public class MappedNamespaceContext implements NamespaceContext {

	private Map<String, String> uriMap = new HashMap<String, String>();

	public void addUri(String prefix, String uri) {		uriMap.put(prefix, uri);	}

	public String getNamespaceURI(String prefix) {		if (prefix == null) throw new NullPointerException("Null prefix");                else if (uriMap.containsKey(prefix)) return uriMap.get(prefix);                else if ("xml".equals(prefix)) return XMLConstants.XML_NS_URI;                return XMLConstants.NULL_NS_URI;	}

	public String getPrefix(String namespaceURI) {		throw new UnsupportedOperationException();	}

	public Iterator getPrefixes(String namespaceURI) {		throw new UnsupportedOperationException();	}

}

// parse the docDocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();domFactory.setNamespaceAware(true); DocumentBuilder builder = domFactory.newDocumentBuilder();Document doc = builder.parse(is);

// setup the namespaces for Yahoo! Weather RSSMappedNamespaceContext ctx = new MappedNamespaceContext();ctx.addUri("yweather", "http://xml.weather.yahoo.com/ns/rss/1.0");ctx.addUri("geo","http://www.w3.org/2003/01/geo/wgs84_pos#");

// get the resultXPathFactory factory = XPathFactory.newInstance();XPath xpath = factory.newXPath();xpath.setNamespaceContext(ctx);XPathExpression expr = xpath.compile(xpathExpression);NodeList result = (NodeList)expr.evaluate(doc, XPathConstants.NODESET);