//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