Xpath & J2ee

Question

Hello,
i have a problem, when i'm trying to parse XML file using XPath expressions i nedd to define a new Class that implements a NameSpaceContext, like this
public class TesteNameSpace implements NamespaceContext {
and then code it like this
public String getNamespaceURI(String prefix) {
     if(prefix.compareToIgnoreCase("rdf") == 0)
          return "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
     else if(prefix.compareToIgnoreCase("prf") == 0)
          return "http://www.openmobilealliance.org/tech/profiles/UAPROF/ccppschema-20021212#";
     else if(prefix.compareToIgnoreCase("mms") == 0)
          return "http://www.wapforum.org/profiles/MMS/ccppschema-20010111#";
     return null;
     }Then i use it like this
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setNamespaceContext(new TesteNameSpace());the problem is that sometime XML files define the same prefix but with a different NameSpace, and my application stops working.
Is there any way a can make a generic code, that i don't need to say what's the namespace ?
Thank you

Answer 1

    private void queryDocument(String fileName, String expr)
        throws XPathFactoryConfigurationException, SAXException {
        try {
            XPathFactory factory = XPathFactory.newInstance();
            XPath xpath = factory.newXPath();
            Document xmlDoc;
            try {
                xmlDoc = getXMLDocument(fileName);
                MyNamespaceContext ctx = new MyNamespaceContext( xmlDoc );
                xpath.setNamespaceContext( ctx );
                NodeList nodes = (NodeList)xpath.evaluate(expr, xmlDoc, XPathConstants.NODESET);
                for(int i = 0; i < nodes.getLength(); i++) {
                    Node n = nodes.item ( i );
                    System.out.println( n.getLocalName() + " = " + n.getTextContent());
            } catch (IOException ex) {
                ex.printStackTrace();
            } catch (ParserConfigurationException ex) {
                ex.printStackTrace();
            } catch (SAXException ex) {
                ex.printStackTrace();
        } catch (XPathExpressionException ex) {
            ex.printStackTrace();
    }The previous code use one context configured to access the Namespaces (prefix and URI in a trasnparent fashion). Here is the NamespaceContext.
final class MyNamespaceContext implements NamespaceContext {
        private HashMap namespaces = new HashMap();
        Document xmlDoc;
        public MyNamespaceContext(Document xmlDoc) {
            this.xmlDoc = xmlDoc;
        public java.util.Iterator getPrefixes(String namespaceURI) {
            return( null );
        public String getPrefix(String namespaceURI) {
            return( xmlDoc.lookupPrefix( namespaceURI )  );
        public String getNamespaceURI(String prefix) {
            return( xmlDoc.lookupNamespaceURI( prefix ));
        public void setNamespace(String prefix, String uri) {
            namespaces.put( prefix, uri );
}Also the small code to load the XML Document requiered in previous queryDocument
private Document getXMLDocument(final String fileName) throws SAXException, ParserConfigurationException, IOException {
DocumentBuilderFactory docBuilderFac = DocumentBuilderFactory.newInstance();
docBuilderFac.setNamespaceAware(true);
DocumentBuilder docBuilder = docBuilderFac.newDocumentBuilder();
Document xmlDoc = docBuilder.parse( new File(fileName) );
return xmlDoc;
I hope that this can help you.
For more information contact me at
Ing. Ilver Anache Pupo
[email protected]
Universidad Peruana de Ciencias Aplicadas (UPC), Per�