Best way to read Namespace from XML stream (using Java)

I was wondering if people had some opinions on the following.

I have XML segments like:

<?xml v开发者_JS百科ersion="1.0" encoding="UTF-8"?>
<clashes:MatchingElementAndAttribute xmlns:clashes="http://example.com/AttribElemClashes" clash="123">
        <clash>strval</clash>
</clashes:MatchingElementAndAttribute>

And I want to be able to extract the namespace of the XML fragment.

What is the best way of doing this (within Java) - and the most performant.

Thanks for any help and suggestions

Rob

You can use stax parser like woodstox as it will perform well even with large XMLs. It loads XML as a stream and you will get event for start of the element. It also provides a way to get the QName (Qualified name) of the element as an object which also has the namespace available as a property.

Have a look at http://www.xml.com/pub/a/2003/09/17/stax.html

reading XML that uses Namespaces. Please use the following code exactly, without any even little change.

<?xml version="1.0" encoding="UTF-8" standalone="no"?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:aapi="http://rdf.alchemyapi.com/rdf/v1/s/aapi-schema#" xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#" xmlns:owl="http://www.w3.org/2002/07/owl#" xml:base="http://rdf.alchemyapi.com/rdf/v1/r/response.rdf">
<rdf:Description rdf:ID="d1dfa235105c033dec6dffdff63239d8b802087d9">
    <rdf:type rdf:resource="http://rdf.alchemyapi.com/rdf/v1/s/aapi-schema#DocInfo"/>
    <aapi:ResultStatus>OK</aapi:ResultStatus>
    <aapi:Usage>By accessing AlchemyAPI or using information generated by AlchemyAPI, you are agreeing to be bound by the AlchemyAPI Terms of Use: http://www.alchemyapi.com/company/terms.html</aapi:Usage>
    <aapi:URL/>
    <aapi:Language>english</aapi:Language>
</rdf:Description>
<rdf:Description >

    <aapi:Relevance>0.9683</aapi:Relevance>
    <aapi:Name>Access control</aapi:Name>
        <owl:sameAs rdf:resource="http://dbpedia.org/resource/Access_control"/>
        <owl:sameAs rdf:resource="http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000000051124"/>
</rdf:Description>

for the above XML , you can just use the following good Java code. I suggest you to not search in Google anymore before testing of this code by your own:

import javax.xml.parsers.*;

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);

        DocumentBuilder docBuilder = factory.newDocumentBuilder();

   org.w3c.dom.Document  doc = docBuilder.parse(new InputSource(new StringReader(strAbstractRdf))); 

   NodeList nl = doc.getElementsByTagNameNS("*","Description");    //the tag name

   for (int kk=0;kk< nl.getLength(); kk++)
   {
         Node eDes = nl.item(kk);
         if(eDes.getNodeType() == Node.ELEMENT_NODE)
         {

             Element eDescrition = (Element)eDes;
             NodeList nlTermName= eDescrition.getElementsByTagNameNS("*","Relevance");
             if(nlTermName.getLength() > 0)
             {
                 Element eTermName =(Element) nlTermName.item(0);
                 System.out.println(eTermName.getTextContent());
             }

         }



   }

You shouldn't see a clash here, the fact that your attribute and child element are both called "clash" really shouldn't be a problem.

Do you have an existing parser running at all? Is it having difficulty with this, e.g. throwing exceptions, failing to do what you expect?