import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
//主機一
class shanghai_Frame extends Frame implements Runnable,ActionListener{
     TextField out_message=new TextField("發(fā)數(shù)據(jù)到北京");	
	   TextArea in_message=new TextArea();
	   Button b=new Button("發(fā)數(shù)據(jù)到北京");
	   shanghai_Frame(){
	        super("我在上海");	
	   	    setSize(200,200);
	   	    setVisible(true);
	   	    b.addActionListener(this);
	   	    add(out_message,"South");
	   	    add(in_message,"Center");
	   	    add(b,"North");
	   	    Thread thread=new Thread(this);
	   	    thread.start();    //線程負責接收數(shù)據(jù)
	   }

	   //接收數(shù)據(jù)
	   public void run(){
	        DatagramPacket pack=null;
	        DatagramSocket mail_data=null;
	        byte data[]=new byte[8192];
	        try{
	             pack=new DatagramPacket(data,data.length);
	             //使用端口666來接收數(shù)據(jù)（因為北京發(fā)來的數(shù)據(jù)報的目標端口是666）
	             mail_data=new DatagramSocket(666);	        	
	        }catch(Exception e){}
	        while(true){
	             if(mail_data==null) 
	                  break;
	             else	
	        	        try{
	        	             mail_data.receive(pack);	
	        	        	   int length=pack.getLength();  //獲取收到的數(shù)據(jù)的實際長度
	        	        	   InetAddress adress=pack.getAddress();//獲取收到的數(shù)據(jù)的始發(fā)地址
	        	        	   int port=pack.getPort();//獲取收到的數(shù)據(jù)的始發(fā)端口
	        	        	   String message=new String(pack.getData(),0,length);
	        	        	   in_message.append("收到數(shù)據(jù)長度 "+length+"\n");
                                           in_message.append(""+adress+"端口 "+port+"\n");
	        	        	   in_message.append("收到數(shù)據(jù)是 "+message+"\n");
	        	        }catch(Exception e){}        	
	        }
	   }

	   //點擊按扭發(fā)送數(shù)據(jù)
	   public void actionPerformed(ActionEvent event){
	        byte buffer[]=out_message.getText().trim().getBytes();
	        try{
	        	   InetAddress address=InetAddress.getByName("localhost");
	        	   //數(shù)據(jù)的目標端口是888（那么接收方需要在這個端口接收）
	        	   DatagramPacket pack=new DatagramPacket(buffer,buffer.length,address,888);
	        	   DatagramSocket mail_data=new DatagramSocket();
	        	   in_message.append("數(shù)據(jù)報目標主機地址："+pack.getAddress()+"\n");
	        	   in_message.append("數(shù)據(jù)報目標端口是："+pack.getPort()+"\n");
	        	   in_message.append("數(shù)據(jù)報長度："+pack.getLength()+"\n");
	        	   mail_data.send(pack);
	        }catch(Exception e){}	
	   }
}

public class B地{
     public static void main(String arges[]){
          shanghai_Frame shanghai_win=new shanghai_Frame();	
     	    shanghai_win.addWindowListener(new WindowAdapter(){
     	         public void windowClosing(WindowEvent e){
     	              System.exit(0);	    
     	         }    	    	
     	    });
     	    shanghai_win.pack();
     }	
}