Set namespace using jdom

问题

I would like have this format in xml:

<ns2: test xmlns="url" xmlns:ns2="url2" xmlns:ns3="url3">
....
</ns2: test>

I am using the following code:

    Namespace ns= Namespace.getNamespace("url");
    Namespace ns2 = Namespace.getNamespace("ns2", "url2");
    Namespace ns3= Namespace.getNamespace("ns3", "url3");

    SAXBuilder vDocBuilder = new SAXBuilder();
    Document vDocument = vDocBuilder.build(File);

    System.out.println("Root element " + vDocument.getRootElement().getName());

    org.jdom.Element test = new org.jdom.Element("test", ns);
    vDocument.setRootElement(test);
    vNewRootElement.addNamespaceDeclaration(ns2);
    vNewRootElement.addNamespaceDeclaration(ns3);

If I set namespace with:

    vNewRootElement.setNamespace(ns3);

Then I get thi:s

    <ns2: test xmlns:ns2="url2" xmlns:ns3="url3"> ... </ns2: test> 
without the default namespace xmlns="url".

Can anybody tell me why it dosen't work and is there a way to solve this problem?

Thanks, haner

回答1:

The following outputs (to System.out)

<?xml version="1.0" encoding="UTF-8"?>
<ns2:test xmlns:ns2="url2" xmlns="url" xmlns:ns3="url3">Some text</ns2:test>

---

import java.io.IOException;
import org.jdom.Document;
import org.jdom.JDOMException;
import org.jdom.Namespace;
import org.jdom.output.XMLOutputter;

public class Test {

    public static void main(String args[]) throws JDOMException, IOException {
        Namespace ns = Namespace.getNamespace("url");
        Namespace ns2 = Namespace.getNamespace("ns2", "url2");
        Namespace ns3 = Namespace.getNamespace("ns3", "url3");


        Document vDocument = new Document();
        org.jdom.Element test = new org.jdom.Element("test", ns2);
        vDocument.setRootElement(test);
        //add "url" default namespace
        test.addNamespaceDeclaration(ns);
        test.addNamespaceDeclaration(ns2);
        test.addNamespaceDeclaration(ns3);
        test.addContent("Some text");
        //dump output to System.out
        XMLOutputter xo = new XMLOutputter();
        xo.output(vDocument, System.out);

    }
}

you need the line

   test.addNamespaceDeclaration(ns);

来源：https://stackoverflow.com/questions/7085503/set-namespace-using-jdom