C#操作Xml:XSLT语法 在.net中使用XSLT转换xml文档示例

XSL即可扩展的样式表文件。 可以格式化xml的显示,也可以将xml转换成需要的另一种格式。

学习XSL必须熟悉XPath。XSL和XPath一样简单强大,容易学习。

1. XSL既然可以格式化xml的显示样式,我们先来看如何在xml中引用xsl文件

如下代码示例:

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

<?xml-stylesheet type="text/xsl" href="url.xsl"?>

只需在xml文件的文档声明后面添加<?xml-stylesheet type=”text/xsl” href=”url.xsl”?>即可

2. XSL的格式

XSL也是一个标准的xml文件,它以xml文档声明开始,根元素必须是xsl:styleshee,同时根元素必须有version属性指定xsl的版本,和xmlns:xsl=” http://www.w3.org/1999/XSL/Transform”指定xsl命名空间,如下示例

<?xml version="1.0" encoding="encoding”?>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

3. Xsl要点 如下示例xml

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<?xml version="1.0" encoding="utf-8" ?>
<?xml-stylesheet  type="text/xsl" href="pets-templates.xsl"?>
<pets>
  <pig color="blue" weight="100">
    <price>100</price>
    <desc>this is a blue pig</desc>
  </pig>
  <cat color="red" weight="9">
    <price>80</price>
    <desc>this is a red cat</desc>
  </cat>
  <dog color="green" weight="15">
    <price>80</price>
    <desc>this is a green dog</desc>
  </dog>
  <cat color="green" weight="15">
    <price>80</price>
    <desc>this is a green cat</desc>
  </cat>
 
 
  <dog color="blue" weight="10">
    <price>100</price>
    <desc>this is a blue dog</desc>
  </dog>
  <dog color="red" weight="9">
    <price>80</price>
    <desc>this is a red dog</desc>
  </dog>
</pets>

上面的xml在通过xsl格式化之后的显示效果如下:

C#操作Xml:XSLT语法 在.net中使用XSLT转换xml文档示例

1) xsl:template定义匹配节点的转换模板,属性match=”xpath expression”用来定义模板匹配的元素

如下定义匹配根节点的模板

<xsl:template match=”/”>

</xsl:template>

2) xsl:for-each循环显示select=”xpath expression”选择节点的转换 (类似编程语言中的foreach语句),

如下示例,选择了pets下面的子元素,并循环显示子元素的几点名字:

<xsl:for-each select=”/pets/*”>

<xsl:value-of select=”name()”/>

</xsl:for-each>

3) xsl:if 元素条件显示节点(类似编程语言中的if语句)注意小于号大于号要分别用&lt;和&gt;替代

<xsl:if test=”@weight &lt; 10”>

<i>its weight is less than 10 km</i>

</xsl:if>

4) xsl:choose 多分支条件显示 (类似编程语言中的switch语句)

<xsl:choose >

 <xsl:when test=”name() = ‘pig’”>

<i>this is a pig</i>

 </xsl:when>

<xsl:otherwise>

  <i>this is not a pig</i>

</xsl:otherwise>

</xsl:choose>

5) xsl:value-of 显示选择节点或者属性的值

选择子节点price

<xsl:value-of select=”pets/*/price”/>

选择属性weight

<xsl:value-of select=”pets/*/@weight”/>

6) xsl:attribute 构造xml节点的属性

用来向节点添加属性,例如:

<font>

<xsl:attribute name=”color”><xsl:value-of select=”pets/*/@color”/></xsl:attribute>

</font>

将输出<font color=”red”></font>

7) xsl:apply-templates 应用模板

 如果xml文件结构比较复杂,可以定义多个template,然后使用<xsl:apply-templates>标签应用模板,xsl:apply-templates 可以指定属性select=”xpath”来选择应用的模板,或者不指定select表示选择当前节点的模板。

 请看下面示例xslt文件pets-templates.xsl

完整的示例xsl文件:pets.xsl
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<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
      xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <html>
      <head>
        <META http-equiv="Content-Type" content="text/html; charset=utf-8"/>
        <title>lovely pets</title>
        <style type="text/css">
          ul{margin:10px 0 10px 0;padding:0;width:400px;text-align:left;}
          li{height:60px;display:block;list-style:none;padding:4px;border:1px solid #f0f0f0;margin:5px;}
        </style>
      </head>
      <body>
        <center>
        <h1>lovely pets</h1>
        <ul>
          <xsl:for-each select="pets/*">
            <li>
              <img align="right">
                <xsl:choose>
                  <xsl:when test="name() = ‘dog‘">
                    <xsl:attribute name="src">http://estar-tv.com/images/comprofiler/gallery/dog.gif</xsl:attribute>
                  </xsl:when>
                  <xsl:when test="name() = ‘pig‘">
                    <xsl:attribute name="src">http://www.icosky.com/icon/thumbnails/Animal/Farm/Pig%20Icon.jpg</xsl:attribute>
                  </xsl:when>
                  <xsl:otherwise>
                    <xsl:attribute name="src">http://farm1.static.flickr.com/14/buddyicons/22211409@N00.jpg?1143660418</xsl:attribute>
                  </xsl:otherwise>
                </xsl:choose>
              </img>
              <font>
                <xsl:attribute name="face">Courier</xsl:attribute>
                <xsl:attribute name="color">
                  <xsl:value-of select="@color"/>
                </xsl:attribute>
                <xsl:value-of select="name()"/>
              </font> said: "<xsl:value-of select="desc"/>"
              weight:<xsl:value-of select="@weight"/>
 
              <xsl:if test="@weight < 10">
                <p>
                  <i>its weight is less than 10 km</i>
                </p>
              </xsl:if>
 
 
            </li>
          </xsl:for-each>
        </ul>
        </center>
      </body>
    </html>
  </xsl:template>
</xsl:stylesheet>

完整示例文件 pets-templates.xsl:

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<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
      xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <html>
      <head>
        <META http-equiv="Content-Type" content="text/html; charset=utf-8"/>
        <title>lovely pets</title>
        <style type="text/css">
          ul{margin:10px 0 10px 0;padding:0;width:400px;text-align:left;}
          li{height:60px;display:block;list-style:none;padding:4px;border:1px solid #f0f0f0;margin:5px;}
        </style>
      </head>
      <body>
        <center>
          <h1>lovely pets</h1>
          <ul>
            <xsl:apply-templates select="pets" />
          </ul>
        </center>
      </body>
    </html>
  </xsl:template>
 
  <xsl:template match="pets">   
    <xsl:apply-templates select="dog"></xsl:apply-templates>
    <xsl:apply-templates select="pig"></xsl:apply-templates>
    <xsl:apply-templates select="cat"></xsl:apply-templates>
  </xsl:template>
 
  <xsl:template match="dog">
    <xsl:for-each select=".">
      <li>
        <img align="right">
          <xsl:attribute name="src">http://estar-tv.com/images/comprofiler/gallery/dog.gif</xsl:attribute>         
        </img>
        <font>
          <xsl:attribute name="face">Courier</xsl:attribute>
          <xsl:attribute name="color">
            <xsl:value-of select="@color"/>
          </xsl:attribute>
          dog
        </font> said: "<xsl:value-of select="desc"/>"
        weight:<xsl:value-of select="@weight"/>
 
        <xsl:if test="@weight < 10">
          <p>
            <i>its weight is less than 10 km</i>
          </p>
        </xsl:if>
      </li>
    </xsl:for-each>
  </xsl:template>
 
 
 
  <xsl:template match="pig">
    <xsl:for-each select=".">
      <li>
        <img align="right">
          <xsl:attribute name="src">http://www.icosky.com/icon/thumbnails/Animal/Farm/Pig%20Icon.jpg</xsl:attribute>
        </img>
        <font>
          <xsl:attribute name="face">Courier</xsl:attribute>
          <xsl:attribute name="color">
            <xsl:value-of select="@color"/>
          </xsl:attribute>
          pig
        </font> said: "<xsl:value-of select="desc"/>"
        weight:<xsl:value-of select="@weight"/>
 
        <xsl:if test="@weight < 10">
          <p>
            <i>its weight is less than 10 km</i>
          </p>
        </xsl:if>
      </li>
    </xsl:for-each>
  </xsl:template>
 
 
  <xsl:template match="cat">
    <xsl:for-each select=".">
      <li>
        <img align="right">
          <xsl:attribute name="src">http://farm1.static.flickr.com/14/buddyicons/22211409@N00.jpg?1143660418</xsl:attribute>
        </img>
        <font>
          <xsl:attribute name="face">Courier</xsl:attribute>
          <xsl:attribute name="color">
            <xsl:value-of select="@color"/>
          </xsl:attribute>
          cat
        </font> said: "<xsl:value-of select="desc"/>"
        weight:<xsl:value-of select="@weight"/>
 
        <xsl:if test="@weight < 10">
          <p>
            <i>its weight is less than 10 km</i>
          </p>
        </xsl:if>
      </li>
    </xsl:for-each>
  </xsl:template>
   
</xsl:stylesheet>

在c#.net中使用XslCompiledTransform转换xml文档,XslTransform也可以使用,但是这个类已经被微软标记为过时,最好不要再用了,如下代码示例:

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Xml;
 
namespace UseXslt
{
    class Program
    {
        static void Main(string[] args)
        {
            //声明XslTransform类实例
            System.Xml.Xsl.XslCompiledTransform trans = new System.Xml.Xsl.XslCompiledTransform();
 
            string xsltFile = @"X:\about.net\System.Xml\example\pets.xsl";
            using (StreamReader rdr = new StreamReader(xsltFile))
            {
                using (XmlReader xmlRdr = XmlReader.Create(rdr))
                {
                    //载入xsl文件
                    trans.Load(xmlRdr);
                }
            }
            string inputFile = @"X:\about.net\System.Xml\example\pets.xml";
            string outputFile = @"X:\about.net\System.Xml\example\pets-out.htm";
            //转化源文件输出到输出文件outputFile
            trans.Transform(inputFile, outputFile);
        }
    }
}

 

有一点需要注意,使用XslCompiledTransform转换出来的文件,是一个html格式的,这个类会自动在html的head标签中添加一个未关闭的meta标签 <META http-equiv="Content-Type" content="text/html; charset=utf-8">;微软帮我们想的太多了。

Xslt还可以指定参数,定义变量,有关这些方面请查看相关文档。

C#处理Xml的相关随笔:

C#操作Xml:XSLT语法 在.net中使用XSLT转换xml文档示例

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