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Html/xml/xpath Foundation

Source: Internet
Author: User
Tags xpath
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HTML Hypertext Markup Language

Right-click on Web page → view source file/View source code

HTML BASIC Structure

......

<body> document body, display on browser

......

</body>

use tags in head

<tittle></tittle> document titles are displayed in the title bar

<script></script>

<style></style> referencing CSS Styles

XML Extensible Markup Language

Http://www.yesky.com/imagesnew/software/html/index.html

a language for finding information in an XPath XML document

/Slash Start path instance 1

<AAA>

<BBB/>

<CCC/>

<DDD>

<BBB/>

</DDD>

<CCC/>

</AAA> XPath expression:/aaa Select root element AAA

/Slash Start path instance 2

<AAA>

<BBB/>

　　<CCC/>

<DDD>

<BBB/>

</DDD>

　　<CCC/>

</AAA> XPath expression:/AAA/CCC Select the sub-element of AAA CCC

/Slash Start path instance 3

<AAA>

<BBB/>

<CCC/>

<DDD>

　　　　 <BBB/>

</DDD>

<CCC/>

</AAA> XPath expression:/aaa/ddd/bbb Select child element of AAA DDD element BBB

Start path instance with double slash 1

<AAA>

　　<BBB/>

<CCC/>

　　<BBB/>

<DDD>

　　　　<BBB/>

</DDD>

<CCC/>

<DDD>

　　　　<BBB/>

　　　　<BBB/>

</DDD>

<CCC/>

</AAA> XPath expression://bbb selects all BBB elements

Start path instance with double Slash 2

<AAA>

<BBB/>

<CCC/>

<BBB/>

<DDD>

　　　　<BBB/>

</DDD>

<CCC/>

<DDD>

　　　　<BBB/>

　　　　<BBB/>

</DDD>

<CCC/>

</AAA> XPath expression://DDD/BBB Select all the parent elements are the BBB elements of DDD

* Start path instance with asterisk 1

<AAA>

<CCC/>

<DDD>

　　　　　　 <BBB/>

　　　　　　<BBB/>

<EEE/>　　　　　　  

　　　　　　<EEE/>

</DDD>

<CCC/>

</AAA> XPath expression:/aaa/ccc/ddd/* Select all the paths that are attached to the/aaa/ccc/ddd/element

* Start path instance with asterisk 2

<AAA>

<XXX/>

<DDD>

　　　　　　 <BBB/>

　　　　　　<BBB/>

<EEE/>

</DDD>

<XXX/>

<CCC/>

<BBB>

　　　　　　 <BBB/>

<BBB/>

<BBB/> 　　　　　　

<BBB/>

<CCC/>

</AAA> XPath expression:/*/*/*/bbb selects all BBB elements with 3 ancestor elements

* Start path instance with asterisk 3

<AAA>                  

　　<CCC/>

　　　　</DDD>

　　<CCC/>

</AAA> XPath expression://* Select all elements

[] Use square brackets to qualify an element instance 1

<AAA>

　　<BBB/>

<BBB/>

<BBB/>

</AAA> XPath expression:/aaa/bbb[1] Select the first BBB child element of AAA

[] Use square brackets to qualify an element instance 2

<AAA>

<BBB/>

<BBB/>

　　<BBB/>

</AAA> XPath expression:/aaa/bbb[last ()] Select the last BBB child element of AAA

@ Specify attribute instance by @ 1

<AAA>

<BBB id= "B1"/>

<BBB id= "B2"/>

<BBB name= "BBB"/>

<BBB/>

</AAA> XPath expression://@id Select all ID attributes (note that the attributes of the element are selected, not the element)

@ Specify attribute instance by @ 2

<AAA>

<BBB id= "B1"/>

<BBB id= "B2"/>

<BBB name= "BBB"/>

<BBB/>

</AAA> XPath expression://bbb[@id] Selects the BBB element for all ID attributes (//bbb[@name] selects the BBB element for all name attributes)

@ Specify attribute instance by @ 3

<AAA>

<BBB id= "B1"/>

<BBB id= "B2"/>

<BBB name= "BBB"/>

<BBB/>

</AAA> XPath expression://bbb[@*] Select the BBB element with any attribute

@ Specify attribute instance by @ 4

<AAA>

<BBB id= "B1"/>

<BBB id= "B2"/>

<BBB name= "BBB"/>

　　<BBB/>

</AAA> XPath expression://bbb[not (@*)] Select the BBB element with no attributes

Using attribute values as selection criteria 1

<AAA>

<BBB id= "B1"/>

<BBB id= "B2"/>

<BBB name= "BBB"/>

<BBB/>

</AAA> XPath expression://bbb[@id = ' B1 ') Select the BBB element containing the attribute id= ' B1 '

| using the delimiter "|" Merging multiple path instances 1

<AAA>

　　<BBB/>

<CCC/>

<DDD>

　　　　 <CCC/>

</DDD>

　　<EEE/>

</AAA> XPath expression:/aaa/eee|//ddd/ccc| AAA|//BBB Merge No Limits

Http:www.w3school.com.cn/xpath/index.asp

Html/xml/xpath Foundation

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