如何判断浏览器的请求头是不是结束

\r\n\r\n好像是结束符

package com.maple.detail3;
 
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.net.ServerSocket;
 import java.net.Socket;
 
 public class TcpServer3 {
     public static void main(String[] args) throws Exception {
 
         ServerSocket serverSocket=new ServerSocket(10000);
         Thread t=null;
         while(true)
         {
             Socket socket=serverSocket.accept();
              t=new Thread(new ReadPic(socket));
              t.start();
         }
     }
 
 }
 
 class ReadPic implements Runnable
 {
     Socket socket=null;
     
     public ReadPic(Socket socket) {
         this.socket=socket;
     }
 
     @Override
     public void run() {
         try {
             OutputStream outputStream=socket.getOutputStream();
             InputStream inputStream=new FileInputStream("c:/2.png");
             
             InputStream socketInputStream=socket.getInputStream();
             
             
             byte[] buf=new byte[1024];
             int len=0;
             
             while((len=socketInputStream.read(buf))!=-1)
             {
                 String line=new String(buf,0,len);
                 System.out.println(line.length()+"  "+line);
                 if(line.endsWith("\r\n\r\n"))
                 {
                     System.out.println("game is over");
                     break;
                 }
             }            
             System.out.println("kkkkkkkkkkkkkkkk");
             while((len=inputStream.read(buf))!=-1)
             {
                 outputStream.write(buf,0,len);
                 outputStream.flush();
             }
             socket.close();
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }