Question

I’m trying to tracking valid user Ids in my Java servlet, can I implement HttpSessionListener this way ?

public class my_Servlet extends HttpServlet implements HttpSessionListener {   String User_Id;   static Vector<String> Valid_User_Id_Vector=new Vector<String>();   private static int activeSessions=0;    public void sessionCreated(HttpSessionEvent se)   { // associate User_Id with session Id; // add User_Id to Valid_User_Id_Vector     Out(' sessionCreated : '+se.getSession().getId());     activeSessions++;   }    public void sessionDestroyed(HttpSessionEvent se)   {     if (activeSessions>0)     { // remove User_Id from Valid_User_Id_Vector by identifing it's session Id       Out(' sessionDestroyed : '+se.getSession().getId());       activeSessions--;     }   }    public static int getActiveSessions()   {     return activeSessions;   }    public void init(ServletConfig config) throws ServletException   {   }    public void destroy()   {    }    protected void processRequest(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException   {     User_Id=request.getParameter('User_Id');   }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException   {     processRequest(request, response);   }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException   {     processRequest(request, response);   }    public String getServletInfo()   {     return 'Short description';   } } 

How to get the listener notified when a session ends ? I’m trying to bypass ‘/WEB-INF.web.xml’ all together, is it doable ? Or does it make sense ?

Answer 1

This won’t bypass /WEB-INF/web.xml. Furthermore, you’ll end up with 2 instances of this class, not 1 performing both functions. I suggest you put this Vector in the ServletContext and have 2 separate classes.

In the servlet, you get to it via getServletContext(). In the listener, you’ll do something like this:

public void sessionCreated(HttpSessionEvent se) {     Vector ids = (Vector) se.getSession().getServletContext().getAttribute('currentUserIds');     //manipulate ids }