Как создать xml в Java?

DocumentBuilderFactory documentBuilderFactory = 
     DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = 
     documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.newDocument();    
Element rootElement = document.createElement("rootelmt");
document.appendChild(rootElement);
Element eCmd = document.createElement("seclevelelmt");
eCmd.appendChild(document.createTextNode(cmd));
rootElement.appendChild(eCmd);    
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(document);
java.io.StringWriter os = new java.io.StringWriter();
javax.xml.transform.stream.StreamResult result = new javax.xml.transform.stream.StreamResult(os);
transformer.transform(source,result);        
System.out.println(os.toString());