How to use network functions in Java for network programming

How to use network functions for network programming in Java

Network programming is a programming method for data exchange on a computer network. It can realize the communication between different computers. communication and data transmission. In Java, we can use network functions to implement network programming. This article will introduce how to use Java's network functions for network programming and provide some specific code examples.

1. Basic knowledge of Java network functions
To perform network programming in Java, we need to use the classes and methods in the java.net package provided by Java. Among them, the most commonly used are the Socket and ServerSocket classes. The Socket class represents a client connection and is responsible for communicating with the server; the ServerSocket class is responsible for listening and accepting client connection requests.

2. Establish client connection
The following is a simple client code example to connect to the specified server and send data:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class Client {
    public static void main(String[] args) {
        String serverAddress = "127.0.0.1"; // 服务器IP地址
        int serverPort = 12345; // 服务器端口号

        try {
            // 创建Socket对象，连接服务器
            Socket socket = new Socket(serverAddress, serverPort);
            
            // 获取输入输出流
            InputStream inputStream = socket.getInputStream();
            OutputStream outputStream = socket.getOutputStream();
            
            // 向服务器发送数据
            outputStream.write("Hello Server".getBytes());
            
            // 接收服务器返回的数据
            byte[] buffer = new byte[1024];
            int len = inputStream.read(buffer);
            String receivedData = new String(buffer, 0, len);
            System.out.println("Received from server: " + receivedData);
            
            // 关闭连接
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

3. Create server side
The following is a simple server-side code example that listens to the specified port and accepts client connections, and sends a response to the client after receiving the client data:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) {
        int serverPort = 12345; // 服务器端口号

        try {
            // 创建ServerSocket对象，监听端口
            ServerSocket serverSocket = new ServerSocket(serverPort);
            System.out.println("Server started and listening on port " + serverPort);

            while (true) {
                // 接受客户端连接
                Socket socket = serverSocket.accept();
                System.out.println("Accepted connection from " + socket.getInetAddress());

                // 获取输入输出流
                InputStream inputStream = socket.getInputStream();
                OutputStream outputStream = socket.getOutputStream();

                // 接收客户端发送的数据
                byte[] buffer = new byte[1024];
                int len = inputStream.read(buffer);
                String receivedData = new String(buffer, 0, len);
                System.out.println("Received from client: " + receivedData);

                // 向客户端发送响应
                outputStream.write("Hello Client".getBytes());

                // 关闭连接
                socket.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4. Summary
By using Java's network functions, we can easily implement network programming and enable data communication and transmission between different computers. In this article, we introduced how to use Java's Socket and ServerSocket classes to establish client connections and create server sides. I hope these code examples can help readers better understand and apply Java's network functions for network programming.

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