Xpath

------------------------------------------------------------------------------
normalize-space(@name)='value'  去掉空格
not(@name='value') 取非

//*[count(BBB)=2]
//*[count(*)=2]
//*[count(*)=3]

//*[name()='BBB']

//*[starts-with(name(),'B')]

//*[contains(name(),'C')]

//*[string-length(name()) = 3]

//*[string-length(name()) < 3]

//*[string-length(name()) > 3]

---------------------------------------

//CCC | //BBB
/AAA/EEE | //BBB
/AAA/EEE | //DDD/CCC | /AAA | //BBB

--child-------------------------------------

/AAA  等价于  /child::AAA
/AAA/BBB   等价于   /child::AAA/child::BBB
/child::AAA/BBB  可以混合使用

--descendant-------------------------------------

/descendant::*            取得所有子孙节点
/AAA/BBB/descendant::*
//CCC/descendant::*
//CCC/descendant::DDD

--parent-------------------------------------

//DDD/parent::*

--ancestor-------------------------------------

/AAA/BBB/DDD/CCC/EEE/ancestor::*
//FFF/ancestor::*

--following-sibling-------------------------------------

/AAA/BBB/following-sibling::*
//CCC/following-sibling::*

--preceding-sibling-------------------------------------

/AAA/XXX/preceding-sibling::*
//CCC/preceding-sibling::*

--following-------------------------------------

/AAA/XXX/following::*
//ZZZ/following::*

--preceding-------------------------------------

/AAA/XXX/preceding::*
//GGG/preceding::*

--descendant-or-self-------------------------------------

/AAA/XXX/descendant-or-self::*
//CCC/descendant-or-self::*

--ancestor-or-self-------------------------------------

/AAA/XXX/DDD/EEE/ancestor-or-self::*
//GGG/ancestor-or-self::*

---------------------------------------

//GGG/ancestor::*
//GGG/descendant::*
//GGG/following::*
//GGG/preceding::*
//GGG/self::*

--position() -------------------------------------

position() 坐标定位 从  1  开始
floor()  下取整
ceiling()  上取整

//BBB[position() mod 2 = 0 ]
//BBB[ position() = floor(last() div 2 + 0.5) or position() = ceiling(last() div 2 + 0.5) ]
//CCC[ position() = floor(last() div 2 + 0.5) or position() = ceiling(last() div 2 + 0.5) ]