One way of giving the *illusion* that you are showing Swing components in a browser is to use WebCream, a product marketed by Cream Tec:
http://www.creamtec.com/webcream
This allows you to run a Swing app on your server and it converts the GUI to HTML/DHTML and sends it to the client - so the client gets something that looks similar to your Swing GUI, but made from HTML + JavaScript. Don't forget - the code is not running on the client's machine, so response will be slower...
I've never tried WebCream, but it looks intersting.