Java写一个socket服务端和客户端

以下是Java编写socket服务端和客户端的示例代码：

服务端：

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

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = null;

        try {
            // 创建ServerSocket对象，绑定端口号为8888
            serverSocket = new ServerSocket(8888);
        } catch (IOException e) {
            System.err.println("无法在端口8888上创建ServerSocket对象。");
            System.exit(-1);
        }

        Socket clientSocket = null;
        try {
            // 监听客户端连接请求，等待客户端连接
            System.out.println("等待客户端连接...");
            clientSocket = serverSocket.accept();
            System.out.println("客户端已连接。");
        } catch (IOException e) {
            System.err.println("无法接受客户端连接请求。");
            System.exit(-1);
        }

        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        String inputLine;

        // 接收客户端的消息，并回复
        while ((inputLine = in.readLine()) != null) {
            System.out.println("客户端：" + inputLine);
            out.println("服务端已接收到消息：" + inputLine);
        }

        // 关闭资源
        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}

客户端：

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

public class Client {
    public static void main(String[] args) throws IOException {
        Socket echoSocket = null;
        PrintWriter out = null;
        BufferedReader in = null;

        try {
            // 创建Socket对象，连接到服务端的8888端口
            echoSocket = new Socket("localhost", 8888);
            out = new PrintWriter(echoSocket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("无法连接到主机：localhost。");
            System.exit(-1);
        } catch (IOException e) {
            System.err.println("无法获得I/O流。");
            System.exit(-1);
        }

        // 向服务端发送消息，并接收回复
        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String userInput;
        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            System.out.println("服务端：" + in.readLine());
        }

        // 关闭资源
        out.close();
        in.close();
        stdIn.close();
        echoSocket.close();
    }
}

上述代码实现了一个简单的回显服务，客户端发送一条消息，服务端收到后再回复一条消息。你可以参考这个示例代码来编写更复杂的socket程序。