Java HTML / XML How to - Use XPath with namespace

Question

We would like to know how to use XPath with namespace.
Answer

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/*from   ww w.  j a  v  a  2 s  . co  m*/
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Main {
  public static void main(String[] args) throws Exception {
    DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
    domFactory.setValidating(false);
    domFactory.setNamespaceAware(true);
    domFactory.setIgnoringComments(true);
    domFactory.setIgnoringElementContentWhitespace(true);

    DocumentBuilder builder = domFactory.newDocumentBuilder();
    Document dDoc = builder.parse("C:/data.xsd");

    Node rootNode = dDoc.getElementsByTagName("xs:schema").item(0);
    System.out.println(rootNode.getNodeName());

    XPath xPath1 = XPathFactory.newInstance().newXPath();
    NamespaceContext nsContext = new NamespaceContext() {
      @Override
      public String getNamespaceURI(String prefix) {
        return "http://www.w3.org/2001/XMLSchema";
      }

      @Override
      public String getPrefix(String namespaceURI) {
        return "xs";
      }

      @Override
      public Iterator getPrefixes(String namespaceURI) {
        Set s = new HashSet();
        s.add("xs");
        return s.iterator();
      }
    };
    xPath1.setNamespaceContext((NamespaceContext) nsContext);
    NodeList nList1 = (NodeList) xPath1.evaluate("//xs:schema", dDoc,
        XPathConstants.NODESET);
    System.out.println(nList1.item(0).getNodeName());

     NodeList nList2 = (NodeList) xPath1.evaluate("//xs:element", rootNode,
        XPathConstants.NODESET);
    System.out.println(nList2.item(0).getNodeName());
  }
}