jieshou.java

这是一个接收数据报程序,与发送数据报的工能相反,当另一台机器用发送数据报程序发送数据报,则它可收到该数据报.

package je3.net;
import java.io.*;
import java.net.*;
//import java.awt.*;
//import java.applet.*;

 class UDPReceive{
	  public static final String usage="Usage:jva UDPReceive <port>";
	  public static void main(String[] args)
	  {try{ 
	        if(args.length!=1)
	  	    throw new IllegalArgumentException("Wrong number of args");
	  	    int port =Integer.parseInt(args[0]);
	  	    DatagramSocket dsocket=new DatagramSocket(port);
	  	    byte[] buffer=new byte [2048];
	  	    DatagramPacket packet=new DatagramPacket(buffer,buffer.length);
	  	    for(;;){
	  	    dsocket.receive(packet);
	  	    String msg=new String(buffer, 0, packet.getLength(), "UTF-8");
	  	    System.out.println(packet.getAddress().getHostName()+":"+msg);
	  	    packet.setLength(buffer.length);
	  	}
	  	
	  	
	  	}
	catch (Exception e){
		System.err.println(e);
		System.err.println(usage);
		}
	}
}