1、你的XML文件缩进就有问题,改成这样:
<company>
<folder checkbox="true" title="lizong"  code="1" expanded="false" >
<leaf checkbox="true" title="mazong" code="2"/>
<folder checkbox="true" title="jishubu"  code="3"  >
<leaf checkbox="true" title="chen" code="4"/>
<leaf checkbox="true" title="wang" code="5"/>
<leaf checkbox="true" title="liu" code="6"/>
<leaf checkbox="true" title="yan" code="7"/>
<leaf checkbox="true" title="zhang" code="8"/>
</folder>
<leaf checkbox="true" title="sizong" code="9"/>
<folder checkbox="true" title="shichangbu"  code="10" >
<leaf checkbox="true" title="wang" code="11"/>
<leaf checkbox="true" title="yu" code="12"/>
</folder>
<leaf checkbox="true" title="fengzong" code="13"/>
<folder checkbox="true" title="xingzhengbu"  code="14" >
<leaf checkbox="true" title="wang" code="15"/>
</folder>
</folder>
</company>
2、如果是为了搞个树形结构体,那最好别分folder和leaf,统统用leaf
3、问问题前先看搜索:http://community.csdn.net/Expert/FAQ/FAQ_Index.asp?id=93890
4、XML相关的问题到XML版去问是最佳选择