Thứ Ba, 28 tháng 5, 2013

How To Modify XML File In Java – (DOM Parser)

In this example, we demonstrate the use of DOM parser to modify an existing XML file :


  1. Add a new element

  2. Update existing element attribute

  3. Update existing element value

  4. Delete existing element


1. XML file


See before and after XML file.

File : file.xml – Original XML file.


 
VD.
<!--?xml version="1.0" encoding="UTF-8" standalone="no" ?>

yong
mook kim
mkyong
100000

Later, update above XML file via DOM XML Parser.




  1. Update the staff attribute id = 2

  2. Update salary value to 200000

  3. Append a new “age” element under staff

  4. Delete “firstname” element under staff


File : file.xml – Newly modified XML file.

VD.


mook kim
mkyong
2000000
28


2. DOM Parser


DOM XML parser to update an above XML file.


import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class ModifyXMLFile {

public static void main(String argv[]) {

try {
String filepath = "c:\\file.xml";
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.parse(filepath);

// Get the root element
Node company = doc.getFirstChild();

// Get the staff element , it may not working if tag has spaces, or
// whatever weird characters in front...it's better to use
// getElementsByTagName() to get it directly.
// Node staff = company.getFirstChild();

// Get the staff element by tag name directly
Node staff = doc.getElementsByTagName("staff").item(0);

// update staff attribute
NamedNodeMap attr = staff.getAttributes();
Node nodeAttr = attr.getNamedItem("id");
nodeAttr.setTextContent("2");

// append a new node to staff
Element age = doc.createElement("age");
age.appendChild(doc.createTextNode("28"));
staff.appendChild(age);

// loop the staff child node
NodeList list = staff.getChildNodes();

for (int i = 0; i < list.getLength(); i++) {

Node node = list.item(i);

// get the salary element, and update the value
if ("salary".equals(node.getNodeName())) {
node.setTextContent("2000000");
}

//remove firstname
if ("firstname".equals(node.getNodeName())) {
staff.removeChild(node);
}

}

// write the content into xml file
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File(filepath));
transformer.transform(source, result);

System.out.println("Done");

} catch (ParserConfigurationException pce) {
pce.printStackTrace();
} catch (TransformerException tfe) {
tfe.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (SAXException sae) {
sae.printStackTrace();
}
}
}


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