Java and XML, Second Edition

JDOM and Factories

Moving right along, recall the discussion from the last chapter on JDOM and factories. I mentioned that you would never see code like this (at least with the current versions) in JDOM applications:

// This code does not work!!
JDOMFactory factory = new JDOMFactory( );
factory.setDocumentClass("javaxml2.BrettsDocumentClass");
factory.setElementClass("javaxml2.BrettsElementClass");

Element rootElement = JDOMFactory.createElement("root");
Document document = JDOMFactory.createDocument(rootElement);

Well, that remains true. However, I glossed over some pretty important aspects of that discussion, and want to pick it up again here. As I mentioned in Chapter 7, being able to have some form of factories allows greater flexibility in how your XML is modeled in Java. Take a look at the simple subclass of JDOM’s Element class shown in Example 8-1.

Example 8-1. Subclassing the JDOM Element class

package javaxml2;

import org.jdom.Element;
import org.jdom.Namespace;

public class ORAElement extends Element {

    private static final Namespace ORA_NAMESPACE =
        Namespace.getNamespace("ora", "http://www.oreilly.com");

    public ORAElement(String name) {
        super(name, ORA_NAMESPACE);
    }

    public ORAElement(String name, Namespace ns) {
        super(name, ORA_NAMESPACE);
    }

    public ORAElement(String name, String uri) {
        super(name, ORA_NAMESPACE);
    }

    public ORAElement(String name, String prefix, String uri) {
        super(name, ORA_NAMESPACE);
    }
}

This is about as simple a subclass as you could come up with; ...