I have a portlet which involves displaying several JSP pages. 

In first JSP `page A`, when I click the Submit button on `Page A` the `processAction()` method takes action and a JSP `page B` appears. 

Now if I use Web Browser's **Back button** to `page A` and click the Submit button again, the
JSP `page B` appears but I noticed the `processAction()` didn't take any action. (Usually clicking Submit button in a JSP page can result in the `processAction()` to take action).

Can anyone help for this problem? In my Porlet, it MUST go to the process action but it doesn't after back button.