XPath /A/B/C/@a works, but /A/A/A/@a doesn't ...

Question

I get XPath values for simple XML files without problems (element values or attribute values). Now I have an XML file where a quite simple XPath doesn't work:
<?xml version="1.0" encoding="UTF-8" ?>
<gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref">
     <gesmes:subject>Reference rates</gesmes:subject>
     <gesmes:Sender>
          <gesmes:name>European Central Bank</gesmes:name>
     </gesmes:Sender>
     <Cube>
          <Cube time="2005-06-15">
               <Cube currency="USD" rate="1.2069" />
          </Cube>
     </Cube>
</gesmes:Envelope>The XPaths "/gesmes:Envelope/Cube/Cube/@time" or "//Cube/Cube/@time" don't work. I notice that the element names of different hierarchies are the same so I built a similar XML with distinguished element names and there my xpath works. Alas, the XML file is the source that I can't change. So is there another way to state an XPath to get the time value?

Answer 1

I use this code:
     * Get value of the node specified by an XPath.
     * @param item The starting context (e.g. document, node, node list).
     * @param xPath XPath to select single node value (e.g. "/root/data/value[1]/text()")
     * @return Result of <i>xPath</i> (the node's value) or null if failed.
     * @throws XPathExpressionException if <i>xPath</i> is wrong.
    static public String getXPathValue(Object item, String xPath) throws XPathExpressionException {
        String result = null;
        if (item != null && xPath != null) {
            try {
                result = XPathFactory.newInstance().newXPath().evaluate(xPath, item);
            } catch (NullPointerException npe) {
                //XPathFactory.newInstance() throws NullPointerException when called from ActiveX bean
                if (item instanceof Document) {
                    result = getXPathValueApache((Document) item, xPath);
//            if (ICUtils.isEmptyString(result)) {
//                XPath xp = XPathFactory.newInstance().newXPath();
//                xp.setNamespaceContext(new javax.xml.namespace.NamespaceContext () {
//                    public String getNamespaceURI (String prefix) {
//                        if (prefix.equals("rsp")) {
//                          return "http://schemas.xmlsoap.org/soap/envelope/";
//                        else if (prefix.equals(javax.xml.XMLConstants.XML_NS_PREFIX)) {
//                          return javax.xml.XMLConstants.XML_NS_URI;
//                        else if (prefix.equals(javax.xml.XMLConstants.XMLNS_ATTRIBUTE)) {
//                          return javax.xml.XMLConstants.XMLNS_ATTRIBUTE_NS_URI;
//                        else {
//                          return javax.xml.XMLConstants.NULL_NS_URI;
//                    public String getPrefix (String namespaceURI) {
//                        if (namespaceURI.equals(javax.xml.XMLConstants. "http://schemas.xmlsoap.org/soap/envelope/")) {
//                            return "rsp";
//                          else if (namespaceURI.equals(javax.xml.XMLConstants.XML_NS_URI)) {
//                            return javax.xml.XMLConstants.XML_NS_PREFIX;
//                          else if (namespaceURI.equals(javax.xml.XMLConstants.XMLNS_ATTRIBUTE_NS_URI)) {
//                            return javax.xml.XMLConstants.XMLNS_ATTRIBUTE;
//                          else {
//                            return null;
//                    public Iterator getPrefixes (String namespaceURI) {
//                        // not implemented for the example
//                        return null;
//                result = xp.evaluate(xPath, item);
            //workaround for non working XPaths of SOAP messages:
            if (ICUtils.isEmptyString(result) && item instanceof Document) {
                //some XPaths for SOAP Messages don't work with Java API:
                String r  = getXPathValueApache((Document) item, xPath);
                if (!ICUtils.isEmptyString(r)) {
                    result = r;
        }//else: input values not available
        return result;
    }//getXPathValue()
     * Get value of the node specified by an XPath.
     * @param document Document to get node value of.
     * @param xPath XPath to select single node value (e.g. "/root/data/value[1]/text()")
     * @return Result of <i>xPath</i> (the node's value) or null if failed.
     * @throws org.w3c.dom.xpath.XPathException if XPath result object is not of type XPathResult.
     * @see <a href="http://www.w3schools.com/xpath/default.asp">XPath Tutorial</a>
    static private String getXPathValueApache(Document document, String xPath) throws org.w3c.dom.xpath.XPathException {
        String result = null;
        if (document != null && xPath != null) {        
            org.w3c.dom.xpath.XPathEvaluator evaluator = new org.apache.xpath.domapi.XPathEvaluatorImpl(document);
            Object o = evaluator.evaluate(xPath, document, evaluator.createNSResolver(document), org.w3c.dom.xpath.XPathResult.FIRST_ORDERED_NODE_TYPE, null);
            if (o != null) {
                if (o instanceof org.w3c.dom.xpath.XPathResult) {
                    org.w3c.dom.xpath.XPathResult xpResult = (org.w3c.dom.xpath.XPathResult) o;
                    Node node = xpResult.getSingleNodeValue();
                    if (node != null) {
                        result = node.getNodeValue();   
                } else {
                    throw new org.w3c.dom.xpath.XPathException(org.w3c.dom.xpath.XPathException.TYPE_ERR, "XPath '"+xPath+"' didn't return an object of type  XPathResult!");
            }//else: no result for XPath
        }//else: input values not available
        return result;
    }//getXPathValue()and it works well with "normal" XML files (distinguished element names) and also to get element attribute values. But for this specific XML (posted above), the XPaths don't work.