Use of name() function in XPath
In the previous section of XPath in Java
tutorial we have studied about how to use count() function in XPath
query and in our this section we are going to see how we can implement name()
function in the XPath query.
First of all we have created an XML file xmlData.xml.
This xml file contains various nodes and we have used name() function in
our XPathName class to retrieve name of different nodes according to
queries:
Here is the full example code of xmlData.xml as
follows:
xmlData.xml
<?xml version="1.0" ?>
<AAA>
<CCC>
<BBB/>
<BBB/>
<BBB/>
</CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
<EEE>
<BCC/>
<BDD/>
</EEE>
</AAA> |
Now we have declared a class XPathName and
in this class we are parsing the XML file with JAXP. First of all we need
to load the document into DOM Document object. We have put that
xmlData.xml file in that current working directory.
DocumentBuilderFactory domFactory =
DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("xmlData.xml"); |
Above lines of code parses "xmlData.xml"
file and creates a Document object. Next we have created XPath object
with the use of XPathFactory.
XPath xpath = XPathFactory.newInstance().newXPath(); |
Expression "//*[name()='BBB']" will select
all elements with name BBB, equivalent with //BBB, "//*[starts-with(name(),'B')]"
will select all elements name of which starts with letter B and
"//*[contains(name(),'C')]" will select all elements name of which
contain letter C.
Here is the full example code of XPathName.java as follows:
import org.w3c.dom.*;
import javax.xml.xpath.*;
import javax.xml.parsers.*;
import java.io.IOException;
import org.xml.sax.SAXException;
public class XPathName {
public static void main(String[] args)
throws ParserConfigurationException, SAXException,
IOException, XPathExpressionException {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("xmlData.xml");
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile("//*[name()='BBB']");
//Select all elements with name BBB, equivalent with //BBB
System.out.println("Select all elements with name BBB, equivalent with //BBB");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeName());
}
System.out.println("Select all elements name of which starts with letter B");
expr = xpath.compile("//*[starts-with(name(),'B')]");
//Select all elements name of which starts with letter B
result = expr.evaluate(doc, XPathConstants.NODESET);
nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeName());
}
System.out.println("Select all elements name of which contain letter C");
expr = xpath.compile("//*[contains(name(),'C')]");
//Select all elements name of which contain letter C
result = expr.evaluate(doc, XPathConstants.NODESET);
nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeName());
}
}
}
|
Follow these steps to run this example :
- create xmlData.xml
- create and save XPathName.java
- compile and execute XPathName class
Output:
Download Source Code
|
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