Java操作XML工具类XmlUtil详解

public class XmlUtil {
 /**
 * 将XML文件输出到指定的路径
 * 
 * @param doc
 * @param fileName
 * @throws Exception
 */
 public static void outputXml(Document doc, String fileName)
 throws Exception {
 TransformerFactory tf = TransformerFactory.newInstance();
 Transformer transformer = tf.newTransformer();
 DOMSource source = new DOMSource(doc);
 transformer.setOutputProperty(OutputKeys.ENCODING, \"UTF-8\");
 transformer.setOutputProperty(OutputKeys.INDENT, \"yes\");
 PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
 StreamResult result = new StreamResult(pw);
 transformer.transform(source, result);
 System.out.println(\"生成XML文件成功!\");
 }
 
 /**
 * 生成XML
 * 
 * @param ip
 * @return
 */
 public static Document generateXml(String ip) {
 Document doc = null;
 Element root = null;
 try {
 DocumentBuilderFactory factory = DocumentBuilderFactory
  .newInstance();
 DocumentBuilder builder = factory.newDocumentBuilder();
 doc = builder.newDocument();
 root = doc.createElement(\"errorDevices\");
 doc.appendChild(root);
 } catch (Exception e) {
 e.printStackTrace();
 return null;// 如果出现异常，则不再往下执行
 }
 
 Element element;
 element = doc.createElement(\"errorDevice\");
 element.setAttribute(\"ip\", ip);
 element.setAttribute(\"date\",
 StringUtil.formatDate(new Date(), \"yyyy-MM-dd hh:mm:ss\"));
 element.setAttribute(\"status\", \"1\");
 root.appendChild(element);
 return doc;
 }
 
 /**
 * 新增Xml节点
 * 
 * @param ip
 * @param fileName
 * @return
 * @throws FileNotFoundException
 * @throws TransformerException
 */
 public static void toWrite(String filename, String ip)
 throws FileNotFoundException, TransformerException {
 String date = StringUtil.formatDate(new Date(), \"yyyy-MM-dd hh:mm:ss\");
 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 DocumentBuilder builder = null;
 Document doc = null;
 try {
 builder = factory.newDocumentBuilder();
 doc = builder.parse(new File(filename));
 } catch (ParserConfigurationException e) {
 e.printStackTrace();
 } catch (SAXException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 NodeList links = doc.getElementsByTagName(\"errorDevice\");
 if (links.getLength() > 0) {
 for (int i = 0; i < links.getLength(); i++) {
 Node nd = links.item(i);
 Node catParent = nd.getParentNode();
 Element ele = (Element) nd;
 String url = ele.getAttribute(\"ip\");
 if (url.equals(ip)) {
  // ele.setAttribute(\"date\", date);
  catParent.removeChild(nd);
 }
 }
 }
 Element element = doc.createElement(\"errorDevice\");
 element.setAttribute(\"ip\", ip);
 element.setAttribute(\"date\",
 StringUtil.formatDate(new Date(), \"yyyy-MM-dd hh:mm:ss\"));
 element.setAttribute(\"status\", \"1\");
 doc.getDocumentElement().appendChild(element);
 TransformerFactory tf = TransformerFactory.newInstance();
 Transformer transformer = tf.newTransformer();
 DOMSource source = new DOMSource(doc);
 transformer.setOutputProperty(OutputKeys.ENCODING, \"UTF-8\");
 transformer.setOutputProperty(OutputKeys.INDENT, \"yes\");
 PrintWriter pw = new PrintWriter(new FileOutputStream(filename));
 StreamResult result = new StreamResult(pw);
 transformer.transform(source, result);
 System.out.println(\"新增XML节点成功!\");
 }
 
 /**
 * 读取XML
 * 
 * @param filename
 * @return
 */
 public static List<Map> readXml(String filename){
 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 DocumentBuilder builder = null;
 Document doc = null;
 try {
 builder = factory.newDocumentBuilder();
 doc = builder.parse(new File(filename));
 } catch (ParserConfigurationException e) {
 e.printStackTrace();
 } catch (SAXException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 NodeList links = doc.getElementsByTagName(\"errorDevice\");
 List<Map> list = new ArrayList<Map>();
 for(int i = 0; i< links.getLength() ; i ++){
   Element node = (Element)links.item(i);
   Map map = new HashMap();
   map.put(node.getAttribute(\"ip\"), node.getAttribute(\"date\"));
   list.add(map);
 }
 return list;
 }
}

<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>
<errorDevices>
 <errorDevice date=\"2017-03-13 12:54:16\" ip=\"20.100.156.42\" status=\"1\"/>
 <errorDevice date=\"2017-03-13 12:54:56\" ip=\"20.100.156.41\" status=\"1\"/>
</errorDevices>