Java群聊聊天室实现教程详解

public class ChatServer {
    private Set clientWriters = new HashSet<>();

    public void start() throws IOException {
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("服务器启动，等待连接...");

        while (true) {
            Socket socket = serverSocket.accept();
            new ClientHandler(socket).start();
        }
    }

    private class ClientHandler extends Thread {
        private Socket socket;
        private PrintWriter writer;

        public ClientHandler(Socket socket) {
            this.socket = socket;
        }

        public void run() {
            try {
                BufferedReader reader = new BufferedReader(
                    new InputStreamReader(socket.getInputStream())
                );
                writer = new PrintWriter(socket.getOutputStream(), true);

                synchronized (clientWriters) {
                    clientWriters.add(writer);
                }

                String message;
                while ((message = reader.readLine()) != null) {
                    if ("quit".equalsIgnoreCase(message)) break;
                    // 广播消息
                    for (PrintWriter w : clientWriters) {
                        w.println(message);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (writer != null) {
                    synchronized (clientWriters) {
                        clientWriters.remove(writer);
                    }
                }
                try {
                    socket.close();
                } catch (IOException e) {}
            }
        }
    }
}

public class ChatClient {
    private Socket socket;
    private BufferedReader inputReader;
    private PrintWriter outputWriter;

    public void connect() throws IOException {
        socket = new Socket("localhost", 8888);
        inputReader = new BufferedReader(new InputStreamReader(System.in));
        outputWriter = new PrintWriter(socket.getOutputStream(), true);
        
        // 启动接收线程
        new MessageListener().start();

        // 主线程发送消息
        String msg;
        while ((msg = inputReader.readLine()) != null) {
            outputWriter.println(msg);
            if ("quit".equalsIgnoreCase(msg)) break;
        }
    }

    private class MessageListener extends Thread {
        public void run() {
            try {
                BufferedReader in = new BufferedReader(
                    new InputStreamReader(socket.getInputStream())
                );
                String msg;
                while ((msg = in.readLine()) != null) {
                    System.out.println("[群聊]" + msg);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}