How to query XML using namespaces in Java with XPath?

user_160120 0
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When my XML looks like this (no xmlns) then I can easly query it with XPath like /workbook/sheets/sheet[1]

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<workbook>
  <sheets>
    <sheet name="Sheet1" sheetId="1" r:id="rId1"/>
  </sheets>
</workbook>

But when it looks like this then I can't

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
  <sheets>
    <sheet name="Sheet1" sheetId="1" r:id="rId1"/>
  </sheets>
</workbook>

Any ideas?

xml-namespaces xpath xml java
8 Answers

If you are using Spring, it already contains org.springframework.util.xml.SimpleNamespaceContext. 

        import org.springframework.util.xml.SimpleNamespaceContext;
        ...

        XPathFactory xPathfactory = XPathFactory.newInstance();
        XPath xpath = xPathfactory.newXPath();
        SimpleNamespaceContext nsc = new SimpleNamespaceContext();

        nsc.bindNamespaceUri("a", "http://some.namespace.com/nsContext");
        xpath.setNamespaceContext(nsc);

        XPathExpression xpathExpr = xpath.compile("//a:first/a:second");

        String result = (String) xpathExpr.evaluate(object, XPathConstants.STRING);
user_23315290

Startlingly, if I don't set factory.setNamespaceAware(true); then the xpath you mentioned does work with and without namespaces at play. You just aren't able to select things "with namespace specified" only generic xpaths. Go figure. So this may be an option:

 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 factory.setNamespaceAware(false);
user_324530

Two things to add to the existing answers:

  • I don't know whether this was the case when you asked the question: With Java 10, your XPath actually works for the second document if you don't use setNamespaceAware(true) on the document builder factory (falseis the default).

  • If you do want to use setNamespaceAware(true), other answers have already shown how to do this using a namespace context. However, you don't need to provide the mapping of prefixes to namespaces yourself, as these answers do: It's already there in the document element, and you can use that for your namespace context:

import java.util.Iterator;

import javax.xml.namespace.NamespaceContext;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class DocumentNamespaceContext implements NamespaceContext {
    Element documentElement;

    public DocumentNamespaceContext (Document document) {
        documentElement = document.getDocumentElement();
    }

    public String getNamespaceURI(String prefix) {
        return documentElement.getAttribute(prefix.isEmpty() ? "xmlns" : "xmlns:" + prefix);
    }

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

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

The rest of the code is as in the other answers. Then the XPath /:workbook/:sheets/:sheet[1] yields the sheet element. (You could also use a non-empty prefix for the default namespace, as the other answers do, by replacing prefix.isEmpty() by e.g. prefix.equals("spreadsheet") and using the XPath /spreadsheet:workbook/spreadsheet:sheets/spreadsheet:sheet[1].)

P.S.: I just found here that there's actually a method Node.lookupNamespaceURI(String prefix), so you could use that instead of the attribute lookup:

    public String getNamespaceURI(String prefix) {
        return documentElement.lookupNamespaceURI(prefix.isEmpty() ? null : prefix);
    }

Also, note that namespaces can be declared on elements other than the document element, and those wouldn't be recognized (by either version).

user_6030820
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