Simple Session Tracking

Servlets in More Detail example from a Well House Consultants training course
More on Servlets in More Detail [link]

This example is described in the following article(s):
   • Sharing the load between servers - httpd and Tomcat - [link]
   • Load balancing with sticky sessions (httpd / Tomcat) - [link]
   • Clustering on Tomcat - [link]
   • Distributing the server load - yet ensuring that each user return to the same system (Apache httpd and Tomcat) - [link]
   • Java web application for teaching - now with sessions and clustering / load balancing demonstrations - [link]

Source code: Barman.java Module: J906

import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
* Simple Session Tracking
*/
public class Barman extends HttpServlet {

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

        HttpSession session = request.getSession(true);
        Integer count = (Integer)session.getAttribute("mycounter");
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<body bgcolor=\"#FFAACC\">");

        if (count == null) {
                count = new Integer(0);
                out.print("<h1>Welcome to the 'Lilac Tree'. Please enter your name</h1>");
                out.print("<form>");
                out.print("<input name=whoyouare>");
                out.print("</form>");
        } else {
                String wanted = request.getParameter("whoyouare");
                if (wanted != null) {
                        session.setAttribute("who",wanted);
                } else {
                        wanted = (String)session.getAttribute("who");
                }
                count = new Integer(count.intValue() + 1);
                out.print("<h1>Welcome back "+wanted+"</h1>");
                out.println("This is your visit no. "+count+"<br>");
        }
        session.setAttribute("mycounter",count);
        out.println("</body>");
        out.println("</html>");
    }
}

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* Learning to Program in Java
* Java Bootcamp
* Java Programming for the Web
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