There is no "Service" method (with an upper case S).
So you haven't overridden any of the required methods needed to support a GET request.
Also, overriding the service method is not a good idea (except in rare cases). It is better to explicitly override doGet and doPost.
If you want the same code to handle both methods, have one call the other or have them both call a user defined method of your own.
public void Service(ServletRequest req,ServletResponse res) throws ServletException,IOException
this method must be:
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException
public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException