public static void main(String[] args) throws Exception {

         //获取document

         Document document=getDocument();

         //更新xml

         //UpdateXml(document);

         //添加XML

         //AddXML(document);

         //删除xml

         //DeleXML(document);

         /**

          * 保存

          */

         Save(document);

     }

     /**

      * 1、获得根结点

      * 2、创建结点（设置属性）

      * 3、创建子节点（）

      * 4、添加到根节点

      */

     private static void AddXML(Document document) {

         Element rootElement=document.getDocumentElement();

         Element newElement=document.createElement("book");

         newElement.setAttribute("id", "b003");

         Element PriceElement=document.createElement("title");

         PriceElement.setTextContent("30");

         PriceElement.setAttribute("unit", "￥");

         newElement.appendChild(PriceElement);

         rootElement.appendChild(newElement);

     }

     /**

      * 删除XML

      * 1、获得所有结点

      * 2、获得每一本书

      * 3、获得ID

      * 4、删除

      */

     private static void DeleXML(Document document) {

         NodeList nodeList=document.getElementsByTagName("book");

         for (int i = 0; i < nodeList.getLength(); i++) {

             Node chilNode=nodeList.item(i);

             String id=((Element)chilNode).getAttribute("id");

             if("b001".equals(id))

             {

                 Node parentNode=chilNode.getParentNode();

                 parentNode.removeChild(chilNode);

             }

         }

     }

     /**

      * 更新XML

      * 1、获得所有结点

      * 2、获得每一本书

      * 3、获得ID

      * 4、更新

      *  *1、更新id

      *  *2、更新子节点

      */

     private static void UpdateXml(Document document) {

         NodeList nodeList=document.getElementsByTagName("book");

         for (int i = 0; i < nodeList.getLength(); i++) {

             Node node=nodeList.item(i);

             Element element=(Element) node;

             String id=element.getAttribute("id");

             if("b001".equals(id))

             {

                 //element.setAttribute("id", "booooo"); //更新id值

                 NodeList childNode=element.getElementsByTagName("title");

                     Element childElement=(Element) childNode.item(0);//childNode.getLength()=1

                         childElement.setTextContent("Java核心技术");

             }

         }

     }

     /**

      * 保存xml

      * 1、获得持久化对象实例工厂

      * 2、获得持久化对象

      * 3、将内存数据保存到磁盘

      *   *源————将document对象封装到Source

      *   *结果————将文件路径封装到Result

      * 4、保存

      */

     private static void Save(Document document)

             throws Exception {

         TransformerFactory factory=TransformerFactory.newInstance();

         Transformer transformer=factory.newTransformer();

         Source xmlSource=new DOMSource(document);

         javax.xml.transform.Result outputTarget=new StreamResult("books.jaxp.xml");

         transformer.transform(xmlSource, outputTarget);

         System.out.println("done");

     }

     /**

      * 获取文档

      * 1、获得实例工厂

      * 2、获得解析器

      * 3、获得document

      */

     private static Document getDocument() throws ParserConfigurationException,

             SAXException, IOException {

         DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();

         DocumentBuilder builder=factory.newDocumentBuilder();

         Document document=builder.parse("books.xml");

         return document;

     }