java socket 通信客户端和服务器端

Java中可以通过Socket实现客户端和服务器端之间的网络通信。下面是一个简单的例子：

服务器端：

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

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(8888);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 8888.");
            System.exit(1);
        }

        Socket clientSocket = null;
        try {
            System.out.println("Waiting for connection...");
            clientSocket = serverSocket.accept();
            System.out.println("Connection established with: " + clientSocket.getInetAddress().getHostAddress());
        } catch (IOException e) {
            System.err.println("Accept failed.");
            System.exit(1);
        }

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

        String inputLine, outputLine;
        while ((inputLine = in.readLine()) != null) {
            System.out.println("Received message: " + inputLine);
            outputLine = "Server received message: " + inputLine;
            out.println(outputLine);
            if (outputLine.equals("bye"))
                break;
        }

        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}

客户端：

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

public class Client {
    public static void main(String[] args) throws IOException {

        Socket socket = null;
        PrintWriter out = null;
        BufferedReader in = null;

        try {
            socket = new Socket("localhost", 8888);
            out = new PrintWriter(socket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Unknown host: localhost.");
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: localhost.");
            System.exit(1);
        }

        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String userInput;
        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            String serverResponse = in.readLine();
            System.out.println("Server response: " + serverResponse);
            if (serverResponse.equals("bye"))
                break;
        }

        out.close();
        in.close();
        stdIn.close();
        socket.close();
    }
}

以上代码实现了一个简单的客户端和服务器端的通信，可以通过命令行输入消息进行交互。