java 创建xml 字符串

Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();Element cndXml = doc.createElement("CDN_XML");Element askForUpload = doc.createElement("ask_for_upload");Element adi = doc.createElement("ADI");Element metadata = doc.createElement("Metadata");CommonUtil.amsXml(doc, metadata, 1, mapList.get(i));Element appData = doc.createElement("App_Data");appData.setAttribute("App", "VOD");metadata.appendChild(appData);appData.setAttribute("Name", "Metadata_Spec_Version");metadata.appendChild(appData);appData.setAttribute("Value", "CableLabsVOD1.1");metadata.appendChild(appData);adi.appendChild(metadata);askForUpload.appendChild(adi);cndXml.appendChild(askForUpload);Transformer transformer = TransformerFactory.newInstance().newTransformer();transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");transformer.setOutputProperty("version", "1.0");transformer.setOutputProperty(OutputKeys.INDENT, "yes");DOMSource source = new DOMSource(apis);StringWriter strReturn = new StringWriter();transformer.transform(source, new StreamResult(strReturn));retString = strReturn.toString();