studio项目的前提条件。在那我忘了验证我的模拟器上是否有Google Play图像。今天，当我再次进行交叉验证的先决条件时，我发现了问题，并在解决了问题之后，现在将数据上传到了Firebase。

将文本数据上传到Firebase实时数据库

2 个答案: