java:用UDP协议，开发一个聊天工具代码

/**
用UDP协议，开发一个聊天工具
*/

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

//发送端
class SendChat implements Runnable
{
private DatagramSocket sendSocket;
public SendChat(DatagramSocket sendSocket)
{
this.sendSocket = sendSocket;
}
public void run()
{
try
{
//键盘录入
BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));

String line = null;
while((line = bufr.readLine()) != null)
{
if("over". equals(line))
{
break;
}
//确定数据，并封装成包
byte[] buf = line.getBytes();

DatagramPacket dp = new DatagramPacket(buf, 0, buf.length, InetAddress.getByName("10.22.72.144"), 30002);

sendSocket.send(dp);
}

sendSocket.close();
}
catch(Exception e)
{
throw new RuntimeException("发送失败");
}
}
}

//接收端
class RecChat implements Runnable
{
private DatagramSocket recSocket;
public RecChat(DatagramSocket recSocket)
{
this.recSocket = recSocket;
}
public void run()
{
//定义数据包，用于存储数据
byte[] buf = new byte[1024];
while(true)
{
try
{
DatagramPacket dp = new DatagramPacket(buf, buf.length);

//接收数据
recSocket.receive(dp);

//获取数据包中的数据
String ip = dp.getAddress().getHostAddress();
String data = new String(dp.getData(), 0, dp.getLength());

System.out.println(ip +":" +data);
}
catch(Exception e)
{
throw new RuntimeException("接收失败");
}
}
}
}

class Chat
{
public static void main(String[] args) throws Exception
{
DatagramSocket sendSocket = new DatagramSocket();
DatagramSocket recSocket = new DatagramSocket(30002);

new Thread(new SendChat(sendSocket)).start();
new Thread(new RecChat(recSocket)).start();
}
}