DOM, NODE -- MyNode??

Question

Hi,
I need to do some implementation for a research project on XML. Basically I need to parse an XML document using DOM.
Then traverse the tree structure with the help of NODE. I will take advantage of the comprehensive functions provided by interface NODE, e.g. getAttributes(), getFirstChildNode()...However, i still
need to accommodate some additional information, such as the path for each node,e.g. Root.Child1.grandChild2.... To associate such extra data, I plan to create a subclass of NODE, MyNode, which may also implement
some methods, such as setPath(), getPath()...for extra usage of 'path' information.
My questions are:
1. Since NODE is of type Interface, is it possible to create such a subclass, MyNode of it??
If yes, how should this be done? Since the tree structure is built by built-in function of DOM. Seems like no human intervention is allowed during the tree-building process.A typical piece of code using DOM may be:
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder =  factory.newDocumentBuilder();
Document document = builder.parse("hello.xml");
Element root = document.getDocumentElement();
Node textNode = root.getFirstChild();
System.out.println(textNode.getNodeValue());
Blah Blah...How should the above snippet be adapted to fit MyNode? I think probably I should change the 4th line to:
MyNode root = builder.parse("hello.xml");
Will this work as intended?
2. How should the subclass, MyNode be constructed??
What is in my mind is as follows:
public class MyNode extends Element
//or here maybe Node, this goes back to my first question;I am not exactly sure which should be the parent class)  =|
   {       String path = "";
     //the constructor
     public MyNode(Node originalNode){
          super();     //should I invoke the constructor of its parent, NODE here???
          this.setPath();
     void setPath(){
           this.path = (MyNode)(this.getParentNode()).getPath() + (MyNode)(this.getParentNode()).getNodeName();
     String getPath(){
           return this.path;
    }Will the above construction of class MyNode work properly??
Many thanks in advance for any help on this topic. Some code example is very appreciated.
Frank

Answer 1

Many thanks for your reply.
I looked into your point.I understand that later versions of DOM support association of extra user information to any NODE object, by pairwisely using setUserData(String key, Object data, UserDataHandler handler), getUserData(String key), as illustrated at http://java.sun.com/j2se/1.5.0/docs/guide/plugin/dom/org/w3c/dom/Node.html. So besides all parsing automation of DOM in my implementation, I still have to explicitly specify the extra information, by setUserData for each NODE object before actually calling the getUserData method.More precisely, I should give it a NAME, presented by key, and the value for each object, object, while both key and object refer back to the command syntax above. Is my understanding correct?
I dont know the version of the code example in my 1st post of setting up a DOM parser. Can I directly invoke the two commands directly? The other aspect is that the project is based on my work last year, in which the DOM parser was set up running that way. In case it is not a DOM3, i.e. the 2 useful functions are not available to its version, can I simply upgrade it to DOM3 standard by ONLY modify its setup to something* like:
System.setProperty(DOMImplementationRegistry.PROPERTY,
      "org.apache.xerces.dom.DOMImplementationSourceImpl");
    DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
     DOMImplementation impl = registry.getDOMImplementation("[XML_file_name]");  //The parameter was originally 'LS-Load', is this the XML file name??
    if (impl == null) {
        System.err.println("Coudl not locate a DOM3 Parser");
        return;   
    DOMImplementationLS implls = (DOMImplementationLS) impl;
    LSParser parser = implls.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);
    Document d = parser.parseURI(args); //Where can I specify the XML document to be parsed?? I wont need to use 'NameSpace' by the way.
*:an excerpt from Section 'Parsing documents with DOM3' on http://www.ibiblio.org/xml/slides/sd2004west/dom3/DOM_Level_3.html
Will this 'upgrading' successful? If so, most part of work last year may be reused without further modification.
To be frank, I dont really understand how this excerpt works. Can you plese explain a bit more? If it is not the proper setting up of the DOM parser incorporating the two useful functions, can you please refer me to the right direction?
Thanks & Have an awesome weekend
Frank