如何用Java进行TCP通信 Java客户端与服务器通信实例

import java.io.*;
import java.net.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class EchoServer {
    private static final int PORT = 8080;
    // 简单起见，这里用一个固定大小的线程池来处理客户端连接
    private static ExecutorService clientHandlerPool = Executors.newFixedThreadPool(10);

    public static void main(String[] args) {
        System.out.println("EchoServer 启动中...");
        try (ServerSocket serverSocket = new ServerSocket(PORT)) {
            System.out.println("服务器已在端口 " + PORT + " 监听。");

            while (true) {
                // 接受客户端连接，这是一个阻塞操作
                Socket clientSocket = serverSocket.accept();
                System.out.println("新客户端连接来自: " + clientSocket.getInetAddress().getHostAddress());

                // 将客户端处理任务提交给线程池
                clientHandlerPool.submit(new ClientHandler(clientSocket));
            }
        } catch (IOException e) {
            System.err.println("服务器启动或运行出错: " + e.getMessage());
            // 生产环境可能需要更详细的日志记录
        } finally {
            clientHandlerPool.shutdown(); // 关闭线程池
            System.out.println("EchoServer 已关闭。");
        }
    }

    private static class ClientHandler implements Runnable {
        private Socket clientSocket;

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

        @Override
        public void run() {
            try (
                BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true) // true for autoFlush
            ) {
                String inputLine;
                while ((inputLine = in.readLine()) != null) {
                    System.out.println("收到客户端 [" + clientSocket.getInetAddress().getHostAddress() + "] 消息: " + inputLine);
                    out.println("Echo from server: " + inputLine); // 回传给客户端
                    if ("bye".equalsIgnoreCase(inputLine.trim())) {
                        System.out.println("客户端 [" + clientSocket.getInetAddress().getHostAddress() + "] 请求断开连接。");
                        break;
                    }
                }
            } catch (IOException e) {
                System.err.println("处理客户端 [" + clientSocket.getInetAddress().getHostAddress() + "] 消息时出错: " + e.getMessage());
            } finally {
                try {
                    clientSocket.close(); // 关闭客户端连接
                    System.out.println("客户端 [" + clientSocket.getInetAddress().getHostAddress() + "] 连接已关闭。");
                } catch (IOException e) {
                    System.err.println("关闭客户端连接时出错: " + e.getMessage());
                }
            }
        }
    }
}

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class EchoClient {
    private static final String SERVER_IP = "127.0.0.1"; // 服务器IP地址
    private static final int PORT = 8080; // 服务器端口

    public static void main(String[] args) {
        System.out.println("EchoClient 启动中...");
        try (
            Socket socket = new Socket(SERVER_IP, PORT); // 连接服务器
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true); // true for autoFlush
            Scanner scanner = new Scanner(System.in) // 用于从控制台读取用户输入
        ) {
            System.out.println("已连接到服务器 " + SERVER_IP + ":" + PORT);
            String userInput;
            System.out.println("请输入消息，输入 'bye' 退出:");

            while (true) {
                System.out.print("你: ");
                userInput = scanner.nextLine(); // 读取用户输入

                out.println(userInput); // 发送消息到服务器

                String serverResponse = in.readLine(); // 读取服务器响应
                if (serverResponse != null) {
                    System.out.println("服务器: " + serverResponse);
                }

                if ("bye".equalsIgnoreCase(userInput.trim())) {
                    System.out.println("客户端请求退出。");
                    break;
                }
            }
        } catch (UnknownHostException e) {
            System.err.println("无法识别服务器IP地址: " + SERVER_IP + ", 错误: " + e.getMessage());
        } catch (IOException e) {
            System.err.println("连接服务器或通信出错: " + e.getMessage());
            // 常见的错误可能是服务器未启动或端口被占用
        } finally {
            System.out.println("EchoClient 已关闭。");
        }
    }
}