java实现简易局域网聊天功能

/* 
使用UDP模式,编写一个聊天程序 
有发送和接收数据2部分, 
一个线程接收,一个线程发送 
 
由于发送和接收动作是不一致的,所以要使用2个run方法 
而且这两个方法要封装到不同的类中 
 
本程序忽略了部分异常的处理,也未加入UI组件 
这样比较简洁 
 
发送端口9998 
接受端口9999 
用的是局域网广播地址,所以自己发的消息自己也收到了 
 
[示例]:简易控制台聊天程序 
*/ 
import java.net.*; 
import java.io.*; 
class Demo 
{ 
 public static void main(String[] args) throws Exception 
 { 
  DatagramSocket sendSocket = new DatagramSocket(9998); //发送端 
  DatagramSocket receSocket = new DatagramSocket(9999); //接收端 
  new Thread(new MsgSend(sendSocket)).start();      //发送线程 
  new Thread(new MsgRece(receSocket)).start();      //接受线程 
 } 
} 
 
class MsgSend implements Runnable   //发送 
{ 
 private DatagramSocket dsock; 
 public MsgSend(DatagramSocket dsock) 
 { 
  this.dsock= dsock; 
 } 
 
 public void run() 
 { 
  BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in)); 
  String lineStr = null; 
  try 
  {     
   while(true) 
   { 
    lineStr = bufr.readLine(); 
    if(lineStr!=null) 
    { 
     if(lineStr.equals("over886")) 
     { 
      break; 
     } 
     else 
     { 
      byte[] dataBuf = lineStr.getBytes(); 
      DatagramPacket dataPack =  //数据打包 
      new DatagramPacket( dataBuf, 
                dataBuf.length, 
                InetAddress.getByName("192.168.1.255"), //广播 
                9999 //目标端口 
               ); 
      dsock.send(dataPack); 
     } 
    } 
   } 
   bufr.close(); 
   dsock.close(); 
  } 
  catch(Exception e) 
  { 
   throw new RuntimeException("发送失败!"); 
  } 
 } 
} 
 
class MsgRece implements Runnable  //接收 
{ 
 private DatagramSocket dsock; 
 public MsgRece(DatagramSocket dsock) 
 { 
  this.dsock= dsock; 
 } 
 
 public void run() 
 { 
  try 
  { 
   while(true) 
   { 
     byte[] dataBuf = new byte[1024]; 
     DatagramPacket dataPack = new DatagramPacket(dataBuf,dataBuf.length); 
     dsock.receive(dataPack); //将获取的数据保存到指定的数据包 
     String ip = dataPack.getAddress().getHostAddress(); 
     String data = new String(dataPack.getData(),0,dataPack.getLength()); 
     int port = dataPack.getPort(); 
     System.out.println();  
     System.out.println("来自ip为 "+ip+" <对方端口>: "+port+" 的消息"); 
     System.out.println(data);     
   } 
  } 
  catch(Exception e) 
  { 
   throw new RuntimeException("接受失败!"); 
  } 
  finally 
  { 
   dsock.close(); 
  } 
 } 
}