如何使用jruby（使用jetty运行）创建servlet？

I am pretty new to jruby and java and want to create a servlet in jruby while using jetty as web server. I am not sure if I am on the right way with the following code which shows the input form so far. I guess I have to extend now the HttpServlet class to handle the posted data but I don't know how to do this in this case and if it is okay to do this in the same script.I am pretty new to jruby and java and want to c