JDOM XPath Getting Inner Element without Namespace

Question

I have an xml like this:

<root
    xmlns:gl-bus="http://www.xbrl.org/int/gl/bus/2006-10-25"
    xmlns:gl-cor="http://www.xbrl.org/int/gl/cor/2006-10-25" >
    <gl-cor:entityInformation>
        <gl-bus:accountantInformation>
            ...............
        </gl-bus:accountantInformation>
    </gl-cor:entityInformation>
</root>

All I want to extract the element "gl-cor:entityInformation" from the root with its child elements. However, I do not want the namespace declarations come with it.

The code is like this:

XPathExpression<Element> xpath = XPathFactory.instance().compile("gl-cor:entityInformation", Filters.element(), null, NAMESPACES);
Element innerElement = xpath.evaluateFirst(xmlDoc.getRootElement());

The problem is that the inner element holds the namespace declarations now. Sample output:

<gl-cor:entityInformation xmlns:gl-cor="http://www.xbrl.org/int/gl/cor/2006-10-25">
    <gl-bus:accountantInformation xmlns:gl-bus="http://www.xbrl.org/int/gl/bus/2006-10-25">
    </gl-bus:accountantInformation>
</gl-cor:entityInformation>

This is how I get xml as string:

public static String toString(Element element) {
    Format format = Format.getPrettyFormat();
    format.setTextMode(Format.TextMode.NORMALIZE);
    format.setEncoding("UTF-8");

    XMLOutputter xmlOut = new XMLOutputter(); 
    xmlOut.setFormat(format);
    return xmlOut.outputString(element);
}

As you see the namespace declarations are passed into the inner elements. Is there a way to get rid of these declarations without losing the prefixes?

I want this because later on I will be merging these inner elements inside another parent element and this parent element has already those namespace declarations.

Answer 1

JDOM by design insists that the in-memory model of the XML is well structured at all times. The behaviour you are seeing is exactly what I would expect from JDOM and I consider it to be "right". JDOM's XMLOutputter also outputs well structured and internally consistent XML and XML fragments.

Changing the bahaviour of the internal in-memory model is not an option with JDOM, but customizing the XMLOutputter to change its behaviour is relatively easy. The XMLOutputter is structured to have an "engine" supplied as a constructor argument: XMLOutputter(XMLOutputProcessor). In addition, JDOM supplies an easy-to-customize default XMLOutputProcessor called AbstractXMLOutputProcessor.

You can get the behaviour you want by doing the following:

private static final XMLOutputProcessor noNamespaces = new AbstractXMLOutputProcessor() {

    @Override
    protected void printNamespace(final Writer out, final FormatStack fstack, 
        final Namespace ns)  throws IOException {
        // do nothing with printing Namespaces....
    }

};

Now, when you create your XMLOutputter to print your XML element fragment, you can do the following:

public static String toString(Element element) {
    Format format = Format.getPrettyFormat();
    format.setTextMode(Format.TextMode.NORMALIZE);
    format.setEncoding("UTF-8");

    XMLOutputter xmlOut = new XMLOutputter(noNamespaces); 
    xmlOut.setFormat(format);
    return xmlOut.outputString(element);
}

Here's a full program working with your input XML:

import java.io.IOException;
import java.io.Writer;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.Namespace;
import org.jdom2.filter.Filters;
import org.jdom2.input.SAXBuilder;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;
import org.jdom2.output.support.AbstractXMLOutputProcessor;
import org.jdom2.output.support.FormatStack;
import org.jdom2.output.support.XMLOutputProcessor;
import org.jdom2.xpath.XPathExpression;
import org.jdom2.xpath.XPathFactory;


public class JDOMEray {

    public static void main(String[] args) throws JDOMException, IOException {
        Document eray = new SAXBuilder().build("eray.xml");
        Namespace[] NAMESPACES = {Namespace.getNamespace("gl-cor", "http://www.xbrl.org/int/gl/cor/2006-10-25")};
        XPathExpression<Element> xpath = XPathFactory.instance().compile("gl-cor:entityInformation", Filters.element(), null, NAMESPACES);
        Element innerElement = xpath.evaluateFirst(eray.getRootElement());

        System.out.println(toString(innerElement));
    }

    private static final XMLOutputProcessor noNamespaces = new AbstractXMLOutputProcessor() {

        @Override
        protected void printNamespace(final Writer out, final FormatStack fstack, 
            final Namespace ns)  throws IOException {
            // do nothing with printing Namespaces....
        }

    };

    public static String toString(Element element) {
        Format format = Format.getPrettyFormat();
        format.setTextMode(Format.TextMode.NORMALIZE);
        format.setEncoding("UTF-8");

        XMLOutputter xmlOut = new XMLOutputter(noNamespaces); 
        xmlOut.setFormat(format);
        return xmlOut.outputString(element);
    }


}

For me the above program outputs:

<gl-cor:entityInformation>
  <gl-bus:accountantInformation>...............</gl-bus:accountantInformation>
</gl-cor:entityInformation>