Please help to explain how the servlet code work?
From the code I saw it just check the session, if user click at back button isn't that the session still valid and they still able to re-submit the form again?
I've try the code on my workflow application, I've done the submit but the server output stated the session is valid no redirect require, so no matter how many times I submit the form is possible. Due to it is workflow application, it require user to login before hand so the session is valid till they logout. So for my case how to prevent user to submit twice??