You might check out XPath. It allows you to retrieve specific nodes from a DOM tree without having to write the code to work your way through the tree. Plus, you can keep the XPath expression as a string in a config file, thus making the code a bit more independent of the XML structure.
We would suggest you to look at an open source API - JDOM. JDOM is an XML parsing API exclusively for Java. It uses DOM API to parse XML files and make the parsed data availabe as Java objects. It can be downloaded from jdom.org. Most the questions are answered in their tutorial, but if you need any help, let us know.