Below is a Java Xml DOM Tutorial program to demonstrate how to work with XML using Java API
This program will illustrate the following concepts;
- The Creation of an XML Document, element node, attribute node, comment node, processing instruction and a CDATA section
- How to use DOM to work with XML
- How to build a DOM Tree
- How to write a DOM tree to a file
- How to read a DOM tree from a file
- How to read the Nodes of a DOM tree
This example below creates a file “Employee.xml” in the same path as that of the source code path
[sourcecode language='java']
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Attr;
import org.w3c.dom.Comment;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
class Employees {
private String gender;
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public Employees(String name, String gender, String name2) {
firstName = name;
this.gender = gender;
lastName = name2;
}
public String toString() {
return firstName + “\t” + gender + “\t” + lastName;
}
}
public class BuildXmlUsingDom {
private Document document;
public BuildXmlUsingDom() {
DocumentBuilderFactory dBF = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = dBF.newDocumentBuilder(); // java xml documentbuilder
document = builder.newDocument();
} catch (ParserConfigurationException parserException) {
parserException.printStackTrace();
}
Element root = document.createElement(”Employees”);
document.appendChild(root);
// add comment to XML document
Comment simpleComment = document.createComment(”Employee Details”);
root.appendChild(simpleComment);
// add Employee child elements
Node employeeNode = createEmployees(document);
root.appendChild(employeeNode);
// We can also add processing instructions and java xml cdata Sections as shown
/*
* ProcessingInstruction pi = document.createProcessingInstruction(
* “myInstruction”, “action silent”); root.appendChild(pi);
*
* CDATASection cdata = document .createCDATASection(”I can add <, >,
* and ?”); root.appendChild(cdata);
*/
// write the XML document to disk
try {
// create DOMSource for source XML document
Source xmlSource = new DOMSource(document);
// create StreamResult for transformation result
Result result = new StreamResult(new FileOutputStream(
“Employee.xml”));
// create TransformerFactory
TransformerFactory transformerFactory = TransformerFactory
.newInstance();
// create Transformer for transformation
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(”indent”, “yes”); //Java XML Indent
// transform and deliver content to client
transformer.transform(xmlSource, result);
}
// handle exception creating TransformerFactory
catch (TransformerFactoryConfigurationError factoryError) {
System.err.println(”Error creating ” + “TransformerFactory”);
factoryError.printStackTrace();
} catch (TransformerException transformerError) {
System.err.println(”Error transforming document”);
transformerError.printStackTrace();
} catch (IOException ioException) {
ioException.printStackTrace();
}
}
public Node createEmployees(Document document) {
// create FirstName and LastName elements
Element firstName = document.createElement(”FirstName”);
Element lastName = document.createElement(”LastName”);
// java xml text
firstName.appendChild(document.createTextNode(”Shawn”));
lastName.appendChild(document.createTextNode(”Michaels”));
// create employee element
Element employee = document.createElement(”Employee”);
// java xml attributes
Attr genderAttribute = document.createAttribute(”gender”);
genderAttribute.setValue(”M”);
// append attribute to contact element
employee.setAttributeNode(genderAttribute);
employee.appendChild(firstName);
employee.appendChild(lastName);
return employee;
}
// Function to read DOM Tree from File
public Document readingXMLFromFile() {
DocumentBuilderFactory dBF = DocumentBuilderFactory.newInstance();
dBF.setIgnoringComments(true); // Ignore the comments present in the
// XML File when reading the xml
DocumentBuilder builder = null;
try {
builder = dBF.newDocumentBuilder();
} catch (ParserConfigurationException e) {
e.printStackTrace();
}
InputSource input = new InputSource(”Employee.xml”);
Document doc = null;
try {
doc = builder.parse(input);
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return doc;
}
/*
* Employee.xml
*
*
*
*
*/
public ArrayList CreateListOfObjects(Document doc) {
ArrayList
Element root = doc.getDocumentElement();
// Retrieve the list of Empolyee Nodes
NodeList employeeList = root.getElementsByTagName(”Employee”);
for (int i = 0; i < employeeList.getLength(); i++) {
Element employeeElement = (Element) employeeList.item(i);
String gender = employeeElement.getAttribute("gender");
// java xml nodelist
NodeList firstNameList = employeeElement
.getElementsByTagName("FirstName");
Element firstNameElement = (Element) firstNameList.item(0);
Text firstNameText = (Text) firstNameElement.getFirstChild();
String fName = firstNameText.getNodeValue();
NodeList lastNameList = employeeElement
.getElementsByTagName("LastName");
Element lastNameElement = (Element) lastNameList.item(0);
Text lastNameText = (Text) lastNameElement.getFirstChild();
String lName = lastNameText.getNodeValue();
Employees emp = new Employees(fName, gender, lName);
employeesList.add(emp);
}
return employeesList;
}
public static void main(String args[]) {
BuildXmlUsingDom buildXmlUsingDom = new BuildXmlUsingDom();
System.out
.println("Processing Employee.xml to create Employee Objects");
Document doc = buildXmlUsingDom.readingXMLFromFile();
ArrayList
.CreateListOfObjects(doc);
System.out.println(”The Employee Objects are”);
for (int i = 0; i < empList.size(); i++) {
System.out.println(empList.get(i));
}
}
}
[/sourcecode]
Leave a Reply