如何遍历xml
xml文件如下,不知怎么遍历出所有值,求教
<?xml version="1.0" encoding="gb2312"?>
<userinfo>
<clas uid="1" uno="101" uname="a" utype="1">
<guid gname="wx" gtype="3" />
<home addr="" mobil="" mail=""/>
<friendm>
<friendm fnum="" fname="" />
</friendm>
<friendwm fnum="" fname=""/>
</clas>
<clas uid="2" uno="102" uname="b" utype="1">
<guid gname="we" gtype="3" />
<home addr="" mobil="" mail=""/>
<friendm>
<friendm fnum="" fname="" />
</friendm>
<friendwm fnum="" fname=""/>
</clas>
<clas uid="3" uno="1011" uname="c" utype="1">
<guid gname="zf" gtype="3" />
<home addr="" mobil="" mail=""/>
<friendm>
<friendm fnum="" fname="" />
</friendm>
<friendwm fnum="" fname=""/>
</clas>
</userinfo>