Java监听指定端口通过udp协议接收与发送报文

创建服务端用于监听端口

import com.lanlinker.netty.paycard.entity.DoorSendMessage;
import com.lanlinker.netty.paycard.util.HexConvert;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;


/**
 * @author aaron
 * @since 2021-01-27
 */
@Slf4j
public class UdpServer {
          
   


    public static void main(String[] args) throws IOException {
          
   
        socketListener();
    }

    public static void socketListener() throws IOException {
          
   
        log.info("端口监听进程开始启动");
        //创建socket
        DatagramSocket socket = new DatagramSocket(8800);
        byte[] buf = new byte[64];
        try {
          
   
            //创建数据包
            DatagramPacket recPacket = new DatagramPacket(buf, buf.length);
            //接受数据
            socket.receive(recPacket);
            InetAddress address = recPacket.getAddress();
            String targetIp = address.getHostAddress();
            int targetPort = recPacket.getPort();
            log.info("=========接收到来自" + targetIp + ":" + targetPort + "的消息:" + HexConvert.BinaryToHexString(buf));
            System.out.println(HexConvert.BinaryToHexString(buf));
            int port = recPacket.getPort();
            UdpClient.send(targetIp, port, new DoorSendMessage().getMessage());
            socket.close();
        } catch (Exception e) {
          
   
        } finally {
          
   
            //关闭socket
            socket.close();
        }
    }

}

创建客户端用于发送报文

import com.lanlinker.netty.paycard.util.HexConvert;
import lombok.extern.slf4j.Slf4j;

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

/**
 * @author aaron
 * @since 2021-01-27
 */
@Slf4j
public class UdpClient {
          
   

    public static void send(String ip, int port, byte[] content) {
          
   
        try {
          
   
            DatagramSocket socket = new DatagramSocket();
            SocketAddress socketAddress = new InetSocketAddress(ip, port);
            //参数1.数据 2.数据长度
            DatagramPacket packet = new DatagramPacket(content, content.length, socketAddress);
            String str = HexConvert.BinaryToHexString(content);
            log.info("目标IP:" + ip + ",目标端口:" + port + ",发送的报文:" + str);
            socket.send(packet);
            socket.close();
        } catch (IOException e) {
          
   
            e.printStackTrace();
        }
    }

}

将字节数组转换为16进制字符串的方法

//将字节数组转换为16进制字符串
    public static String BinaryToHexString(byte[] bytes) {
          
   
        String hexStr = "0123456789ABCDEF";
        String result = "";
        String hex = "";
        for (byte b : bytes) {
          
   
            hex = String.valueOf(hexStr.charAt((b & 0xF0) >> 4));
            hex += String.valueOf(hexStr.charAt(b & 0x0F));
            result += hex + " ";
        }
        return result;
    }

创建测试类

import com.lanlinker.netty.paycard.server.UdpClient;

/**
 * @author aaron
 * @since 2021-01-27
 */
public class Test {
          
   

    public static void main(String[] args){
          
   
        //16进制的 报文 数组
        byte[] message = new byte[1024];
        message[0] = (byte) 0x01;
        message[1] = (byte) 0x02;
        message[2] = (byte) 0x03;
        message[3] = (byte) 0x04;
        message[4] = (byte) 0x05;
        message[8] = (byte) 0x0E;
        UdpClient.send("127.0.0.1", 8800, message);
    }
}