//ShowTimesServlet.java /*Servlet实现访问次数的例子!*/
import java.io.*;
import java.util.zip.*;
import javax.servlet.*;
import javax.servlet.http.*;
/*
 这个类实现访问次数。显示访问次数！看是第几次访问！
*/
public class ShowTimesServlet extends HttpServlet {

 public void doGet(HttpServletRequest request,HttpServletResponse response)
               throws ServletException, java.io.IOException {

            response.setContentType("text/html");
   Httpsession session = request.getSession();
   String heading;
   Integer accessCount =(Integer)session.getAttribute("accessCount");
   if(accessCount == null) {
    accessCount = new Integer(0);
    heading = "Welcom,You are first time to visit!";
   }
   else {
    heading = "Welcome Backer";
    accessCount = new Integer(accessCount.intValue()+1);
   }
      session.setAttribute("accessCount",accessCount);
   PRintWriter out = response.getWriter();
   out.println("The title:"+heading);
   out.println("Access count: "+accessCount);
 }

 public void doPost(HttpServletRequest request,HttpServletResponse response)
               throws ServletException, java.io.IOException {
  doGet(request,response);
 }

}

http://blog.csdn.net/laiahu/archive/2007/01/23/1491695.aspx