xpath 表达式如何写?
<projects default="x">
<project id="x"></project>
<project id="y"></project>
..........
</projects>
想根据 projects 元素的default属性值,获取project元素
<projects default="x,y">
<project id="x"></project>
<project id="y"></project>
..........
</projects>
想根据 projects 元素的default属性值,获取project元素集