java UDP通信客户端与服务器端实例分析

import java.net.*;
public class TestUdpServer {
    public static void main(String[] args) throws Exception {
        byte[] buf = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf,buf.length);
//        try {
            DatagramSocket ds = new DatagramSocket(2345);
            while(true) {
                ds.receive(dp);
                System.out.println(new String(buf,0,dp.getLength()));    
//            }
//        } catch (Exception e) {
//            e.printStackTrace();
        }
    }
}

import java.net.*;
public class TestUdpClient {
    public static void main(String[] args) throws Exception {
        byte[] buf = new byte[1024];
        buf = (new String("hello")).getBytes();
        DatagramPacket dp = new DatagramPacket(buf,buf.length,new InetSocketAddress("127.0.0.1",2345));
//        try {
            DatagramSocket ds = new DatagramSocket(5679);
            ds.send(dp);
            ds.close();
//        } catch (Exception e) {
//            e.printStackTrace();
//        }
    }
}

import java.io.*;
import java.net.*;
public class UdpServer {
    public static void main(String[] args) throws Exception {
        byte[] buf = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf,buf.length);
        DatagramSocket ds = new DatagramSocket(2345);
        while(true) {
            ByteArrayInputStream is = new ByteArrayInputStream(buf);
            DataInputStream dis = new DataInputStream(is);
            ds.receive(dp);
            System.out.println(dis.readLong());    
        }
    }
}

import java.io.*;
import java.net.*;
public class UdpClient {
    public static void main(String[] args) throws Exception {
        Long n = 10000L;
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(os);
        dos.writeLong(n);
        byte[] buf = new byte[1024];
        buf = os.toByteArray();
        System.out.println(buf.length);
        DatagramPacket dp = new DatagramPacket(buf,buf.length,
                new InetSocketAddress("127.0.0.1",2345));
        DatagramSocket ds = new DatagramSocket(5679);
        ds.send(dp);
        ds.close();
    }
}