dom4j解析
增删改查

src/book.xml

<书架> 
  <书> 
    <书名 id="a1" name="shuming">JAVA1</书名>  
    <作者>张1</作者>  
    <价格>109</价格> 
  </书>  
  <书> 
    <书名 name="XXXX">JAVA2</书名>  
    <作者>hhh</作者>  
    <价格>12(2)</价格> 
  </书> 
</书架>

public class demo5 {
    //读取XML文档第二本书的 <书名>JAVA2</书名>
    @Test
    public  void read()throws Exception
    {
          SAXReader reader = new SAXReader();
          Document document = reader.read(new File("src/book.xml"));

          Element root = document.getRootElement();
          Element element =  (Element) root.elements("书").get(1);
          String valueString =  element.element("书名").getText();
          System.out.println(valueString);
    }
    //得到第二本书的属性 <书名 name="XXXX">JAVA2</书名>
    @Test
    public  void readAttr()throws Exception
    {
          SAXReader reader = new SAXReader();
          Document document = reader.read(new File("src/book.xml"));

          Element root = document.getRootElement();

          Element book =  (Element) root.elements("书").get(1);
          String valueString =  book.element("书名").attributeValue("name");
          System.out.println(valueString);
    }
    //在第一本书上添加一个新的售价<售价>209元</售价>
    @Test
    public void add() throws Exception
    {
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));

        Element book = document.getRootElement().element("书");
        book.addElement("售价").setText("209元");

        OutputFormat of = OutputFormat.createPrettyPrint();
        of.setEncoding("UTF-8");

        XMLWriter writer = new XMLWriter( new FileOutputStream("src/book.xml"),of);
        writer.write( document );
        writer.close();
    }
    //在第一本书指定位置添加新的售价<售价>209元</售价> 更改list集合顺序
    @Test
    public void add2()throws Exception
    {
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));
        Element book = document.getRootElement().element("书");
        List<Element> list = book.elements();

        Element price =DocumentHelper.createElement("售价");
        price.setText("209元");

        list.add(2,price);

        OutputFormat of = OutputFormat.createPrettyPrint();
        of.setEncoding("UTF-8");

        XMLWriter writer = new XMLWriter( new FileOutputStream("src/book.xml"),of);
        writer.write( document );
        writer.close();
    }
    //删除第一本书的 <售价>209元</售价>
    @Test
    public  void delete()throws Exception
    {
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));
        Element price = document.getRootElement().element("书").element("售价");
        price.getParent().remove(price);

        OutputFormat of = OutputFormat.createPrettyPrint();
        of.setEncoding("UTF-8");

        XMLWriter writer = new XMLWriter( new FileOutputStream("src/book.xml"),of);
        writer.write( document );
        writer.close();
    }
    //更新第二本书的作者
    @Test
    public void update() throws Exception
    {
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));

        Element book = (Element) document.getRootElement().elements("书").get(1);
        book.element("作者").setText("hhh");
        OutputFormat of = OutputFormat.createPrettyPrint();
        of.setEncoding("UTF-8");

        XMLWriter writer = new XMLWriter( new FileOutputStream("src/book.xml"),of);
        writer.write( document );
        writer.close();
    }
}