c14n.java

public static byte[] canonicalizeXml(final String aXML) {
		DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = null;
		try {
			InputSource is = new InputSource();
			is.setCharacterStream(new StringReader(aXML));
			
			builderFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false);
			builder = builderFactory.newDocumentBuilder();
			Document xmlDocument = builder.parse(is);
			Node infNFe = xmlDocument.getElementsByTagName("infNFe").item(0);
			
			NamedNodeMap infNFeattributes = infNFe.getAttributes();			
			String versao = infNFeattributes.getNamedItem("versao").getTextContent();
			
			infNFeattributes.removeNamedItem("versao");
			Attr attrVersao = xmlDocument.createAttribute("versao");
			attrVersao.setValue(versao);
			infNFeattributes.setNamedItem(attrVersao);
			
			xmlDocument.getDomConfig().setParameter("canonical-form",true); // EXCEPTION org.w3c.dom.DOMException: FEATURE_NOT_SUPPORTED: O parâmetro canonical-form é reconhecido, mas o valor solicitado não pode ser definido.
			return getXmlString(xmlDocument).getBytes(StandardCharsets.UTF_8);
		} catch (Exception e) {
			throw new EspdNeverStopUtilsException(TspdConstMessages.UTILS_ERRO_TAG, className, e.getMessage());
		}
	}

	private static String getXmlString(Document xmlDocument)
			throws TransformerConfigurationException,
			TransformerFactoryConfigurationError, TransformerException {
		Transformer transformer = TransformerFactory.newInstance().newTransformer();
		transformer.setOutputProperty(OutputKeys.INDENT, "no");
		transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

		//initialize StreamResult with File object to save to file
		StreamResult result = new StreamResult(new StringWriter());
		DOMSource source = new DOMSource(xmlDocument);
		transformer.transform(source, result);

		return result.getWriter().toString();
	}