技術標籤：Java計算機網路基礎udpjava網路通訊

Java實現UDP通訊

環境

CentOS Linux release 8.1.1911 (Core)
java version "14.0.2" 2020-07-14

程式碼

伺服器端的Server程式需先於客戶端的Client程式執行

Client

其中，<host name>為伺服器端IP地址，<port>為伺服器程式監聽的埠號

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

public class UDPClient
 
 {
    private String hostName;
    private int port;
    private DatagramSocket datagramSocket;


    public UDPClient(String hostName, int port) {
        this.hostName = hostName;
        this.port = port;

        try {
            datagramSocket = new DatagramSocket();
        } catch (SocketException
 
 e) {
            e.printStackTrace();
        }
    }

    public void sendMessage(String message) {
        byte[] buffer = message.getBytes();
        try {
            DatagramPacket datagramPacket = new DatagramPacket(buffer, buffer.length, InetAddress.getByName(hostName), port);
            datagramSocket.
 
send(datagramPacket);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        final String HOST_NAME = "<host name>";
        final int PORT = <port>;
        UDPClient udpClient = new UDPClient(HOST_NAME, PORT);

        String message = "";

        while (!message.equals("exit")) {
            Scanner scanner = new Scanner(System.in);
            message = scanner.nextLine();

            udpClient.sendMessage(message);
        }
    }
}

Server

其中，<port>為程式監聽的埠號，需與客戶端設定的一致

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

public class UDPServer {
	private int port;
	private DatagramSocket datagramSocket;

	public UDPServer(int port) {
		this.port = port;
		try {
			datagramSocket = new DatagramSocket(port);
		} catch (SocketException e) {
			e.printStackTrace();
		}
	}

	public String receive() {
		byte[] buffer = new byte[1024];
		DatagramPacket datagramPacket = new DatagramPacket(buffer, buffer.length);

		try {
			datagramSocket.receive(datagramPacket);
		} catch (IOException e) {
			e.printStackTrace();
		}
		String message = new String(datagramPacket.getData(), 0, datagramPacket.getLength());
		return message;
	}

    public static void main(String[] args) throws Exception
	{
		String message = "";
		UDPServer udpServer = new UDPServer(<port>);
		while (!message.equals("exit")) {
			message = udpServer.receive();
			System.out.println(message);
		}
	}

}

雲伺服器安全組配置

安全組訪問規則入方向協議型別需設定為UDP

測試結果

Client

Hello
This is Client!
exit

Server

Hello
This is Client!
exit

最後

• 由於博主水平有限，不免有疏漏之處，歡迎讀者隨時批評指正，以免造成不必要的誤解！