JDOM parser can be used to read XML, parse xml and write XML file after updating content of it. It stores JDOM2 document in memory to read and modify it’s values.
After loading XML document into memory, JDOM2 maintains a strict parent-child type relationship. Parent-type JDOM instances (Parent) have methods to access their content, and Child-type JDOM instances (Content) have methods to access their Parent.
Table of Contents Project Structure JDOM2 Maven Dependency Create JDOM2 Document Read and filter XML content Read XML Content with XPath Complete Example Sourcecode Download
Project Structure
Please create this folder structure to execute the examples. It is a simple maven project created in eclipse.
Please note that I have used lambda expressions and method references, so you will need to configure to project to use JDK 1.8.
JDOM2 Maven Dependency
<dependency> <groupId>org.jdom</groupId> <artifactId>jdom2</artifactId> <version>2.0.6</version> </dependency>
To execute XPaths, you will need jaxen as well.
<dependency> <groupId>jaxen</groupId> <artifactId>jaxen</artifactId> <version>1.1.6</version> </dependency>
Create JDOM2 Document
You can create org.jdom2.Document instance using any parser listed down below. They all parse the XML and return in-memory JDOM document.
Using DOM Parser
private static Document getDOMParsedDocument(final String fileName) { Document document = null; try { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); //If want to make namespace aware. //factory.setNamespaceAware(true); DocumentBuilder documentBuilder = factory.newDocumentBuilder(); org.w3c.dom.Document w3cDocument = documentBuilder.parse(fileName); document = new DOMBuilder().build(w3cDocument); } catch (IOException | SAXException | ParserConfigurationException e) { e.printStackTrace(); } return document; }Using SAX Parser
private static Document getSAXParsedDocument(final String fileName) { SAXBuilder builder = new SAXBuilder(); Document document = null; try { document = builder.build(fileName); } catch (JDOMException | IOException e) { e.printStackTrace(); } return document; }Using StAX Parser
private static Document getStAXParsedDocument(final String fileName) { Document document = null; try { XMLInputFactory factory = XMLInputFactory.newFactory(); XMLEventReader reader = factory.createXMLEventReader(new FileReader(fileName)); StAXEventBuilder builder = new StAXEventBuilder(); document = builder.build(reader); } catch (JDOMException | IOException | XMLStreamException e) { e.printStackTrace(); } return document; }
Read and filter XML content
I will be reading employees.xml file.
<employees> <employee id="101"> <firstName>Lokesh</firstName> <lastName>Gupta</lastName> <country>India</country> <department id="25"> <name>ITS</name> </department> </employee> <employee id="102"> <firstName>Brian</firstName> <lastName>Schultz</lastName> <country>USA</country> <department id="26"> <name>DEV</name> </department> </employee> </employees>
Read root node
Use document.getRootElement() method.
public static void main(String[] args)
{
String xmlFile = "employees.xml";
Document document = getSAXParsedDocument(xmlFile);
Element rootNode = document.getRootElement();
System.out.println("Root Element :: " + rootNode.getName());
}
Output:
Root Element :: employees
Read Attribute Value
Use Element.getAttributeValue() method.
public static void main(String[] args)
{
String xmlFile = "employees.xml";
Document document = getSAXParsedDocument(xmlFile);
Element rootNode = document.getRootElement();
rootNode.getChildren("employee").forEach( ReadXMLDemo::readEmployeeNode );
}
private static void readEmployeeNode(Element employeeNode)
{
//Employee Id
System.out.println("Id : " + employeeNode.getAttributeValue("id"));
}
Output:
Id : 101 Id : 102
Read Element Value
Use Element.getChildText() or Element.getText() methods.
public static void main(String[] args)
{
String xmlFile = "employees.xml";
Document document = getSAXParsedDocument(xmlFile);
Element rootNode = document.getRootElement();
rootNode.getChildren("employee").forEach( ReadXMLDemo::readEmployeeNode );
}
private static void readEmployeeNode(Element employeeNode)
{
//Employee Id
System.out.println("Id : " + employeeNode.getAttributeValue("id"));
//First Name
System.out.println("FirstName : " + employeeNode.getChildText("firstName"));
//Last Name
System.out.println("LastName : " + employeeNode.getChildText("lastName"));
//Country
System.out.println("country : " + employeeNode.getChild("country").getText());
/**Read Department Content*/
employeeNode.getChildren("department").forEach( ReadXMLDemo::readDepartmentNode );
}
private static void readDepartmentNode(Element deptNode)
{
//Department Id
System.out.println("Department Id : " + deptNode.getAttributeValue("id"));
//Department Name
System.out.println("Department Name : " + deptNode.getChildText("name"));
}
Output:
FirstName : Lokesh LastName : Gupta country : India Department Id : 25 Department Name : ITS FirstName : Brian LastName : Schultz country : USA Department Id : 26 Department Name : DEV
Read XML Content with XPath
To read any set of element’s value using xpath, You need to compile XPathExpression and use it’s evaluate() method.
String xmlFile = "employees.xml";
Document document = getSAXParsedDocument(xmlFile);
XPathFactory xpfac = XPathFactory.instance();
//Read employee ids
XPathExpression<Attribute> xPathA = xpfac.compile("//employees/employee/@id", Filters.attribute());
for (Attribute att : xPathA.evaluate(document))
{
System.out.println("Employee Ids :: " + att.getValue());
}
//Read employee first names
XPathExpression<Element> xPathN = xpfac.compile("//employees/employee/firstName", Filters.element());
for (Element element : xPathN.evaluate(document))
{
System.out.println("Employee First Name :: " + element.getValue());
}
Output:
Employee Ids :: 101 Employee Ids :: 102 Employee First Name :: Lokesh Employee First Name :: Brian
Complete JDOM2 Read XML Example
Here is complete code to read xml using JDOM2 in java.
package com.howtodoinjava.demo.jdom2;
import java.io.FileReader;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import org.jdom2.Attribute;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.filter.Filters;
import org.jdom2.input.DOMBuilder;
import org.jdom2.input.SAXBuilder;
import org.jdom2.input.StAXEventBuilder;
import org.jdom2.xpath.XPathExpression;
import org.jdom2.xpath.XPathFactory;
import org.xml.sax.SAXException;
@SuppressWarnings("unused")
public class ReadXMLDemo
{
public static void main(String[] args)
{
String xmlFile = "employees.xml";
Document document = getSAXParsedDocument(xmlFile);
/**Read Document Content*/
Element rootNode = document.getRootElement();
System.out.println("Root Element :: " + rootNode.getName());
System.out.println("\n=================================\n");
/**Read Employee Content*/
rootNode.getChildren("employee").forEach( ReadXMLDemo::readEmployeeNode );
System.out.println("\n=================================\n");
readByXPath(document);
}
private static void readEmployeeNode(Element employeeNode)
{
//Employee Id
System.out.println("Id : " + employeeNode.getAttributeValue("id"));
//First Name
System.out.println("FirstName : " + employeeNode.getChildText("firstName"));
//Last Name
System.out.println("LastName : " + employeeNode.getChildText("lastName"));
//Country
System.out.println("country : " + employeeNode.getChild("country").getText());
/**Read Department Content*/
employeeNode.getChildren("department").forEach( ReadXMLDemo::readDepartmentNode );
}
private static void readDepartmentNode(Element deptNode)
{
//Department Id
System.out.println("Department Id : " + deptNode.getAttributeValue("id"));
//Department Name
System.out.println("Department Name : " + deptNode.getChildText("name"));
}
private static void readByXPath(Document document)
{
//Read employee ids
XPathFactory xpfac = XPathFactory.instance();
XPathExpression<Attribute> xPathA = xpfac.compile("//employees/employee/@id", Filters.attribute());
for (Attribute att : xPathA.evaluate(document))
{
System.out.println("Employee Ids :: " + att.getValue());
}
XPathExpression<Element> xPathN = xpfac.compile("//employees/employee/firstName", Filters.element());
for (Element element : xPathN.evaluate(document))
{
System.out.println("Employee First Name :: " + element.getValue());
}
}
private static Document getSAXParsedDocument(final String fileName)
{
SAXBuilder builder = new SAXBuilder();
Document document = null;
try
{
document = builder.build(fileName);
}
catch (JDOMException | IOException e)
{
e.printStackTrace();
}
return document;
}
private static Document getStAXParsedDocument(final String fileName)
{
Document document = null;
try
{
XMLInputFactory factory = XMLInputFactory.newFactory();
XMLEventReader reader = factory.createXMLEventReader(new FileReader(fileName));
StAXEventBuilder builder = new StAXEventBuilder();
document = builder.build(reader);
}
catch (JDOMException | IOException | XMLStreamException e)
{
e.printStackTrace();
}
return document;
}
private static Document getDOMParsedDocument(final String fileName)
{
Document document = null;
try
{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
//If want to make namespace aware.
//factory.setNamespaceAware(true);
DocumentBuilder documentBuilder = factory.newDocumentBuilder();
org.w3c.dom.Document w3cDocument = documentBuilder.parse(fileName);
document = new DOMBuilder().build(w3cDocument);
}
catch (IOException | SAXException | ParserConfigurationException e)
{
e.printStackTrace();
}
return document;
}
/*private static String readFileContent(String filePath)
{
StringBuilder contentBuilder = new StringBuilder();
try (Stream<String> stream = Files.lines( Paths.get(filePath), StandardCharsets.UTF_8))
{
stream.forEach(s -> contentBuilder.append(s).append("\n"));
}
catch (IOException e)
{
e.printStackTrace();
}
return contentBuilder.toString();
}*/
}
Output:
Root Element :: employees ================================= Id : 101 FirstName : Lokesh LastName : Gupta country : India Department Id : 25 Department Name : ITS Id : 102 FirstName : Brian LastName : Schultz country : USA Department Id : 26 Department Name : DEV ================================= Employee Ids :: 101 Employee Ids :: 102 Employee First Name :: Lokesh Employee First Name :: Brian
Sourcecode Download
Happy Learning !!
References: