HTML/JSP switch

Hallo /comp/!

I have been searching for a method in wich a server sends the content of a website to a PC in HTML and the same content of that website to smartphones in JSP.

What are the posibilities? is there a way so that server can know where the requested URL was made from? (eg: PC, laptop, tablet, phone)

Thanks for your suggestions!

use php to check the user agent of the browser, firefox for smartphone etc