import java.io.*;
import java.net.*;
class Send implements Runnable
{
private DatagramSocket ds;
public Send(DatagramSocket ds)
{
  this.ds=ds;
}
public void run()
{
  try
  {
   BufferedReader bufr=new BufferedReader(new InputStreamReader(System.in));
   String line=null;
   while ((line=bufr.readLine())!=null)
   {
    if ("888".equals(line))
    {
     break;
    }
    byte[] buf=line.getBytes();
    DatagramPacket da=new DatagramPacket(buf,buf.length,InetAddress.getByName("192.168.1.101"),30002);
    ds.send(da);
   }
   ds.close();
  }
  catch (Exception e)
  {
   throw new RuntimeException("发送端异常！请注意！");
  }
}
}
class Rece implements Runnable
{
private DatagramSocket ds;
public Rece(DatagramSocket ds)
{
  this.ds=ds;
}
public void run()
{ try
  {
   while(true)
   {
    byte[] buf=new byte[1024];
    DatagramPacket dp=new DatagramPacket(buf,buf.length);
    ds.receive(dp);
    String data=new String(dp.getData(),0,dp.getLength());
    String ip=dp.getAddress().getHostAddress();
    System.out.println("ip="+ip+"-----"+"data="+data);
   }
  }
  catch (Exception e)
  {
   throw new RuntimeException("接收端异常！请注意！");
  }
}
}

public class  UdpDemo3
{
public static void main(String[] args) throws Exception
{
  DatagramSocket sendsocket=new DatagramSocket();
  DatagramSocket recisocket=new DatagramSocket(30001);
  new Thread(new Send(sendsocket)).start();
  new Thread(new Rece(recisocket)).start();
}
}



在Dos窗口中执行完一次再次执行时为什么总是提示地址在使用中？

应该是端口还没释放

接收没有关闭资源。接收端口没被释放。