Anything a servlet can do, a JSP can do as well. You know why? A jsp IS a servlet. The first time a JSP is executed it is translated into a servlet. Requests are handled in the same way: only a JSP will handle a GET or POST like they are the same thing.
Why would you want to use a JSP however? A servlet is better suited for such program logic, a JSP should be limited to the presentation part of a request only.