Method to recognise the device from where request is coming

A want to design a web application which can receive request from multiple devices such as from a pc through browser,from a mobile phone etc,how can i know that from which device request is coming so that i can generate the specific response for that device means for browser generate html ,for mobile phone generate wml etc.
I check the methods of class ServletRequest as well as HttpServletRequest to know but unable to find a method.Anybody can plz let me know whats the method i should use and that method belongs to which class.

What about HttpServletRequest.getHeader() and look for User-Agent -- I'm pretty sure it will tell you what kind of device the user is accessing your site with (whether it be IE, a Nokia or Sony Clie).