Short summary of XML processing - parse, manipulate, output

xmlprocessing.java

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class ... {

	public static void main(String argv[]) throws Exception {
		File fXmlFile = new File(...);
		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
		DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
		Document doc = dBuilder.parse(fXmlFile);

		// optional, but recommended
		// read this -
		// http://stackoverflow.com/questions/13786607/normalization-in-dom-parsing-with-java-how-does-it-work
		doc.getDocumentElement().normalize();
		
		XPathFactory xPathfactory = XPathFactory.newInstance();
		XPath xpath = xPathfactory.newXPath();
		XPathExpression expr = xpath.compile("/plugin/extension[@point='org.nasdanika.cdo.web.renderer']/renderer");
		NodeList result = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
		System.out.println(result);

		for (int i = 0; i < result.getLength(); ++i) {
			Element eObjectRoute = (Element) result.item(i);
			eObjectRoute.setAttribute("renderer", "some attribute");
		}
		
		XPathExpression textExtExpr = xpath.compile("/plugin/extension[@point='org.nasdanika.cdo.web.test']");
		Element testExt = (Element) textExtExpr.evaluate(doc, XPathConstants.NODE);
		if (testExt == null) {
			testExt = doc.createElement("extension");
			testExt.setAttribute("point", "org.nasdanika.cdo.web.test");
			((Element) xpath.compile("/plugin").evaluate(doc, XPathConstants.NODE)).appendChild(testExt);
		}
		
		//doc.importNode(node, true);
		
	    // Use a Transformer for output
	    TransformerFactory tFactory = TransformerFactory.newInstance();
	    Transformer transformer = tFactory.newTransformer();
	    transformer.setOutputProperty(OutputKeys.INDENT, "yes");
	    
	    DOMSource source = new DOMSource(doc);
	    StreamResult out = new StreamResult(System.out);
	    transformer.transform(source, out);
		
	}

}