Java NIO - 使用SocketChannel接收數據的問題

Question

我正在使用Java NIO編寫簡單的即時通訊程序。它的正常工作exept客戶端不與已經被記錄在通訊錄中獲取消息
這是主要的服務器進程方法：

public void process() throws IOException, ClassNotFoundException{ 
    while (true){ 
     selector.select(); 
     Set keys = selector.selectedKeys(); 
     Iterator it = keys.iterator(); 
     while (it.hasNext()){ 
      SelectionKey key = (SelectionKey)it.next(); 
      it.remove(); 
      if (key.isAcceptable()){ 
       /*configuring incoming channel to be non-blocking 
       and adding it to the clients set*/ 
      } 
      if (key.isReadable()) { 
       SocketChannel client = (SocketChannel)key.channel(); 
       /*Message class contains its type, source user name and data. 
       getMessage() method reads message from SocketChannel*/ 
       Message m = getMessage(client);  
       switch (m.getType()) { 
        case LOGIN_REQUESTED: 
         /*Accept or reject the client log in name 
         in case of accepting add user with its status 
         to Map users*/ 
         break; 
        case CONTACTS_REQUESTED: 
         /*Here is the problem, client gets only one message 
         sendMessage() writes the buffer with serialized 
         message to clients channels*/ 
         for (String name : users.keySet()) { 
          sendMessage(client, MessageType.CONTACTS_REQUESTED, 
           name, users.get(name).toString()); 
         } 
         break; 
        //Other messages are processing 
       } 
      } 
     } 
    } 
} 

客戶端的方法，它處理收到的消息：

private void processIncomingMessages() 
    throws IOException, ClassNotFoundException { 
    ByteArrayInputStream bais; 
    ObjectInputStream ois; 
    ByteBuffer buffer = ByteBuffer.allocate(BUFFER_SIZE); 
    while (true){ 
     selector.select(); 
     Set keys = selector.selectedKeys(); 
     Iterator it = keys.iterator(); 
     while (it.hasNext()){ 
      SelectionKey key = (SelectionKey)it.next(); 
      it.remove(); 
      if (key.isReadable()){ 
       SocketChannel sc = (SocketChannel)key.channel(); 
       buffer.clear(); 
       if (sc.read(buffer) != -1){ 
        buffer.flip(); 
        bais = new ByteArrayInputStream(buffer.array()); 
        ois = new ObjectInputStream(bais); 
        Message m = (Message)ois.readObject(); 
        /*My castom event serves to notify GUI to update 
        its contact list. In case of sending CONTACTS_REQUESTED 
        messages, it gets only one (first?) of them*/ 
        fireNetworkEvent(m); 
       } 
      } 
     } 
    } 
} 

其他消息分開發送給客戶端，沒有任何問題。 如果有任何問題，請詢問。任何幫助將不勝感激

Answer 1

我的猜測是，在客戶端...

if (sc.read(buffer) != -1){ 

不能保證讀你的整個消息，它可以讀取什麼，它的一些或多個消息。

套接字是字節流，如果你想讀取一個數據包（和你一樣），你需要打包數據流。

要做到這一點的一種方法是預先確定數據包的長度，並確保在嘗試處理之前閱讀整個數據包。

另一種方式是編寫數據包，使其具有獨特的終止符，直到獲得終止符。