简单了解Java的UDP编程

在UDPsend.java中，DatagramSocket ds = new DatagramSocket();在一个端口上创建，然后向3000端口发送消息，消息由DatagramPacket进行封装发送。 在UDPreceive.java中，在3000端口建立Datasocket，接收信息，根据getPort()方法得到发送来的信息的端口，再向该端口发送信息

public class UDPsend { public static void main(String...args) throws Exception{ String str = "hello world"; //向3000端口发送消息 DatagramSocket ds = new DatagramSocket(); DatagramPacket dp = new DatagramPacket(str.getBytes(),str.length(), InetAddress.getByName("127.0.0.1"),3000); System.out.println("我要发送"); ds.send(dp); Thread.sleep(1000); System.out.println("我要接受"); byte [] bt = new byte[1024]; DatagramPacket dpl = new DatagramPacket(bt,1024); ds.receive(dpl); System.out.println(new String(dpl.getData(),0,dpl.getLength())); } } import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; public class UDPreceive { public static void main(String...args) throws Exception{ DatagramSocket ds = new DatagramSocket(3000); byte [] bt = new byte[1024]; DatagramPacket dpl = new DatagramPacket(bt,1024); System.out.println("我要接受"); ds.receive(dpl); String str = new String(dpl.getData(),0,dpl.getLength()); System.out.println(str); Thread.sleep(1000); System.out.println("我要发送"); str+="22"; DatagramPacket dp = new DatagramPacket(str.getBytes(), str.length(), InetAddress.getByName("127.0.0.1"),dpl.getPort());//dp.getPort();得到端口 ds.send(dp); ds.close(); } }