XML XPath: Đọc XML bằng XPath (Có điều kiện)

Question_8

Main.java

Java XML 2016

package xpath_p1;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
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.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class Main {

    public static void main(String[] args) {

        try {
            FileInputStream file = new FileInputStream(
                    new File("src\\xpath_p1\\input.xml"));
            DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = builderFactory.newDocumentBuilder();
            Document xmlDocument = builder.parse(file);

            XPath xPath = XPathFactory.newInstance().newXPath();
            
            System.out.println("*************************");
            String expression = "/Employees/Employee/firstname";
            NodeList nodeList = (NodeList) xPath.compile(expression)
                    .evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }
            
            
            System.out.println("*************************");
            expression = "/Employees/Employee[@emplid='3333']/email";
            System.out.println(expression);
            String email = xPath.compile(expression).evaluate(xmlDocument);
            System.out.println(email);

            
            System.out.println("*************************");
            expression = "/Employees/Employee[@type='admin']/firstname";
            System.out.println(expression);
            nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            System.out.println("*************************");
            expression = "/Employees/Employee[@emplid='2222']";
            System.out.println(expression);
            Node node = (Node) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODE);
            if (null != node) {
                nodeList = node.getChildNodes();
                for (int i = 0; null != nodeList && i < nodeList.getLength(); i++) {
                    Node nod = nodeList.item(i);
                    if (nod.getNodeType() == Node.ELEMENT_NODE) {
                        System.out.println(nodeList.item(i).getNodeName() + " : " + nod.getFirstChild().getNodeValue());
                    }
                }
            }

            System.out.println("*************************");

            expression = "/Employees/Employee[age>35]/firstname";
            nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
            System.out.println(expression);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            System.out.println("*************************");
            expression = "/Employees/Employee[1]/firstname";
            System.out.println(expression);
            nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }
            System.out.println("*************************");
            expression = "/Employees/Employee[position() <= 2]/firstname";
            System.out.println(expression);
            nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            System.out.println("*************************");
            expression = "/Employees/Employee[last()]/firstname";
            System.out.println(expression);
            nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            System.out.println("*************************");

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (XPathExpressionException e) {
            e.printStackTrace();
        }
    }
}

input.xml

Java XML 2016

<?xml version="1.0"?>
<Employees>
    <Employee emplid="1111" type="admin">
        <firstname>John</firstname>
        <lastname>Watson</lastname>
        <age>30</age>
        <email>johnwatson@sh.com</email>
    </Employee>
    <Employee emplid="2222" type="admin">
        <firstname>Sherlock</firstname>
        <lastname>Homes</lastname>
        <age>32</age>
        <email>sherlock@sh.com</email>
    </Employee>
    <Employee emplid="3333" type="user">
        <firstname>Jim</firstname>
        <lastname>Moriarty</lastname>
        <age>52</age>
        <email>jim@sh.com</email>
    </Employee>
    <Employee emplid="4444" type="user">
        <firstname>Mycroft</firstname>
        <lastname>Holmes</lastname>
        <age>41</age>
        <email>mycroft@sh.com</email>
    </Employee>
</Employees>

Output