用java让客户端和服务端建立连接

可以使用 Java 中的 Socket 类来建立客户端和服务端之间的连接。以下是一个简单的示例代码：

客户端：

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

public class Client {
    public static void main(String[] args) {
        try {
            Socket socket = new Socket("localhost", 8888);
            System.out.println("Connected to server");

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

            out.println("Hello server");
            String response = in.readLine();
            System.out.println("Server response: " + response);

            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

服务端：

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

public class Server {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(8888);
            System.out.println("Server started");

            Socket socket = serverSocket.accept();
            System.out.println("Client connected");

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

            String request = in.readLine();
            System.out.println("Client request: " + request);

            out.println("Hello client");

            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

这段代码可以让客户端和服务端建立连接，并在连接建立后互相发送消息。