简单的autosave for Spring MVC窗体

I have one page form done with Spring MVC. User has to register first and I would like the form to be saved automatically so user can come later to finalize it. Traditional form submission with a timer is not what I'm looking for. Instead, I am planning to use some ajaxy way to send fields to the server at each onFocus event.I have one page form done with Spring MVC. User