Files download webpages controlled by Java; detail pages are different but download links the same

I am trying to automate the download process of files from webpages. There’s no direct link to the files. It seems like they are only generated once an option is chosen.

The webpage show the product details. And on the pages, there’s a bottom (pop-up, Java control) that user can choose to export the details to either “.xls” or “.pdf” files.

Like product ID “LYK89652”, the product page is: http://ift.tt/29Ztojb

However the links that generate the files are always the same, no matter how the product ID is changed: http://ift.tt/2abPq5N

If I try to open this link directly, there won’t be any files downloaded.

What would be the techniques to find out the actual download links (or the ways to explore)?

Many thanks.

(It’s a company’s internal web so please excuse me not to disclose the full link.)