UDP传输数据

DatagramSocket：通讯的数据管道
常用方法：send（发送）和receive（接收）
绑定一个IP和Port（可选多网卡）
DatagramPacket：封装数据
地址标签：目的地IP+Port
UdpRecv.java

public class UdpRecv {
    public static void main(String[] args) throws Exception {
        DatagramSocket dr = new DatagramSocket(3000);
        byte[] buf = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf,1024);
        System.out.println("我在等待消息");
        dr.receive(dp);
        System.out.println("我已接收到消息");
        String strRecv = new String(dp.getData(),0, dp.getLength())+
                "from"+dp.getAddress().getHostAddress()+"："+dp.getPort();
        System.out.println(strRecv);
        System.out.println("我要开始发送消息了");
        String str = new String("你好，UDP");
        DatagramPacket dp2 = new DatagramPacket(str.getBytes(StandardCharsets.UTF_8),
                str.length(), InetAddress.getByName("127.0.0.1"),dp.getPort());
        dr.send(dp);
        System.out.println("发送消息结束了");
    }
}

UdpSend.java

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.charset.StandardCharsets;

public class UdpSend {
    public static void main(String[] args) throws Exception {
        DatagramSocket ds = new DatagramSocket();
        String str = "Hello UDP";
        DatagramPacket dp = new DatagramPacket(str.getBytes(StandardCharsets.UTF_8),
                str.length(), InetAddress.getByName("127.0.0.1"),3000);
        System.out.println("我要发送数据了");
        ds.send(dp);
        System.out.println("我发送数据结束了");
        Thread.sleep(1000);
        byte[] buf = new byte[1024];
        DatagramPacket dp2 = new DatagramPacket(buf,1024);
        System.out.println("我开始接收数据了");
        ds.receive(dp2);
        System.out.println("我接受结束结束了");
        String str2 = new String(dp.getData(),0,dp2.getLength())+
                "fron"+dp.getAddress().getHostAddress()+"："+dp.getPort();
        System.out.println(str2);
    }
}