ShowSession.java  Servlet that uses session tracking to determine if the client is a repeat visitor. Uses the ServletUtilities  class to simplify the DOCTYPE and HEAD output.


package cwp;

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

/** Simple example of session tracking.
 *

* Taken from Core Web Programming Java 2 Edition * from Prentice Hall and Sun Microsystems Press, * . * May be freely used or adapted. */ public class ShowSession extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Session Tracking Example"; HttpSession session = request.getSession(true); String heading; Integer accessCount = (Integer)session.getAttribute("accessCount"); if (accessCount == null) { accessCount = new Integer(0); heading = "Welcome, Newcomer"; } else { heading = "Welcome Back"; accessCount = new Integer(accessCount.intValue() + 1); } // Use setAttribute instead of putValue in version 2.2. session.setAttribute("accessCount", accessCount); out.println(ServletUtilities.headWithTitle(title) + "\n" + "

" + heading + "

\n" +
                "

Information on Your Session:

\n" +
                "\n" +
                "\n" +
                "  \n" +
                "  \n" +
                "  \n" +
                "  \n" +
                "

\n" +
                "");

  }

  /** Handle GET and POST requests identically. */

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