First thing that i can see is the action attribute in your jsp (Bear has already mentioned about it), it should be Login with context path as prefix to it,
Second thing is that youy are overriding the service method which should not be done ever. (unless you are left with no other option, which is rare). in this case, even if you reach your servlet, the doPost() method won't be called, only service() will be executed & an empty response will be returned.
Yes it can be done, we just have to figure out how.
Alas, poor Yorick, he knew this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop