XPath语法(7)

2015-07-18 05:46:00
admin
原创 450
摘要:XPath的相关知识

 

//GGG/self::*

 


     <AAA> 
          <BBB> 
               <CCC/> 
               <ZZZ/> 
          </BBB> 
          <XXX> 
               <DDD> 
                    <EEE/> 
                    <FFF> 
                         <HHH/> 
                         <GGG> 
                              <JJJ> 
                                   <QQQ/> 
                              </JJJ> 
                              <JJJ/> 
                         </GGG> 
                         <HHH/> 
                    </FFF> 
               </DDD> 
          </XXX> 
          <CCC> 
               <DDD/> 
          </CCC> 
     </AAA> 

  

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

 


     <AAA> 
          <BBB> 
               <CCC/> 
               <ZZZ/> 
          </BBB> 
          <XXX> 
               <DDD> 
                    <EEE/> 
                    <FFF> 
                         <HHH/> 
                         <GGG> 
                              <JJJ> 
                                   <QQQ/> 
                              </JJJ> 
                              <JJJ/> 
                         </GGG> 
                         <HHH/> 
                    </FFF> 
               </DDD> 
          </XXX> 
          <CCC> 
               <DDD/> 
          </CCC> 
     </AAA> 

 

div运算符做浮点除法运算, mod运算符做求余运算, floor函数返回不大于参数的最大整数(趋近于正无穷), ceiling返回不小于参数的最小整数(趋近于负无穷)

  

//BBB[position() mod 2 = 0 ]

选择偶数位置的BBB元素


     <AAA> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <CCC/> 
          <CCC/> 
          <CCC/> 
     </AAA> 

  

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

选择中间的BBB元素


     <AAA> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <CCC/> 
          <CCC/> 
          <CCC/> 
     </AAA> 

  

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

选择中间的CCC元素


     <AAA> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <BBB/> 
          <CCC/> 
          <CCC/> 
          <CCC/> 
     </AAA> 

 

 

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