XPath is used to parse a XML document whenever we know what we have to parse like: tag name, attribute name. That means we can directly indicate and parse whatever(tag or attribute value) we want to parse.
Lets see an example:
package com.sourav.xpathex;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
/**
*
* @author Kayum-603
*/
/**
we are going to parse the below XML file:
*
*
<company>
<customers>
<customer cusId="1" deskNo="1">
<firstname>Euna</firstname>
<lastname>Islam</lastname>
<username>E Islam</username>
<position>Software Engineer</position>
</customer>
<customer cusId="2" deskNo="2">
<firstname>Mamun</firstname>
<lastname>Kayum</lastname>
<username>Mamun_Kayum</username>
<position>Software Engineer</position>
</customer>
<customer cusId="3" deskNo="3">
<firstname>Gulam</firstname>
<lastname>Samdani</lastname>
<username>Masum</username>
<position>Software Engineer</position>
</customer>
</customers>
</company>
*/
public class XPathEX {
public void readFile() {
// reading the file
ClassLoader classLoader = getClass().getClassLoader();
File fileDir = new File(classLoader.getResource("resources/customer.xml").getFile());
String nodeValue;
String attributeValue;
String firstName;
if (fileDir.exists()) { // if the xml is exist
System.out.println("file found");
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse(new FileInputStream(fileDir));// same xml comments as above.
XPathFactory xpf = XPathFactory.newInstance();
XPath xpath = xpf.newXPath();
String nodeLavel = "/company/customers/customer";
// reading attribute value
Element userElement = (Element) xpath.evaluate(nodeLavel, document,
XPathConstants.NODE);
attributeValue = userElement.getAttribute("deskNo"); // will return first child node's 'deskNo' attribute value
System.out.println("Value of attribute 'Desk No:' " + attributeValue);
attributeValue = userElement.getAttribute("cusId");
System.out.println("Value of attribute 'Customer no:' " + attributeValue);
nodeValue = userElement.getElementsByTagName("firstname").item(0).getTextContent();
System.out.println("value of clild node 'firstname:' " + nodeValue);
// read all child node 'firstname' values
NodeList nodeList = (NodeList) xpath.compile(nodeLavel).evaluate(document, XPathConstants.NODESET);
for (int i = 0; i < nodeList.getLength(); i++) {
Node nNode = nodeList.item(i);
Element userElementForNodes = (Element) nNode;
nodeValue = userElementForNodes.getElementsByTagName("firstname").item(0).getTextContent();
System.out.println("value of clild node 'firstname:' " + nodeValue);
}
} catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException e) {
}
} else {
System.out.println("file not found");
}
}
public static void main(String[] args) {
XPathEX readObj = new XPathEX();
readObj.readFile();
}
}
Where our XML file is:
<?xml version="1.0" encoding="UTF-8"?> <company> <customers> <customer cusId="1" deskNo="1"> <firstname>Euna</firstname> <lastname>Islam</lastname> <username>E Islam</username> <position>Software Engineer</position> </customer> <customer cusId="2" deskNo="2"> <firstname>Mamun</firstname> <lastname>Kayum</lastname> <username>Mamun_Kayum</username> <position>Software Engineer</position> </customer> <customer cusId="3" deskNo="3"> <firstname>Gulam</firstname> <lastname>Samdani</lastname> <username>Masum</username> <position>Software Engineer</position> </customer> </customers> </company>
