import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

public class ExampleServlet extends HttpServlet {

    

    /** Processes requests for both HTTP GET and POST methods.

     * @param request servlet request

     * @param response servlet response

     */

    protected void service(HttpServletRequest request, HttpServletResponse response)

    throws ServletException, IOException {

        

        response.setContentType("text/html;charset=UTF-8");

        PrintWriter out = response.getWriter();

        

        printPageStart(out);

        

        //Obtain the session object, create a new session if doesn't exist

        HttpSession session = request.getSession(true);

        

        //Check if our session variable is set, if so, get the session variable value

        //which is an Integer object, and add one to the value.

        //If the value is not set, create an Integer object with the default value 1.

        //Add the variable to the session overwriting any possible present values.

        Integer param = (Integer) session.getAttribute("MySessionVariable");

        if (param != null) {

            

            session.setAttribute("MySessionVariable", new Integer(param.intValue() + 1));

            param = (Integer) session.getAttribute("MySessionVariable");

            

        } else {

            

            param = new Integer(1);

            session.setAttribute("MySessionVariable", param);

            

        }

        

        out.println("You have displayed this page " + param.intValue() + " times this session.

");

        out.println("Hit the browsers refresh button.");

        

        printPageEnd(out);

    }

    

    /** Prints out the start of the html page

     * @param out the PrintWriter object

     */

    private void printPageStart(PrintWriter out) {

        

        out.println("");

        out.println("");

        out.println("");

        out.println("");

        out.println("");

        

    }

    

    /** Prints out the end of the html page

     * @param out the PrintWriter object

     */

    private void printPageEnd(PrintWriter out) {

        

        out.println("");

        out.println("");

        out.close();

    }

}

 

This is what the text will look like if you hit the refresh button a few times:

You have displayed this page 16 times this session.

Hit the browsers refresh button.