基于某些参数获取对另一个线程的引用

Question

我正在开发一个Java客户端/服务器聊天应用程序，允许局域网内的用户在他们之间聊天。

在服务器应用程序中，我有一个主类，每当客户端连接到服务器时，它都会创建一个不同的线程。所以，基本上，我会打开一个TCP连接，每个客户端都在一个单独的线程上运行。

我在发送消息时遇到问题。当用户向服务器发送新消息时，服务器必须找到与目标用户有连接的线程并将该消息发送给他。我该怎么做。我已经将每个线程与一个用户对象相关联，因此我需要执行类似findThreadByUser（user）的操作，并且在获得引用后，只需调用发送消息的方法。我该怎么做？

下面是实现Runnable的ConnectionHandler类的一部分。我想访问该类的特定实例，更具体地说，是它的末尾的方法< code > sendToClient(String message)(外部运行方法)。我尝试使用HashMap来存储用户和线程，但是我无法访问< code > sendToClient(String message)方法

public class ConnectionHandler implements Runnable {

protected Socket socket;
private ServerData serverData;
private User currentUser;
BufferedReader inFromClient;
PrintStream outToClient;
String clientSentence;
String peerIp;
String peerHostName;

public ConnectionHandler(Socket socketToHandle, ServerData serverData) {
    socket = socketToHandle;
    this.serverData = serverData;
    inFromClient = null;
    outToClient = null;
    currentUser = null;

    clientSentence = " ";
}

@Override
public void run() {
peerIp = socket.getInetAddress().getHostAddress();
    peerHostName = socket.getInetAddress().getHostName();
    try {
        outToClient = new PrintStream(socket.getOutputStream(), true);

        /* Create a reading stream to the socket */

        inFromClient = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    } catch (IOException ex) {
        Logger.getLogger(ConnectionHandler.class.getName()).log(Level.SEVERE, null, ex);
        System.out.println("Error creating buffered handles.");
    }

    System.out.println("Handling connection to client at " + peerIp + " --");

    Runnable r1 = new Runnable() {

        public void run() {
            while (true) {
                try {
                    /* Read client's message through the socket's input buffer */
                    clientSentence = inFromClient.readLine();
                } catch (IOException e) {
                    System.out.println(socket.getInetAddress() + "-" + peerIp + " broke the connection.");
                    break;
                }
                /* Output to screen the message received by the client */
                System.out.println("Message Received: " + clientSentence);

                List<String> processedClientSentence = ClientMessageProcessor.process(clientSentence);

                if (processedClientSentence.get(0).equals(new String("LOGIN"))) {
                    String result = ServerActions.login(peerIp, peerHostName, processedClientSentence.get(1), serverData);

                    if (result.equals("success")) {
                        currentUser = serverData.getUserByIP(peerIp);
                        outToClient.println("USERS \"" + ServerActions.getUsers(serverData) + "\"");
                    } else {
                        outToClient.println("ERROR \'" + result + "\'");
                    }
                } else if (processedClientSentence.get(0).equals(new String("GETUSERS"))) {
                    outToClient.println("USERS \"" + ServerActions.getUsers(serverData) + "\"");
                } else if (processedClientSentence.get(0).equals(new String("USERINFO"))) {
                } else if (processedClientSentence.get(0).equals(new String("MESSAGE"))) {
                    ServerActions.sendMessage(currentUser/*.getUserName()*/, processedClientSentence.get(1), processedClientSentence.get(2), serverData);
                } else if (processedClientSentence.get(0).equals(new String("LOGOUT"))) {
                } else {
                }

            }
        }
    };
    new Thread(r1).start();
}

public void sendToClient(String message) {
    outToClient.println(message);
}

}

Answer 1

为什么不发送广播，让正确的客户端接受消息呢？

Answer 2

将客户端对象存储在 HashMap 中，用户名（这将是唯一的）作为键，与之关联的线程作为值......”