源demo.xml
<?xml version="1.0" encoding="UTF-8"?>
<root>
<users>
<user name="111" time="2009-05-05">
<questions>
<question>
<questionId>1</questionId>
<answer>A</answer>
</question>
<question>
<questionId>2</questionId>
<answer>b</answer>
</question>
</questions>
</user>
<user name="222" time="2009-05-05">
<questions>
<question>
<questionId>3</questionId>
<answer>c</answer>
</question>
<question>
<questionId>4</questionId>
<answer>d</answer>
</question>
</questions>
</user>
</users>
</root>
现在又一个String addxml="<user name="123" time="2009-05-29 15:58:34"><question><questionId>1</question><answer>C</answer></question><question><questionId>2</question><answer>C</answer></question></user>
"我想用dom4j的技术吧这些添加到users下面，应该怎么做