Java Web Application Attachments list

I'm working on a Java web application, in a web page there is a listbox field in which some PDF attachments links are listed, when clicking a link; saving window appears asking the user if she wants to open the PDF file or to save it, I want to develop a feature that allows The user to modify the PDF file and saves it. The PDF will automatically close and go back to my application, so when the user opens this attachment by clicking on its link again, it will be updated. Is there any way that you could provide ? Thanks..