This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I think you should be able to pull that information from the Referer header of the request, try: request.getHeader("Referer"); It should give you the URL that you just came from (e.g. your servlet). Depending on what you are doing with it, you may have to parse the string or check only the last part of it. Hope this helps.
Referer won't necessarily identify the forwarding servlet; it will report what the brwser decided to put into the header. Especially if the request has been forwarded around a bit, this may or may not be useful. My question is: why would you want to do this? Passing info forward (via attributes) is a much more conventional and architecturally pure mechanism. Back-tracking in order to affect behavior muddies the architectural picture and introduces coupling where none is needed.