Java and XML, Second Edition

Chapter 5. DOM

In the previous chapters, I’ve talked about Java and XML in the general sense, but I have described only SAX in depth. As you may be aware, SAX is just one of several APIs that allow XML work to be done within Java. This chapter and the next will widen your API knowledge as I introduce the Document Object Model, commonly called the DOM. This API is quite a bit different from SAX, and complements the Simple API for XML in many ways. You’ll need both, as well as the other APIs and tools in the rest of this book, to be a competent XML developer.

Because DOM is fundamentally different from SAX, I’ll spend a good bit of time discussing the concepts behind DOM, and why it might be used instead of SAX for certain applications. Selecting any XML API involves tradeoffs, and choosing between DOM and SAX is certainly no exception. I’ll move on to possibly the most important topic: code. I’ll introduce you to a utility class that serializes DOM trees, something that the DOM API itself doesn’t currently supply. This will provide a pretty good look at the DOM structure and related classes, and get you ready for some more advanced DOM work. Finally, I’ll show you some problem areas and important aspects of DOM in the “Gotcha!” section.

The Document Object Model

The Document Object Model, unlike SAX, has its origins in the World Wide Web Consortium (W3C). Whereas SAX is public-domain software, developed through long discussions on the XML-dev mailing list, DOM is a standard just ...