Convertir un XML DOM en String

Document document =...;
    DOMSource domSource = new DOMSource(document);
    StringWriter writer = new StringWriter();
    StreamResult result = new StreamResult(writer);
    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer transformer = tf.newTransformer();
    transformer.transform(domSource, result);
    String stringResult = writer.toString();