It's not completely cleare for me what you are tryin to say. Do you want to map URL's to certain controllers? Or do you want to implement your own servlet?

In the first case: Use the web.xml to define the servlet and map it to an URL pattern like *.htm. When this matches, the application server will use the [yourservletname]-servlet.xml to match a certain URL pattern to a controller.

In the second case: use the first case to understand the construct. Then use google to find out how a servlet works. I'm not quite sure because I always use the default one that comes with Spring.