XPath语法 在C#中使用XPath示例

<?

xml

version

=

"1.0"

encoding

=

"utf-8"

?>

<

pets

>

<

cat

color

=

"black"

weight

=

"10"

>

<

price

>100</

price

>

<

desc

>this is a black cat</

desc

>

</

cat

>

<

cat

color

=

"white"

weight

=

"9"

>

<

price

>80</

price

>

<

desc

>this is a white cat</

desc

>

</

cat

>

<

cat

color

=

"yellow"

weight

=

"15"

>

<

price

>80</

price

>

<

desc

>this is a yellow cat</

desc

>

</

cat

>

<

dog

color

=

"black"

weight

=

"10"

>

<

price

>100</

price

>

<

desc

>this is a black dog</

desc

>

</

dog

>

<

dog

color

=

"white"

weight

=

"9"

>

<

price

>80</

price

>

<

desc

>this is a white dog</

desc

>

</

dog

>

<

dog

color

=

"yellow"

weight

=

"15"

>

<

price

>80</

price

>

<

desc

>this is a yellow dog</

desc

>

</

dog

>

</

pets

>

using

System;

using

System.Collections.Generic;

using

System.Linq;

using

System.Text;

using

System.Xml.XPath;

using

System.Xml;

namespace

UseXPathDotNet

{

class

Program

{

static

void

Main(

string

[] args)

{

UseXPathWithXPathDocument();

UseXPathWithXmlDocument();

Console.Read();

}

static

void

UseXPathWithXmlDocument()

{

XmlDocument doc =

new

XmlDocument();

doc.Load(

"http://www.cnblogs.com/yukaizhao/rss"

);

//使用xPath选择需要的节点

XmlNodeList nodes = doc.SelectNodes(

"/rss/channel/item[position()<=10]"

);

foreach

(XmlNode item

in

nodes)

{

string

title = item.SelectSingleNode(

"title"

).InnerText;

string

url = item.SelectSingleNode(

"link"

).InnerText;

Console.WriteLine(

"{0} = {1}"

, title, url);

}

}

static

void

UseXPathWithXPathDocument()

{

XPathDocument doc =

new

XPathDocument(

"http://www.cnblogs.com/yukaizhao/rss"

);

XPathNavigator xPathNav = doc.CreateNavigator();

//使用xPath取rss中最新的10条随笔

XPathNodeIterator nodeIterator = xPathNav.Select(

"/rss/channel/item[position()<=10]"

);

while

(nodeIterator.MoveNext())

{

XPathNavigator itemNav = nodeIterator.Current;

string

title = itemNav.SelectSingleNode(

"title"

).Value;

string

url = itemNav.SelectSingleNode(

"link"

).Value;

Console.WriteLine(

"{0} = {1}"

,title,url);

}

}

}

}

using

System;

using

System.Collections.Generic;

using

System.Linq;

using

System.Text;

using

System.IO;

using

System.Xml;

namespace

UseXPath1

{

class

Program

{

static

void

Main(

string

[] args)

{

string

xml =

@"<?xml version=""1.0"" encoding=""utf-8"" ?>

<pets>

<cat color=""black"" weight=""10"" count=""4"">

<price>100</price>

<desc>this is a black cat</desc>

</cat>

<cat color=""white"" weight=""9"" count=""5"">

<price>80</price>

<desc>this is a white cat</desc>

</cat>

<cat color=""yellow"" weight=""15"" count=""1"">

<price>110</price>

<desc>this is a yellow cat</desc>

</cat>

<dog color=""black"" weight=""10"" count=""7"">

<price>114</price>

<desc>this is a black dog</desc>

</dog>

<dog color=""white"" weight=""9"" count=""4"">

<price>80</price>

<desc>this is a white dog</desc>

</dog>

<dog color=""yellow"" weight=""15"" count=""15"">

<price>80</price>

<desc>this is a yellow dog</desc>

</dog>

<pig color=""white"" weight=""100"" count=""2"">

<price>8000</price>

<desc>this is a white pig</desc>

</pig>

</pets>"

;

using

(StringReader rdr =

new

StringReader(xml))

{

XmlDocument doc =

new

XmlDocument();

doc.Load(rdr);

//取所有pets节点下的dog字节点

XmlNodeList nodeListAllDog = doc.SelectNodes(

"/pets/dog"

);

//所有的price节点

XmlNodeList allPriceNodes = doc.SelectNodes(

"//price"

);

//取最后一个price节点

XmlNode lastPriceNode = doc.SelectSingleNode(

"//price[last()]"

);

//用双点号取price节点的父节点

XmlNode lastPriceParentNode = lastPriceNode.SelectSingleNode(

".."

);

//选择weight*count=40的所有动物，使用通配符*

XmlNodeList nodeList = doc.SelectNodes(

"/pets/*[@weight*@count=40]"

);

//选择除了pig之外的所有动物,使用name()函数返回节点名字

XmlNodeList animalsExceptPigNodes = doc.SelectNodes(

"/pets/*[name() != 'pig']"

);

//选择价格大于100而不是pig的动物

XmlNodeList priceGreaterThan100s = doc.SelectNodes(

"/pets/*[price div @weight >10 and name() != 'pig']"

);

foreach

(XmlNode item

in

priceGreaterThan100s)

{

Console.WriteLine(item.OuterXml);

}

//选择第二个dog节点

XmlNode theSecondDogNode = doc.SelectSingleNode(

"//dog[position() = 2]"

);

//使用xpath ，axes 的 parent 取父节点

XmlNode parentNode = theSecondDogNode.SelectSingleNode(

"parent::*"

);

//使用xPath选择第二个dog节点前面的所有dog节点

XmlNodeList dogPresibling = theSecondDogNode.SelectNodes(

"preceding::dog"

);

//取文档的所有子孙节点price

XmlNodeList childrenNodes = doc.SelectNodes(

"descendant::price"

);

}

Console.Read();

}

}

}