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XPath最通俗的教程

http://www.diybl.com/ 2008-10-17  网络 点击:  [ 评论 ]
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  以下是本人找到的最完整最易懂的XPath教程,不敢私藏,拿出来与大家分享。

实例 1
基本的XPath语法类似于在一个文件系统中定位文件,如果路径以斜线 / 开始, 那么该路径就表示到一个元素的绝对路径

/AAA

选择根元素AAA


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

 

/AAA/CCC

选择AAA的所有CCC子元素


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

 

/AAA/DDD/BBB

选择AAA的子元素DDD的所有子元素


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

 

 

实例 2

如果路径以双斜线 // 开头, 则表示选择文档中所有满足双斜线//之后规则的元素(无论层级关系)

 

//BBB

选择所有BBB元素


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

 

//DDD/BBB

选择所有父元素是DDDBBB元素


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

 

 

实例 3

星号 * 表示选择所有由星号之前的路径所定位的元素

 

/AAA/CCC/DDD/*

选择所有路径依附于/AAA/CCC/DDD的元素


     <AAA>
          <XXX>
               <DDD>
                    <BBB/>
                    <BBB/>
                    <EEE/>
                    <FFF/>
               </DDD>
          </XXX>
          <CCC>
               <DDD>
                    <
BBB/>
                    <
BBB/>
                    <
EEE/>
                    <
FFF/>
               </DDD>
          </CCC>
          <CCC>
               <BBB>
                    <BBB>
                         <BBB/>
                    </BBB>
               </BBB>
          </CCC>
     </AAA>

 

/*/*/*/BBB

选择所有的有3个祖先元素的BBB元素


     <AAA>
          <XXX>
               <DDD>
                    <
BBB/>
                    <
BBB/>
                    <EEE/>
                    <FFF/>
               </DDD>
          </XXX>
          <CCC>
               <DDD>
                    <
BBB/>
                    <
BBB/>
                    <EEE/>
                    <FFF/>
               </DDD>
          </CCC>
          <CCC>
               <BBB>
                    <
BBB>
                         <BBB/>
                    </
BBB>
               </BBB>
          </CCC>
     </AAA>

 

//*

选择所有元素


     <
AAA>
          <
XXX>
               <
DDD>
                    <
BBB/>
                    <
BBB/>
                    <
EEE/>
                    <
FFF/>
               </
DDD>
          </
XXX>
          <
CCC>
               <
DDD>
                    <
BBB/>
                    <
BBB/>
                    <
EEE/>
                    <
FFF/>
               </
DDD>
          </
CCC>
          <
CCC>
               <
BBB>
                    <
BBB>
                         <
BBB/>
                    </
BBB>
               </
BBB>
          </
CCC>
     </
AAA>

 

 

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