dom4j操作xml对象

     // 获取Documen对象

     public static Document getDocument(String path) throws Exception{

            // 解析器对象

           SAXReader reader = new SAXReader();

            // 解析

            return reader.read(path);

     }

     // 回写（XMLWriter）

     public static void writeXml(Document document,String path) throws Exception{

            // 格式

           OutputFormat format = OutputFormat.createPrettyPrint();

            // 设置编码

           format.setEncoding( "UTF-8");

            XMLWriter writer = new XMLWriter (new FileOutputStream(path), format);

            // 进行回写

           writer.write(document);

            // 关闭流

           writer.close();

     }

// 使用工具类，操作XML

           Document document = MyXmlUtil.getDocument(MyXmlUtil. PATH);

            // 解析XML

            // 获取根节点（查文档）

           Element root = document.getRootElement();

            // 校验用户名或者邮箱是否重名

           List<Element> uList = root.elements("user");

            // 判断

            if(uList != null || uList.size() > 0){

                 // XML中查询，和传入过来做对比，如果相同，重名了，返回

                 // 从XML中获取的

                 for (Element u : uList) {

                      // 获取username 节点的文本内容

                      // u.element("username ").getText();

                     String xmlName = u.elementText("username");

                      // 获取传入进来的User 的名称

                     String uName = user.getUsername();

                      // 重名了，返回1

                      if(xmlName.equals(uName)){

                            return MyXmlUtil.NAMEEXIST;

                     }

                      // 获取xmlEamil

                     String xmlEmail = u.elementText( "email");

                     String uEamil = user.getEmail();

                      if(xmlEmail.equals(uEamil)){

                            return MyXmlUtil.EMAILEXIST;

                     }

                }

           }

            // 需要在XML添加节点

           Element uElement = root.addElement( "user");

            // 添加子节点

          uElement.addElement( "username").setText(user.getUsername());

          uElement.addElement( "password").setText(user.getPassword());

          uElement.addElement( "nickname").setText(user.getNickname());

          uElement.addElement( "email").setText(user.getEmail());

            // 回写

            MyXmlUtil.writeXml(document, MyXmlUtil .PATH );

            // 返回1 用户名重名了，返回是2邮箱重名，返回0注册成功

            return MyXmlUtil.SUCCESS;