Untitled

import java.net.*;
import java.io.*;

public class MultiThreadServer {
    public static void main(String[] args) throws IOException {
        try (ServerSocket serverSocket = new ServerSocket(12345)) {
            System.out.println("服务器已启动，监听端口：12345");
            
            while (true) {
                Socket clientSocket = serverSocket.accept();
                new ClientHandler(clientSocket).start();
            }
        }
    }

    private static class ClientHandler extends Thread {
        private final Socket socket;

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

        public void run() {
            try (BufferedReader in = new BufferedReader(
                    new InputStreamReader(socket.getInputStream()));
                 PrintWriter out = new PrintWriter(
                    socket.getOutputStream(), true)) {
                
                String clientIP = socket.getInetAddress().getHostAddress();
                System.out.println("客户端[" + clientIP + "]已连接");

                String inputLine;
                while ((inputLine = in.readLine()) != null) {
                    System.out.println("收到消息：" + inputLine);
                    
                    // 业务处理逻辑
                    String response = "服务器响应：" + inputLine.toUpperCase();
                    out.println(response);
                }
            } catch (IOException e) {
                System.err.println("连接异常：" + e.getMessage());
            } finally {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}