Again, Apache has an XML solution ready for use. Called Xerces, it contains the basic classes you'll need to parse XML. It's a widely used package and, in fact, is the one used inside Tomcat itself.
To install Xerces, you only need to download a Xerces distribution from http://xml.apache.org/dist/xerces-j/. As of this writing, the 2.0 release was still in beta, so the examples in this chapter use release 1.4.4.
The distributions come as ZIP files. Unpack the file in a temporary directory, look for it in the top-level directory called xerces.jar, and copy it to your TOMCAT/lib directory. You've now installed XML support. The next step is to do something with it.