fa.java

网络的停止等待ARQ的模拟

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
class Cl extends Frame implements ActionListener
{ 
  TextArea ta=new TextArea(5,10);
  TextField tf=new TextField(10);
  Socket c;
  double m;
  int i=0;
  int q=0;
  static int n;
  String ss="";
  static char abc[];
  DataInputStream in=null;
  DataOutputStream out=null;
  String s;
  double m1;
  public Cl()
  {
   super("发送方");
   s=null;
   setSize(250,250);
   tf.addActionListener(this);
   add("North",tf);
   add("Center",ta);
   addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}});
   show();
   
   } 
  public void actionPerformed(ActionEvent e)
  {
	  if(e.getSource()==tf)
	  {
		  String sss=tf.getText();
		  abc=sss.toCharArray();
		  try
		  {
			  c=new Socket("200.200.202.58",8888);
			  in=new DataInputStream(c.getInputStream());
			  out=new DataOutputStream(c.getOutputStream());
			  while(true)
			  {
				  n=0;
				  m=Math.random()*100;
				  m1=Math.random()*100;
				  if((m1>=0)&&(m1<50))
				  {
				   q=1;
				  }
				  else
				  {
				   q=0;
				  }
				  ss=String.valueOf(abc[i]);
				  String ss1=String.valueOf(q);
				  ss1=ss1.concat(" ");
				  ss1=ss1.concat(ss);
				  ta.append("发送:"+ss1);
				  ta.append("\n");
				  if(m>20&&m<=100)
				  {
					  out.writeUTF(ss1);
					  ss1="";
				  }
				  System.out.println("启动超时计时器:");
				  for(int zz=0;zz<3;zz++)
				  {System.out.println(n++);
				   Thread.sleep(1000);
					  if(m>20&&m<=100)
					  {
						  break;
            
					  }
					  }
				  if(n==3)
				  {   
					  ta.append("超时重发");
					  ta.append("\n");
					  continue;
				  }
				  while(true)
				  {
					  s=in.readUTF();
					  if(s.equals("ack"))
					  {
						  ta.append("发送正确继续发"+"\n");
						  i=i+1;
						  break;		
					  }
					  if(s.equals("nak"))
					  {
						  ta.append("发送错误重新发"+"\n");
						  break;
					  }
				  }
				  if(i==abc.length){break;}
			  }
		  }
		  catch(InterruptedException e1){}
		  catch(IOException e2){}
	  }
    }	
}
public class fa
{
	public static void main(String args[])
	{
		new Cl();
	}
}