How to check if session exists?

[H Melua]

Hello

I've written this code which (i honestly know) is completely inefficient , but anyway... i'm trying to use sessions to determine whether a user is logged in or out... but my super inefficient code isn't doing what i want

here it is..

//first i want it to check if there is an existing session
if ((request.getSession(false)==null) 
    && (request.getParameter("username")== null 
    && request.getParameter("password") == null)) {%>
     //then print out a HTML form to login
 
//if the session exists then allow the user to log off
}else if(request.getSession(false)!= null){
    Object username = (session.getAttribute("name"));
    out.println(username + " is logged in!");
    %> <a href="login.jsp?logoff=true">Log off</a> <%
 
//else if the user has clicked on logoff then
}else if(request.getParameter("logoff") != null){
    session.removeAttribute("username");
    session.invalidate();
    response.sendRedirect("login.jsp");
 
//else if the details have been given then create the session
}else if (request.getParameter("username") != null 
       && request.getParameter("password") != null){
    String username = request.getParameter("username");
    session = request.getSession(true);
    session.setAttribute("name", request.getParameter("username"));
    session.setMaxInactiveInterval(-1);
}%>

Problem:
When i click on the logoff link, it takes me back to the same option to logoff! and thus it is not recognising that the object has been invalidated when the link was clicked! (although i've tested it to see if it is executing the logoff else statement and it was!)
and so if the session has indeed been invalidated, should itbe executing this else statement

}else if(request.getSession(false)!= null){

Thanks for trying really hard to understand my code
HannaH
[ December 03, 2007: Message edited by: H Melua ]

[Ben Souther]

I've found it's a lot simpler to test for the existence of an object bound to session than to test for the session itself.

 
if(null == session.getAttribute("name")){
  // User is not logged in.
}else{
  // User IS logged in.
}

JSPs, by default, create a session so I just assume that there is one and only use getSession() (no arguments) to obtain a reference to it.


Also, these days, it is recommended that this type of logic be factored back into a plain old Java object and controlled from a servlet. Life gets easier once you've moved all of your logic out of the JSPs.
[ December 03, 2007: Message edited by: Ben Souther ]

[H Melua]

:shocked: :shocked: :shocked:

oh my goodness!!! that workssssss

I should've asked days ago!!!

Thank you "VERY" much, that really drove me nuts!! I thought if i do it this way after i've invalidated the session, it will throw an exception!

Some kind 1 in this forum has advised me to use servlets before, but i'm not getting time to read about them, the course i'm doing is really intensive!!

oh well, life is dragging, and again
thank you very much.................
HannaH
[ December 03, 2007: Message edited by: H Melua ]

[Nguyen Duy Lam]

thanks for this post, it working now...
I was looking for a long time..nice job