Spring HandlerInterceptorAdapter - using to submit form when session times out. Can I

My users have been having a problem- they fill out a large form and sometimes their session times out before they complete it. If they submit the form, they are redirected to login page, and ultimately, all of the form data they entered is lost.

I use Spring 3, Spring Security 2 and have added a HandlerInterceptorAdapter to intercept the form submission. I'm trying to get the Form Model that was submitted so I can put it in the session and forward them back to the form after they've authenticated again. I want them to go back to the form and have it basically filled out with what they already entered.

I can get the parameter map from the HttpServletRequest, but this doesn't do me much good. I'm not going to rebuild the form model. I'm hoping there is a straight-forward way to get the form model in the interceptor "preHandle" method.