statefull visitor counter

 import java.io.IOException;  
 import java.io.PrintWriter;  
 import javax.servlet.http.HttpServlet;  
 import javax.servlet.http.HttpServletRequest;  
 import javax.servlet.http.HttpServletResponse;  
 import javax.servlet.http.HttpSession;  
 public class counter extends HttpServlet  
 {  
   @Override  
   public void doGet(HttpServletRequest req,HttpServletResponse res) throws IOException  
   {  
     HttpSession session=req.getSession(true);  
     Integer count=(Integer)session.getAttribute("count");  
     if(count==null)  
     {  
       count=1;  
     }  
     else  
     {  
       count=new Integer(count.intValue()+1);  
     }  
     session.setAttribute("count", count);  
     PrintWriter pw=res.getWriter();  
     pw.println("counter is="+count);  
   }  
 }