如何在Java Socket中实现多线程通信

在Java Socket中实现多线程通信，可以使用线程池来管理多个客户端连接。这里是一个简单的示例，展示了如何使用Java Socket和多线程实现服务器与多个客户端之间的通信。

1. 首先，创建一个处理客户端请求的Runnable类：

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

public class ClientHandler implements Runnable {
    private final Socket clientSocket;

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

    @Override
    public void run() {
        try (BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
             PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true)) {
            String inputLine;
            while ((inputLine = in.readLine()) != null) {
                System.out.println("Received from client: " + inputLine);
                out.println("Server received: " + inputLine);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                clientSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

2. 然后，创建一个服务器类，用于监听客户端连接并将每个连接分配给一个新的线程：

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MultiThreadedServer {
    public static void main(String[] args) {
        int port = 8080;
        ExecutorService executorService = Executors.newFixedThreadPool(10); // 创建一个固定大小的线程池

        try (ServerSocket serverSocket = new ServerSocket(port)) {
            System.out.println("Server started on port: " + port);

            while (true) {
                Socket clientSocket = serverSocket.accept(); // 接受客户端连接
                System.out.println("New client connected: " + clientSocket.getInetAddress());

                ClientHandler clientHandler = new ClientHandler(clientSocket);
                executorService.submit(clientHandler); // 将客户端处理任务提交给线程池
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            executorService.shutdown(); // 关闭线程池
        }
    }
}

3. 最后，创建一个客户端类，用于与服务器进行通信：

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

public class Client {
    public static void main(String[] args) {
        String hostname = "localhost";
        int port = 8080;

        try (Socket socket = new Socket(hostname, port);
             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
             BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))) {
            System.out.println("Connected to server");

            new Thread(() -> {
                try {
                    String serverMsg;
                    while ((serverMsg = in.readLine()) != null) {
                        System.out.println("Server: " + serverMsg);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }).start();

            String userInput;
            while ((userInput = stdIn.readLine()) != null) {
                out.println(userInput);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

现在，你可以运行服务器类和多个客户端类实例，它们将能够通过多线程通信。注意，这个示例仅用于演示目的，实际应用中需要考虑更多的错误处理和资源管理。