用jdom向一个element添加element出错!!org.jdom.IllegalAddException:

[sparkcn]

对于如下的xml
<?xml version="1.0" encoding="GBK"?>
<bookList>
<book>
<name>Java编程入门</name>
<author>张三</author>
<publishDate>2002-6-6</publishDate>
<price>35.0</price>
</book>
</bookList>

我想再添加一个
<book>
<name>Java编程入门</name>
<author>张三</author>
<publishDate>2002-6-6</publishDate>
<price>35.0</price>
</book>
可是却抱错误:
错误!org.jdom.IllegalAddException: The elemen
t "book" could not be added as the root of the document: The Content already has
an existing parent document

我的代码是:
===========================得到要被添加的element==========================
org.jdom.input.SAXBuilder sb=new org.jdom.input.SAXBuilder();
//创建文档
org.jdom.Document doc=sb.build(new FileInputStream("c:\\example.xml"));
//获得这个文档得跟元素
org.jdom.Element el=doc.getRootElement();
//获得这个跟元素，的所有子元素
========================================================================
org.jdom.Element elTempObject=el.getChild("book");


el.addContent(elTempObject);//这句话就抱错!!!!


请问各位大哥怎么解决?

[xdop]

btw:

The exception text is 'org.jdom.IllegalAddException: The element "book" could not be added as the root of the document: The Content already has an existing parent document'

Therefore,u cannot assign a couple of parents to an element.

[xdop]

我认为应该给新节点重新分配空间,clone另一个book对象,然后再 add
而不是直接把现有节点的引用 elTempObject 直接 add

xml被jdom引擎在内存中解析,产生了一系列的"对象树",java机区别对象的途径是hash码.
如果获取一个对象的引用:
org.jdom.Element elTempObject=el.getChild("book");
然后又再次添加到dom结构:
el.addContent(elTempObject); // elTempObject引用的对象已经存在,hash码是冲突的
对象树无法确认这个操作