java模拟聊天

package randomAccessFile;

import java.io.IOException;
import java.io.PipedReader;

//消息接收端
class Receive
{
  static PipedReader pr;
  static Send s;
  public Receive() {
    
  }
  public Receive(Send s)
  {
    this.s=s;
  }
  public Receive(PipedReader pr,Send s)
  {
    super();
    this.pr = pr;
    this.s=s;
  }
  public static String recevie() throws IOException//接收消息
  {
    String l="";
    char ch='\0';
    while((ch=(char)pr.read())!='?')
    {
      l+=ch;
    }
    int length=Integer.parseInt(l);
    char [] message=new char[length];
    pr.read(message);
    if(pr!=null)
    {
    // pr.close();
    }
    String m=new String(message);
    System.out.println("收到消息:"+m);
    if(m.equals("88"))
    {
      System.out.println("聊天结束!");
      //关闭流
      System.exit(0);
    }
    //继续通知发送
    else
    {
      s.send();
     
    }
    return m;
  }
  
}

package randomAccessFile;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PipedWriter;

//消息发送端
class Send 
{
    PipedWriter pw;
    Receive rec;
    public Send(PipedWriter pw)
    {
        this.pw=pw;
    }
    public Send(PipedWriter pw,Receive rec)
    {
        super();
        this.pw = pw;
        this.rec=rec;
        
    }
    public void send() throws IOException
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String message="";
        String messageTest="";
        do
        {
            System.out.println("请输入你要发的消息:");
            message=br.readLine();
            messageTest=message.trim();//去掉左边空格
            if(messageTest.length()==0)
            {
                System.out.println("不能发送空消息");
            }
            
        }
        while(messageTest.equals(""));
        System.out.println("你发送的内容是:"+message);
        pw.write(message.length()+"?"+message);
        //通知接收
        rec=new Receive();
        rec.recevie();
        
    }

}

package randomAccessFile;
import java.io.*;
public class Test
{
  public static void main(String[] args) throws IOException 
  {
    
    PipedWriter pw=new PipedWriter();
    PipedReader pr=new PipedReader();
    Send s=new Send(pw);
    Receive r=new Receive(pr,s);
    pr.connect(pw);
    boolean a=true;
    try
    {
      while(a)
      {
       s.send();
       r.recevie();
      }
    } 
    catch (IOException e)
    {      
      e.printStackTrace();
    }
      if(pw!=null)
      {
        pw=null;
      }
      if(pr!=null)
      {
        pr=null;
      }
    
  
  }
}