Building DOM Trees Through Parsing (SAP Library

Building DOM Trees Through Parsing

Use

The easiest way to get a DOM Tree is to parse an XML file using a DocumentBuilder. Then you can traverse the Document object and extract what you need. The JAXP framework provides several classes to do this but the important ones are:

· javax.xml.pasers.DocumentBuilderFactory

· javax.xml.DocumentBuilder

All you need to do is to invoke DocumentBuilderFactory.newInstance() and then using this instance, to get a new DocumentBuilder – (newDocumentBuilder()). Finally, use the DocumentBuilder instance to parse an XML file, using DocumentBuilder.parse(InputSource). Further, you can specify whether you want your DocumentBuilder to be validating – DocumentBuilderFactory.setValidating(boolean), or to be namespace-aware – DocumentBuilderFactory.setNamespaceAware(boolean).

Example

public class JAXPDOMExample {

public static void main(String args[]) {

try {

String xml= "data/rich_ii.xml";

//get a DocumentBuilderFactory from the underlying

//implementation

DocumentBuilderFactory factory;

ClassLoader oldLoader;

try {

//Although in standalone applications like this one, the classloader

//of the JAXPDOMExample class and the thread context classloader

//are the same, for the sake of completeness preset the loader

oldLoader = Thread.currentThread().getContextClassLoader();

Thread.currentThread().setContextClassLoader(JAXPDOMExample.class.getClassLoader());

factory = DocumentBuilderFactory.newInstance();

} finally {

Thread.currentThread().setContextClassLoader(oldLoader);

}

factory.setValidating(true);

//get a DocumentBuilder from the factory

DocumentBuilder builder = factory.newDocumentBuilder();

//parse the document

Document document = builder.parse(xml);

DOMTraverser domTester = new DOMTraverser();

domTester.traverse1(document);

} catch (Exception e) {

//if there was some error while parsing the file

e.printStackTrace();

}