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.
Before we go too far on this I would like to make sure that we both understand what you need and the way JSP works. JSP code is run on the server, and typically used to dynamically generate HTML for web pages. The JSP code is run before the page is sent to the client browser, and so has no way it can read or write anything on the client system. Now, have I misunderstood your question? Is your JSP server actually running on what you call the "local computer", and you need to know how to build an HTTP request containing a local file to send to yet another server ?