Clean namespace handling with dom4j

Option 1 is dangerous because you can't guarantee the prefixes for a given namespace without pre-parsing the document, and because you can end up with namespace collision. If you're consuming a document and not outputting anything, it might be ok, depending on the source of the doc, but otherwise it just loses too much information.

Option 2 could be applied recursively but its got many of the same problems as option 1.

Option 3 sounds like the best approach, but rather than clutter your code, make a static method that does both checks rather than putting the same if statement throughout your codebase.

The best approach is to get whoever is sending you the bad XML to fix it. Of course this begs the question is it actually broken. Specifically, are you getting XML where the default namespace is defined as X and then a namespace also representing X is given a prefix of 'es'? If this is the case then the XML is well formed and you just need code that is agnostic about the prefix, but still uses a qualified name to fetch the element. I'm not familiar enough with Dom4j to know if creating a Namespace with a null prefix will cause it to match all elements with a matching URI or only those with no prefix, but its worth experimenting with.

As Abhishek, I needed to strip the namespace from XML to simplify XPath queries in system testing scripts. (the XML is first XSD validated)

Here are the problems I faced:

1. I needed to process deeply structured XML that had a tendency of blowing up the stack.
2. On most complex XML, for a reason I didn't investigate fully, stripping all the namespaces only worked in reliably when traversing the DOM tree depth first. So that excluded the visitor, or getting the list of nodes with document.selectNodes("//*")

I ended up with the following (not the most elegant, but if that can help solving somebody's problem ...):

public static String normaliseXml(final String message) {
    org.dom4j.Document document;
    document = DocumentHelper.parseText(message);

    Queue stack = new LinkedList();

    Object current = document.getRootElement();

    while (current != null) {
        if (current instanceof Element) {
            Element element = (Element) current;

            Iterator iterator = element.elementIterator();

            if (iterator.hasNext()) {
                stack.offer(element);
                current = iterator;
            } else {
                stripNamespace(element);

                current = stack.poll();
            }
        } else {
            Iterator iterator = (Iterator) current;

            if (iterator.hasNext()) {
                stack.offer(iterator);
                current = iterator.next();
            } else {
                current = stack.poll();

                if (current instanceof Element) {
                    stripNamespace((Element) current);

                    current = stack.poll();
                }
            }
        }
    }

    return document.asXML();
}

private static void stripNamespace(Element element) {
    QName name = new QName(element.getName(), Namespace.NO_NAMESPACE, element.getName());
    element.setQName(name);

    for (Obj