Xslt 简明教程

XSLT Quick Guide

XSLT Overview

XSL

在学习 XSLT 之前，我们应该首先了解 XSL，它代表 E*X*tensible *S*tylesheet *L*anguage。它类似于 XML，就像 CSS 与 HTML 类似。

Before learning XSLT, we should first understand XSL which stands for E*X*tensible *S*tylesheet *L*anguage. It is similar to XML as CSS is to HTML.

Need for XSL

对于 HTML 文档，标签是预定义的，例如表、div 和 span；而且浏览器知道如何为它们添加样式，并使用 CSS 样式显示它们。但对于 XML 文档，标签未预先定义。为了理解和设置 XML 文档的样式，万维网联盟 (W3C) 开发了 XSL，它可以作为基于 XML 的样式化语言。XSL 文档指定浏览器应该如何呈现 XML 文档。

In case of HTML document, tags are predefined such as table, div, and span; and the browser knows how to add style to them and display those using CSS styles. But in case of XML documents, tags are not predefined. In order to understand and style an XML document, World Wide Web Consortium (W3C) developed XSL which can act as XML based Stylesheet Language. An XSL document specifies how a browser should render an XML document.

以下是 XSL 的主要部分 −

Following are the main parts of XSL −

XSLT − used to transform XML document into various other types of document.
XPath − used to navigate XML document.
XSL-FO − used to format XML document.

What is XSLT

XSLT（可扩展样式表语言转换）提供了一种将 XML 数据从一种格式自动转换为另一种格式的功能。

XSLT, Extensible Stylesheet Language Transformations, provides the ability to transform XML data from one format to another automatically.

How XSLT Works

XSLT 样式表用于定义要应用于目标 XML 文档的转换规则。XSLT 样式表以 XML 格式编写。XSLT 处理器获取 XSLT 样式表并将其转换规则应用于目标 XML 文档，然后生成 XML、HTML 或文本格式的格式化文档。此格式化文档随后由 XSLT 格式化程序用于生成要向最终用户显示的实际输出。

An XSLT stylesheet is used to define the transformation rules to be applied on the target XML document. XSLT stylesheet is written in XML format. XSLT Processor takes the XSLT stylesheet and applies the transformation rules on the target XML document and then it generates a formatted document in the form of XML, HTML, or text format. This formatted document is then utilized by XSLT formatter to generate the actual output which is to be displayed to the end-user.

Advantages

以下是使用 XSLT 的优势：

Here are the advantages of using XSLT −

Independent of programming. Transformations are written in a separate xsl file which is again an XML document.
Output can be altered by simply modifying the transformations in xsl file. No need to change any code. So Web designers can edit the stylesheet and can see the change in the output quickly.

XSLT Syntax

假设我们有以下样本 XML 文件 students.xml，需要将其转换为格式良好的 HTML 文档。

Let’s suppose we have the following sample XML file, students.xml, which is required to be transformed into a well-formatted HTML document.

students.xml

<?xml version = "1.0"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

我们需要为上述 XML 文档定义一个 XSLT 样式表文档，以满足以下条件：

We need to define an XSLT style sheet document for the above XML document to meet the following criteria −

Page should have a title Students.
Page should have a table of student details.
Columns should have following headers: Roll No, First Name, Last Name, Nick Name, Marks
Table must contain details of the students accordingly.

Step 1: Create XSLT document

创建 XSLT 文档以满足上述要求，将其命名为 students.xsl，并保存在 students.xml 所在的同一位置。

Create an XSLT document to meet the above requirements, name it as students.xsl and save it in the same location where students.xml lies.

students.xsl

<?xml version = "1.0" encoding = "UTF-8"?>
<!-- xsl stylesheet declaration with xsl namespace:
Namespace tells the xlst processor about which
element is to be processed and which is used for output purpose only
-->
<xsl:stylesheet version = "1.0"
xmlns:xsl = "http://www.w3.org/1999/XSL/Transform">
<!-- xsl template declaration:
template tells the xlst processor about the section of xml
document which is to be formatted. It takes an XPath expression.
In our case, it is matching document root element and will
tell processor to process the entire document with this template.
-->
   <xsl:template match = "/">
      <!-- HTML tags
         Used for formatting purpose. Processor will skip them and browser
            will simply render them.
      -->

      <html>
         <body>
            <h2>Students</h2>

            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <!-- for-each processing instruction
               Looks for each element matching the XPath expression
               -->

               <xsl:for-each select="class/student">
                  <tr>
                     <td>
                        <!-- value-of processing instruction
                        process the value of the element matching the XPath expression
                        -->
                        <xsl:value-of select = "@rollno"/>
                     </td>

                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>

                  </tr>
               </xsl:for-each>

            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Step 2: Link the XSLT Document to the XML Document

使用以下 xml-stylesheet 标记更新 student.xml 文档。将 href 的值设置为 students.xsl

Update student.xml document with the following xml-stylesheet tag. Set href value to students.xsl

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
...
</class>

Step 3: View the XML Document in Internet Explorer

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

Output

XSLT <template>

<> 定义了一种方法，用于重新使用模板，以便为特定类型/上下文的节点生成所需的输出。

<xsl:template> defines a way to reuse templates in order to generate the desired output for nodes of a particular type/context.

Declaration

以下是元素的语法声明。

Following is the syntax declaration of <xsl:template> element.

<xsl:template
   name = Qname
   match = Pattern
   priority = number
   mode = QName >
</xsl:template>

Attributes

Sr.No	Name & Description
1	name Name of the element on which template is to be applied.
2	match Pattern which signifies the element(s) on which template is to be applied.
3	priority Priority number of a template. Matching template with low priority is not considered in from in front of high priority template.
4	mode Allows element to be processed multiple times to produce a different result each time.

Elements

Number of occurrences

Unlimited

Parent elements

xsl:stylesheet, xsl:transform

Child elements

xsl:apply-imports,xsl:apply-templates,xsl:attribute, xsl:call-template, xsl:choose, xsl:comment, xsl:copy, xsl:copy-of, xsl:element, xsl:fallback, xsl:for-each, xsl:if, xsl:message, xsl:number, xsl:param, xsl:processing-instruction, xsl:text, xsl:value-of, xsl:variable, output elements

Demo Example

此模板规则具有用于识别元素的模式，并以表格格式生成输出。

This template rule has a pattern that identifies <student> elements and produces an output in a tabular format.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students_imports.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">
                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <value-of>

<xsl:value-of>标签将所选节点的值作为文本放置在XPath表达式中。

<xsl:value-of> tag puts the value of the selected node as per XPath expression, as text.

Declaration

以下是 <xsl:value-of> 元素的语法声明。

Following is the syntax declaration of <xsl:value-of> element.

<xsl:value-of
   select = Expression
   disable-output-escaping = "yes" | "no" >
</xsl:value-of>

Attributes

Sr.No

Name & Description

Select XPath Expression to be evaluated in current context.

disable-outputescaping Default-"no". If "yes", output text will not escape xml characters from text.

Elements

Number of Occurrences

Unlimited

Parent elements

xsl:attribute, xsl:comment, xsl:copy, xsl:element, xsl:fallback, xsl:for-each, xsl:if, xsl:message, xsl:otherwise, xsl:param, xsl:processing instruction, xsl:template, xsl:variable, xsl:when, xsl:with-param, output elements

Child elements

None

Demo Example

此示例创建带有其属性 rollno 及其子级<firstname>、<lastname>、<nickname>和<marks>的<student>元素的表。

This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks>.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">
                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>

            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Verify the output

XSLT <for-each>

<xsl:for-each> 标记对每个节点重复应用模板。

<xsl:for-each> tag applies a template repeatedly for each node.

Declaration

以下是 <xsl:for-each> 元素的语法声明

Following is the syntax declaration of <xsl:for-each> element

<xsl:for-each
   select = Expression >
</xsl:for-each>

Attributes

Sr.No

Name & Description

Select XPath Expression to be evaluated in current context to determine the set of nodes to be iterated.

Elements

Number of Occurrences

Unlimited

Parent elements

xsl:attribute, xsl:comment, xsl:copy, xsl:element, xsl:fallback, xsl:foreach, xsl:if, xsl:message, xsl:otherwise, xsl:param, xsl:processinginstruction, xsl:template, xsl:variable, xsl:when, xsl:with-param, output elements.

Child elements

xsl:apply-imports, xsl:apply-templates, xsl:attribute, xsl:call-template, xsl:choose, xsl:comment, xsl:copy, xsl:copy-of, xsl:element, xsl:fallback, xsl:for-each, xsl:if, xsl:message, xsl:number, xsl:processing-instruction, xsl:sort, xsl:text, xsl:value-of, xsl:variable.

Demo Example

此示例通过迭代每个 <student> 元素，以此元素的 rollno 属性及其子元素 <firstname>, <lastname>, <nickname> 和 <marks> 创建一个表格。

This example creates a table of <student> element with its attribute rollno and its child <firstname>,<lastname><nickname> and <marks> by iterating over each student.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>

            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <sort>

<xsl:sort> 标记指定节点的排序条件。

<xsl:sort> tag specifies a sort criteria on the nodes.

Declaration

以下是 <xsl:sort> 元素的语法声明。

Following is the syntax declaration of <xsl:sort> element.

<xsl:sort
   select = string-expression
   lang = { nmtoken }
   data-type = { "text" | "number" | QName }
   order = { "ascending" | "descending" }
   case-order = { "upper-first" | "lower-first" } >
</xsl:sort>

Attributes

Sr.No	Name & Description
1	select Sorting key of the node.
2	lang Language alphabet used to determine sort order.
3	data-type Data type of the text.
4	order Sorting order. Default is "ascending".
5	case-order Sorting order of string by capitalization. Default is "upper-first".

Elements

Number of occurrences

Unlimited

Parent elements

xsl:apply-templates, xsl:for-each

Child elements

None

Demo Example

此示例通过迭代每个学生，并按照姓氏对他们进行排序，来创建带有其属性 rollno 及其子属性 <firstname>、<lastname>、<nickname> 和 <marks> 的 <table> 元素。

This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student sort them by first name.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <xsl:sort select = "firstname"/>
                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <if>

<xsl:if> 标记指定对节点的内容执行条件测试。

<xsl:if> tag specifies a conditional test against the content of nodes.

Declaration

以下是 <xsl:if> 元素的语法声明。

Following is the syntax declaration of <xsl:if> element.

<xsl:if
  test = boolean-expression >
</xsl:if>

Attributes

Sr.No

Name & Description

test The condition in the xml data to test.

Elements

Number of Occurrences

Unlimited

Parent elements

xsl:attribute, xsl:comment, xsl:copy, xsl:element, xsl:fallback, xsl:for-each, xsl:if, xsl:message, xsl:otherwise, xsl:param, xsl:processing-instruction, xsl:template, xsl:variable, xsl:when, xsl:with-param, output elements

Child elements

xsl:apply-templates, xsl:attribute, xsl:call-template, xsl:choose, xsl:comment, xsl:copy, xsl:copy-of, xsl:element, xsl:for-each, xsl:if, xsl:processing-instruction, xsl:text, xsl:value-of, xsl:variable, output elements

Demo Example

此示例通过迭代每个学生来创建带其属性 rollno 及其子属性 <firstname>、<lastname>、<nickname> 和 <marks> 的 <table> 元素。它检查分数是否大于 90，然后打印学生的详细信息。

This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student. It checks marks to be greater than 90 and then prints the student(s) details.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <xsl:if test = "marks > 90">
                     <tr>
                        <td><xsl:value-of select = "@rollno"/></td>
                        <td><xsl:value-of select = "firstname"/></td>
                        <td><xsl:value-of select = "lastname"/></td>
                        <td><xsl:value-of select = "nickname"/></td>
                        <td><xsl:value-of select = "marks"/></td>
                     </tr>
                  </xsl:if>
               </xsl:for-each>

            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <choose>

<xsl:choose>标签使用<xsl:otherwise>和<xsl:when>元素指定对节点内容的多个条件测试。

<xsl:choose> tag specifies a multiple conditional tests against the content of nodes in conjunction with the <xsl:otherwise> and <xsl:when> elements.

Declaration

以下是 <xsl:choose> 的语法声明。

Following is the syntax declaration of <xsl:choose> element.

<xsl:choose >
</xsl:choose>

Elements

Number of Occurrences

Unlimited

Parent elements

Child elements

xsl:otherwise, xsl:when

Demo Example

此示例通过迭代每个学生来创建带其属性 rollno 及其子属性 <firstname>、<lastname>、<nickname> 和 <marks> 的 <table> 元素。它检查并打印成绩的详细信息。

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
                  <th>Grade</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>

                     <td>
                        <xsl:choose>
                           <xsl:when test = "marks > 90">
                              High
                           </xsl:when>

                           <xsl:when test = "marks > 85">
                              Medium
                           </xsl:when>

                           <xsl:otherwise>
                              Low
                           </xsl:otherwise>
                        </xsl:choose>
                     </td>
                  </tr>
               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <key>

<xsl:key> 标记元素指定分配给 XML 文档中特定元素的已命名名称-值对。此键与 XPath 表达式中的 key() 函数一起使用，以便访问 XML 文档中的已分配元素。

<xsl:key> tag element specifies a named name-value pair assigned to a specific element in an XML document. This key is used with the key() function in XPath expressions to access the assigned elements in an XML document.

Declaration

以下是 <xsl:key> 元素的语法声明。

Following is the syntax declaration of <xsl:key> element.

<xsl:key
   name = QName
   match = Pattern
   use = Expression >
</xsl:key>

Attributes

S.No

Name & Description

Name Name of the key to be used.

Match Patterns used to identify a node that holds this key.

Use XPath expression to identify the value of the nodes of xml document.

Elements

Number of Occurrences

Unlimited

Parent elements

xsl:stylesheet

Child elements

None

Demo Example

此示例通过遍历每个学生来创建一个 <student> 元素的表格，其中包含其属性 rollno 及其子项 <firstname>、<lastname>、<nickname> 和 <marks>。它检查键作为学生的姓名之一，然后打印学生详细信息。

This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student. It checks key as firstname to be one of the student’s name and then prints the student details.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<xsl:stylesheet version = "1.0"
   xmlns:xsl = "http://www.w3.org/1999/XSL/Transform">
   <xsl:key name = "firstname-search" match = "student" use = "firstname"/>
   <xsl:template match = "/">
      <html>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "key('firstname-search', 'Dinkar')">

                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>

               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <message>

<xsl:message> 元素有助于调试XSLT处理。它类似于javascript警报。<xsl:>标签将消息缓冲到XSLT处理器中，后者将终止处理并将消息发送到调用应用程序以显示错误消息。

<message> tag element helps to debug an XSLT processing. It is similar to javascript alerts. <xsl:> tag buffers a message to XSLT processor which terminates the processing and sends a message to the caller application to display the error message.

Declaration

以下是 <xsl:message> 元素的语法声明。

Following is the syntax declaration of <xsl:message> element.

<xsl:message
   terminate = "yes" | "no" >
</xsl:message>

Attributes

Sr.No

Name & Description

terminate It specifies whether the transformation should terminate upon executing this instruction or not. Default is "yes".

Elements

Number of Occurrences

Unlimited

Parent elements

Child elements

Demo Example

此示例通过迭代每个学生创建带有其属性 rollno 及其子级<firstname>、<lastname>、<nickname>和<marks>的<student>元素的表。它检查键作为firstname是否存在，然后打印学生详细信息，否则显示错误消息。

This example creates a table of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student. It checks key as firstname to be present and then prints the student details, otherwise displays an error message.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname></firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <xsl:if test = "firstname = ''">
                     <xsl:message terminate = "yes">A first name field is empty.
                     </xsl:message>
                  </xsl:if>

                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

Output

XSLT <apply-template>

<xsl:apply-template> 标记指示 XSLT 处理器根据每个所选节点的类型和上下文查找要应用的适当模板。

<xsl:apply-template> tag signals the XSLT processor to find the appropriate template to apply, based on the type and context of each selected node.

Declaration

以下是 <xsl:apply-template> 元素的语法声明。

Following is the syntax declaration of <xsl:apply-template> element.

<xsl:apply-template
   select = Expression
   mode = QName >
</xsl:apply-template>

Attributes

Sr.No

Name & Description

select Used to process nodes selected by an XPath expression, instead of processing all the children.

mode Allows an element as specified by its Qualified Names to be processed multiple times, each time producing a different result.

Elements

Number of occurrences

Unlimited

Parent elements

Child elements

xsl:sort, xsl:with-param

Demo Example

此示例通过迭代每个 <student> 元素，以此元素的 rollno 属性及其子元素 <firstname>, <lastname>, <nickname> 和 <marks> 创建一个列表。

This example creates a list of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <xsl:apply-templates select = "class/student" />
         </body>
      </html>
   </xsl:template>

   <xsl:template match = "class/student">
      <xsl:apply-templates select = "@rollno" />
      <xsl:apply-templates select = "firstname" />
      <xsl:apply-templates select = "lastname" />
      <xsl:apply-templates select = "nickname" />
      <xsl:apply-templates select = "marks" />
      <br />
   </xsl:template>

   <xsl:template match = "@rollno">
      <span style = "font-size = 22px;">
         <xsl:value-of select = "." />
      </span>
      <br />
   </xsl:template>

   <xsl:template match = "firstname">
      First Name:<span style = "color:blue;">
         <xsl:value-of select = "." />
      </span>
      <br />
   </xsl:template>

   <xsl:template match = "lastname">
      Last Name:<span style = "color:green;">
         <xsl:value-of select = "." />
      </span>
      <br />
   </xsl:template>

   <xsl:template match = "nickname">
      Nick Name:<span style = "color:red;">
         <xsl:value-of select = "." />
      </span>
      <br />
   </xsl:template>

   <xsl:template match = "marks">
      Marks:<span style = "color:gray;">
         <xsl:value-of select = "." />
      </span>
      <br />
   </xsl:template>

</xsl:stylesheet>

Output

XSLT <import>

<xsl:import> 标记将一个样式表的內容导入另一个样式表。导入的样式表具有比被导入的样式表更高的优先级。

<xsl:import> tag imports the contents of one stylesheet into another. Importing a style sheet has higher precedence over imported stylesheet.

Declaration

以下是 <xsl:import> 元素的语法声明。

Following is the syntax declaration of <xsl:import> element.

<xsl:import href = "uri">
</xsl:import>

Attributes

Sr.No

Name & Description

href used to pass the path of xslt stylesheet to be imported .

Elements

Number of occurrences

Unlimited

Parent elements

xsl:stylesheet, xsl:transform

Child elements

none

Demo Example

此示例通过迭代每个学生来创建带其属性 rollno 及其子属性 <firstname>、<lastname>、<nickname> 和 <marks> 的 <student> 元素列表。此处，我们创建了两个 xsl 样式表，其中 students_imports.xsl 样式表导入 students.xsl，students.xml 链接至 students_imports.xsl。

This example creates a list of <student> element with its attribute rollno and its child <firstname>, <lastname>, <nickname>, and <marks> by iterating over each student. Here we have created two xsl stylesheets where students_imports.xsl stylesheet imports students.xsl and students.xml is linked to students_imports.xsl.

students.xml

<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "students_imports.xsl"?>
<class>
   <student rollno = "393">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno = "493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>Vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno = "593">
      <firstname>Jasvir</firstname>
      <lastname>Singh</lastname>
      <nickname>Jazz</nickname>
      <marks>90</marks>
   </student>
</class>

students.xsl

<?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>
         <body>
            <h2>Students</h2>
            <table border = "1">
               <tr bgcolor = "#9acd32">
                  <th>Roll No</th>
                  <th>First Name</th>
                  <th>Last Name</th>
                  <th>Nick Name</th>
                  <th>Marks</th>
               </tr>

               <xsl:for-each select = "class/student">

                  <tr>
                     <td><xsl:value-of select = "@rollno"/></td>
                     <td><xsl:value-of select = "firstname"/></td>
                     <td><xsl:value-of select = "lastname"/></td>
                     <td><xsl:value-of select = "nickname"/></td>
                     <td><xsl:value-of select = "marks"/></td>
                  </tr>
               </xsl:for-each>
            </table>
         </body>
      </html>
   </xsl:template>
</xsl:stylesheet>

students_imports.xsl

<?xml version = "1.0" encoding = "UTF-8"?>
<xsl:stylesheet version = "1.0"
   xmlns:xsl = "http://www.w3.org/1999/XSL/Transform">
   <xsl:import href = "students.xsl"/>
   <xsl:template match = "/">
      <xsl:apply-imports/>
   </xsl:template>
</xsl:stylesheet>