UDP 用户数据报文协议的发送和接收示例

UDP是基于数据报文的传输协议，面向无连接，不可靠，下面介绍发送和接收的Demo：
发送程序：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.nio.channels.DatagramChannel;

public class UDPSendDemo {
    public static void main(String[] args) {
        try {
        //绑定端口，通过18651端口进行发送，也可以不绑定(有系统随机分配端口)
            DatagramSocket ds = new DatagramSocket(18651);
            DatagramPacket send = null;
            try {
            //获取键盘输入数据
                BufferedReader input = new BufferedReader(
                new InputStreamReader(System.in,"UTF-8"));
                String buf = null;
                try {
                //检测到回车时，进行数据读取
                    while((buf = input.readLine())!=null){
                    //将字符串转换成字节数组
                        byte[] b = buf.getBytes("UTF-8");
                        //进行数据包封装，包含数据内容，长度，目的地址和目的端口
                        send = new DatagramPacket(
                        b,b.length,InetAddress.getLocalHost(),18650);
                        //发送
                        ds.send(send);
                        System.out.println("Send OK!");
                        if(buf.equals("886"))
                            break;
                    }
                    //关闭UDP
                    ds.close();
                    //关闭输入流
                    input.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            } catch (UnsupportedEncodingException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

---

接收程序：

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

public class UDPReceiveDemo {
    public static void main(String[] args) {
        try {
        //绑定端口，接收此端口收到的数据，这里一般是都要绑定的，不然有点傻X
            DatagramSocket ds = new DatagramSocket(18651);
            //定义接收缓冲区大小1024
            byte[] buf = new byte[1024];
            DatagramPacket rec = new DatagramPacket(buf,buf.length);
            while(true){
                try {
                //在此等待外来数据
                    ds.receive(rec);
                    String msg = new String(rec.getData(),0,rec.getLength());
                    if(msg.equals("886")){
                        break;
                    }
                    String ip = rec.getAddress().getHostAddress();
                    int port = rec.getPort();
                    System.out.println(msg+" "+ip+":"+port);
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            ds.close();
        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}