JSP Session

Hi,

I need help with JSP session.

My problem:
I have a login page. When a user logs in then, i set a session and its expiration time. So, when the session is expired, the user will be redirected to the login page with a session expired message.
I want to identify if a page has been loaded first time by the user, or it has been loaded as a result of expiration of session.

My code:

I do the following when the user successfully logs in:

Code:

session.setAttribute("username",user_id);
session.setMaxInactiveInterval(600);

I check this in every page (i.e. check in the header of everypage)

Code:

String username = (String) session.getAttribute("username");
 
if (session.isNew() == true && username == "")
{
    response.sendRedirect("login.jsp?rtype=expired");
}
else
{
    //check the credentials
}

Also when the user logs out the following code is executed:

Code:

session.invalidate();

My problem is that even when the user comes to the page for first time, it redirects the user to "login.jsp?rtype=expired" page.