How to Evaluate XPath on XML Documents with Default Namespace?

Using XPath on XML Documents with Default Namespace

Problem:

XPath evaluation on XML documents with default namespace proves challenging, particularly without specifying namespace URIs. This issue arises when relying on setNamespaceAware without achieving the desired effect.

Solution:

To utilize XPath effectively with default namespaces, consider the following approaches:

1. NamespaceContext:

Employing a NamespaceContext allows you to manually define namespace mappings, enabling XPath fragments to reference namespaces without prefixing. This approach allows for flexibility in prefix usage and simplifies XPath expressions.

Example Code:

<code class="java">// Custom NamespaceContext
private static class MyNamespaceContext implements NamespaceContext {

    public String getNamespaceURI(String prefix) {
        if ("ns".equals(prefix)) {
            return "http://www.mydomain.com/schema";
        }
        return null;
    }
}

// XPath with NamespaceContext
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setNamespaceContext(new MyNamespaceContext());
NodeList nl = (NodeList) xPath.evaluate("/ns:root/ns:author", dDoc, XPathConstants.NODESET);</code>

2. Avoiding Namespace References:

If using default namespace is unavoidable, adjust XPath expressions to eliminate namespace references altogether. This approach requires adhering to proper XML syntax and ensures consistent behavior across various XML parsing libraries.

Example Code:

<code class="java">XPath xPath = XPathFactory.newInstance().newXPath();
NodeList nl = (NodeList) xPath.evaluate("/root/author", dDoc, XPathConstants.NODESET);</code>

Note:

These techniques allow you to successfully manipulate XML documents with default namespaces using XPath. Remember to customize the namespace declarations within the NamespaceContext or XPath expressions to match your specific XML structure.

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