XPath手册

[[注:]本手册由ZVON版本加工而成,对JQuery感兴趣的朋友可以看一下源代码]

页首

• /AAA
• /AAA/CCC
• /AAA/DDD/BBB
• //BBB
• //DDD/BBB
• /AAA/CCC/DDD/*
• /*/*/*/BBB
• //*
• /AAA/BBB[1]
• /AAA/BBB[last()]
• //@id
• //BBB[@id]
• //BBB[@name]
• //BBB[@*]
• //BBB[not(@*)]
• //BBB[@id='b1']
• //BBB[@name='bbb']
• //BBB[normalize-space(@name)='bbb']
• //*[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
• /AAA
• /child::AAA
• /AAA/BBB
• /child::AAA/child::BBB
• /child::AAA/BBB
• /descendant::*
• /AAA/BBB/descendant::*
• //CCC/descendant::*
• //CCC/descendant::DDD
• //DDD/parent::*
• /AAA/BBB/DDD/CCC/EEE/ancestor::*
• //FFF/ancestor::*
• /AAA/BBB/following-sibling::*
• //CCC/following-sibling::*
• /AAA/XXX/preceding-sibling::*
• //CCC/preceding-sibling::*
• /AAA/XXX/following::*
• //ZZZ/following::*
• /AAA/XXX/preceding::*
• //GGG/preceding::*
• /AAA/XXX/descendant-or-self::*
• //CCC/descendant-or-self::*
• /AAA/XXX/DDD/EEE/ancestor-or-self::*
• //GGG/ancestor-or-self::*
• //GGG/ancestor::*
• //GGG/descendant::*
• //GGG/following::*
• //GGG/preceding::*
• //GGG/self::*
• //GGG/ancestor::* | //GGG/descendant::* | //GGG/following::* | //GGG/preceding::* | //GGG/self::*
• //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) ]

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> 回页首 /AAA/CCC选择AAA的所有CCC子元素
     <AAA>
          <BBB/>
          <CCC/>
          <BBB/>
          <BBB/>
          <DDD>
               <BBB/>
          </DDD>
          <CCC/>
     </AAA> 回页首 /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> 回页首

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> 回页首 //DDD/BBB选择所有父元素是DDD的BBB元素
     <AAA>
          <BBB/>
          <CCC/>
          <BBB/>
          <DDD>
               <BBB/>
          </DDD>
          <CCC>
               <DDD>
                    <BBB/>
                    <BBB/>
               </DDD>
          </CCC>
     </AAA> 回页首

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> 回页首 /*/*/*/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> 回页首 //*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> 回页首

方块号里的表达式可以进一步的指定元素, 其中数字表示元素在选择集里的位置, 而last()函数则表示选择集中的最后一个元素.

/AAA/BBB[1]选择AAA的第一个BBB子元素
     <AAA>
          <BBB/>
          <BBB/>
          <BBB/>
          <BBB/>
     </AAA> 回页首 /AAA/BBB[last()]选择AAA的最后一个BBB子元素
     <AAA>
          <BBB/>
          <BBB/>
          <BBB/>
          <BBB/>
     </AAA> 回页首 //@id选择所有的id属性
     <AAA>
          <BBB id = "b1"/>
          <BBB id = "b2"/>
          <BBB name = "bbb"/>
          <BBB/>
     </AAA> 回页首 //BBB[@id]选择有id属性的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB id = "b2"/>
          <BBB name = "bbb"/>
          <BBB/>
     </AAA> 回页首 //BBB[@name]选择有name属性的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB id = "b2"/>
          <BBB name = "bbb"/>
          <BBB/>
     </AAA> 回页首 //BBB[@*]选择有任意属性的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB id = "b2"/>
          <BBB name = "bbb"/>
          <BBB/>
     </AAA> 回页首 //BBB[not(@*)]选择没有属性的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB id = "b2"/>
          <BBB name = "bbb"/>
          <BBB/>
     </AAA> 回页首

属性的值可以被用来作为选择的准则, normalize-space函数删除了前部和尾部的空格, 并且把连续的空格串替换为一个单一的空格

//BBB[@id='b1']选择含有属性id且其值为'b1'的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB name = " bbb "/>
          <BBB name = "bbb"/>
     </AAA> 回页首 //BBB[@name='bbb']选择含有属性name且其值为'bbb'的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB name = " bbb "/>
          <BBB name = "bbb"/>
     </AAA> 回页首 //BBB[normalize-space(@name)='bbb']选择含有属性name且其值(在用normalize-space函数去掉前后空格后)为'bbb'的BBB元素
     <AAA>
          <BBB id = "b1"/>
          <BBB name = " bbb "/>
          <BBB name = "bbb"/>
     </AAA> 回页首

count()函数可以计数所选元素的个数

//*[count(BBB)=2]选择含有2个BBB子元素的元素
     <AAA>
          <CCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </CCC>
          <DDD>
               <BBB/>
               <BBB/>
          </DDD>
          <EEE>
               <CCC/>
               <DDD/>
          </EEE>
     </AAA> 回页首 //*[count(*)=2]选择含有2个子元素的元素
     <AAA>
          <CCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </CCC>
          <DDD>
               <BBB/>
               <BBB/>
          </DDD>
          <EEE>
               <CCC/>
               <DDD/>
          </EEE>
     </AAA> 回页首 //*[count(*)=3]选择含有3个子元素的元素
     <AAA>
          <CCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </CCC>
          <DDD>
               <BBB/>
               <BBB/>
          </DDD>
          <EEE>
               <CCC/>
               <DDD/>
          </EEE>
     </AAA> 回页首

name()函数返回元素的名称, start-with()函数在该函数的第一个参数字符串是以第二个参数字符开始的情况返回true, contains()函数当其第一个字符串参数包含有第二个字符串参数时返回true.

//*[name()='BBB']选择所有名称为BBB的元素(这里等价于//BBB)
     <AAA>
          <BCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </BCC>
          <DDB>
               <BBB/>
               <BBB/>
          </DDB>
          <BEC>
               <CCC/>
               <DBD/>
          </BEC>
     </AAA> 回页首 //*[starts-with(name(),'B')]选择所有名称以"B"起始的元素
     <AAA>
          <BCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </BCC>
          <DDB>
               <BBB/>
               <BBB/>
          </DDB>
          <BEC>
               <CCC/>
               <DBD/>
          </BEC>
     </AAA> 回页首 //*[contains(name(),'C')]选择所有名称包含"C"的元素
     <AAA>
          <BCC>
               <BBB/>
               <BBB/>
               <BBB/>
          </BCC>
          <DDB>
               <BBB/>
               <BBB/>
          </DDB>
          <BEC>
               <CCC/>
               <DBD/>
          </BEC>
     </AAA> 回页首

string-length函数返回字符串的字符数,你应该用&lt;替代<, 用&gt;代替>

//*[string-length(name()) = 3]选择名字长度为3的元素
     <AAA>
          <Q/>
          <SSSS/>
          <BB/>
          <CCC/>
          <DDDDDDDD/>
          <EEEE/>
     </AAA> 回页首 //*[string-length(name()) < 3]选择名字长度小于3的元素
     <AAA>
          <Q/>
          <SSSS/>
          <BB/>
          <CCC/>
          <DDDDDDDD/>
          <EEEE/>
     </AAA> 回页首 //*[string-length(name()) > 3]选择名字长度大于3的元素
     <AAA>
          <Q/>
          <SSSS/>
          <BB/>
          <CCC/>
          <DDDDDDDD/>
          <EEEE/>
     </AAA> 回页首

多个路径可以用分隔符 | 合并在一起

//CCC | //BBB选择所有的CCC和BBB元素
     <AAA>
          <BBB/>
          <CCC/>
          <DDD>
               <CCC/>
          </DDD>
          <EEE/>
     </AAA> 回页首 /AAA/EEE | //BBB选择所有的BBB元素和所有是AAA的子元素的EEE元素
     <AAA>
          <BBB/>
          <CCC/>
          <DDD>
               <CCC/>
          </DDD>
          <EEE/>
     </AAA> 回页首 /AAA/EEE | //DDD/CCC | /AAA | //BBB可以合并的路径数目没有限制
     <AAA>
          <BBB/>
          <CCC/>
          <DDD>
               <CCC/>
          </DDD>
          <EEE/>
     </AAA> 回页首

child轴(axis)包含上下文节点的子元素, 作为默认的轴,可以忽略不写.

/AAA等价于 /child::AAA
     <AAA>
          <BBB/>
          <CCC/>
     </AAA> 回页首 /child::AAA等价于/AAA
     <AAA>
          <BBB/>
          <CCC/>
     </AAA> 回页首 /AAA/BBB等价于/child::AAA/child::BBB
     <AAA>
          <BBB/>
          <CCC/>
     </AAA> 回页首 /child::AAA/child::BBB等价于/AAA/BBB
     <AAA>
          <BBB/>
          <CCC/>
     </AAA> 回页首 /child::AAA/BBB二者都可以被合并
     <AAA>
          <BBB/>
          <CCC/>
     </AAA> 回页首

descendant (后代)轴包含上下文节点的后代,一个后代是指子节点或者子节点的子节点等等, 因此descendant轴不会包含属性和命名空间节点.

/descendant::*选择文档根元素的所有后代.即所有的元素被选择
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首 /AAA/BBB/descendant::*选择/AAA/BBB的所有后代元素
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首 //CCC/descendant::*选择在祖先元素中有CCC的所有元素
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首 //CCC/descendant::DDD选择所有以CCC为祖先元素的DDD元素
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首

parent轴(axis)包含上下文节点的父节点, 如果有父节点的话

//DDD/parent::*选择DDD元素的所有父节点
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首

ancestor轴(axis)包含上下节点的祖先节点, 该祖先节点由其上下文节点的父节点以及父节点的父节点等等诸如此类的节点构成,所以ancestor轴总是包含有根节点,除非上下文节点就是根节点本身.

/AAA/BBB/DDD/CCC/EEE/ancestor::*选择一个绝对路径上的所有节点
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首 //FFF/ancestor::*选择FFF元素的祖先节点
     <AAA>
          <BBB>
               <DDD>
                    <CCC>
                         <DDD/>
                         <EEE/>
                    </CCC>
               </DDD>
          </BBB>
          <CCC>
               <DDD>
                    <EEE>
                         <DDD>
                              <FFF/>
                         </DDD>
                    </EEE>
               </DDD>
          </CCC>
     </AAA> 回页首

following-sibling轴(axis)包含上下文节点之后的所有兄弟节点

/AAA/BBB/following-sibling::* 
     <AAA>
          <BBB>
               <CCC/>
               <DDD/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //CCC/following-sibling::* 
     <AAA>
          <BBB>
               <CCC/>
               <DDD/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

preceding-sibling 轴(axis)包含上下文节点之前的所有兄弟节点

/AAA/XXX/preceding-sibling::* 
     <AAA>
          <BBB>
               <CCC/>
               <DDD/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //CCC/preceding-sibling::* 
     <AAA>
          <BBB>
               <CCC/>
               <DDD/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

following轴(axis)包含同一文档中按文档顺序位于上下文节点之后的所有节点, 除了祖先节点,属性节点和命名空间节点

/AAA/XXX/following::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
                    <DDD>
                         <EEE/>
                    </DDD>
               </ZZZ>
               <FFF>
                    <GGG/>
               </FFF>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //ZZZ/following::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
                    <DDD>
                         <EEE/>
                    </DDD>
               </ZZZ>
               <FFF>
                    <GGG/>
               </FFF>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

following轴(axis)包含同一文档中按文档顺序位于上下文节点之前的所有节点, 除了祖先节点,属性节点和命名空间节点

/AAA/XXX/preceding::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //GGG/preceding::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

descendant-or-self 轴(axis)包含上下文节点本身和该节点的后代节点

/AAA/XXX/descendant-or-self::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //CCC/descendant-or-self::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

ancestor-or-self 轴(axis)包含上下文节点本身和该节点的祖先节点

/AAA/XXX/DDD/EEE/ancestor-or-self::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //GGG/ancestor-or-self::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ>
                    <DDD/>
               </ZZZ>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <DDD/>
                    <CCC/>
                    <FFF/>
                    <FFF>
                         <GGG/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首

ancestor, descendant, following, preceding 和self轴(axis)分割了XML文档(忽略属性节点和命名空间节点), 不能交迭, 而一起使用则包含所有节点

//GGG/ancestor::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <FFF>
                         <HHH/>
                         <GGG>
                              <JJJ>
                                   <QQQ/>
                              </JJJ>
                              <JJJ/>
                         </GGG>
                         <HHH/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //GGG/descendant::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <FFF>
                         <HHH/>
                         <GGG>
                              <JJJ>
                                   <QQQ/>
                              </JJJ>
                              <JJJ/>
                         </GGG>
                         <HHH/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //GGG/following::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <FFF>
                         <HHH/>
                         <GGG>
                              <JJJ>
                                   <QQQ/>
                              </JJJ>
                              <JJJ/>
                         </GGG>
                         <HHH/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //GGG/preceding::* 
     <AAA>
          <BBB>
               <CCC/>
               <ZZZ/>
          </BBB>
          <XXX>
               <DDD>
                    <EEE/>
                    <FFF>
                         <HHH/>
                         <GGG>
                              <JJJ>
                                   <QQQ/>
                              </JJJ>
                              <JJJ/>
                         </GGG>
                         <HHH/>
                    </FFF>
               </DDD>
          </XXX>
          <CCC>
               <DDD/>
          </CCC>
     </AAA> 回页首 //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> 回页首 //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> 回页首

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> 回页首 //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> 回页首 //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> 回页首

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posted @ 2006-10-11 10:18 Think 阅读(10478) 评论(17)  编辑 收藏 网摘 所属分类: XML