如何在Java中使用XPath解析此xml？

Question

<?xml version="1.0" encoding="utf-8"?> <double xmlns="http://www.somewebsite.com/">2.0</double>

I'm having a bit of trouble parsing this using XPath 1.0.

this is what i do:

XPath xpath = XPath.newInstance("/double"); Element returnElement = (Element) xpath.selectSingleNode(doc);

the return element is null but it should be 2.0.

NOTE: It should be using XPath 1.0

Answer 1

The double element is in the http://www.somewebsite.com/ namespace. Map the namespace to a prefix (eg foo ) and resolve with a qualified expression (eg /foo:double ).

Using the standard API:

String xml = "<double xmlns='http://www.somewebsite.com/'>2.0</double>";
Reader reader = new StringReader(xml);
XPath xpath = XPathFactory.newInstance()
                          .newXPath();
NamespaceContext context = new NamespaceContextMap("foo", "http://www.somewebsite.com/");
xpath.setNamespaceContext(context);
String value = xpath.evaluate("/foo:double", new InputSource(reader));
System.out.println(value);

You can find a sample implementation of NamespaceContext on my blog .