I have a few comments which I hope will be helpful.
Your indentation makes the code harder to follow.
Who do you think will use the non-zero-arg constructors? The Servlet class is going to be instantiated by the container, using the zero-arg constructor - and it must be this way. In other words, you can just go and create one yourself (using new Simple(...) for example). (later edit: I see where they are used now and will comment on that below...).
In your zero-arg constructor, you're not calling the super's constructor:
In your
doPost() method, you're creating an instance of the Servlet?!?
No, no, no, no...
You're using the Servlet class as though it were a JavaBeans class (at least that what it's looks like you're trying to do). If you wish to use a JavaBeans object, create a separate class for that. In fact, it looks like you're creating a completely separate Simple instance for each variable. I just can't imaging what you're thinking there
The error you say you're getting is usually due to writing some response to the client, then trying to forward. Although I don't see you doing that here, with all the noise in that code, it's rather hard to tell.
Why are you catching any exceptions in the
doGet() method? Don't do that. Just call
doPost(request, response); and be done with it.
First things first - follow a tutorial on Servlets and JSP. Get a good understanding of how they work, how you pass data around between the servlet class and the JSP page, etc. Ignore the database work for now. Come back to that once you have a better handle on Servlets and JSP in general.
Best of luck. Please go through a tutorial. If you learned what you're doing in your example from a tutorial, find a better tutorial
Edit: Ahh, yes. As Ben said, you're forwarding within the while loop, and so trying to forward multiple times. This is not the way to do it.