Most Java parsers offer some such functionality, though details vary.
For example, you could use a SAX parser and ignore DocumentHandler.element
callbacks for the elements you're not concerned with.
Sun's package, as well as others, support this. I think it's more typical
that folk want to add special processing for specific tags, rather than
ignore the others. In Sun's package you can define particular "XML Beans"
to represent those tags, and customize processing in that way. To do that,
you "register" element classes, which can have your custom code. Similar
mechanisms exist in a number of other packages, and some standards will
probably be forthcoming in this area.
- Dave