You may include one XML file into another by using XML entities. I never tried this before on web.xml, but why shouldn't it work with it - after all this is an XML feature. For example, let this will be a content of "resources.xml" file (it should be available for the server's parser, thus better to put it in the same directory where your web.xml is)
And you want to include it into your web.xml. It works like this:
I tried this out on my application - it works fine indeed. Hope this helps you.