JSP jstl-<x:when> 标记

  • jstl-<x:when> 标记

    <x:choose>标签的运作方式类似于Java的switch语句。有了这个,您可以在多种选择之间进行选择。如果switch语句具有case语句,则<x:choose>标记具有<x:when>标记。以类似的方式,switch语句具有default子句以指定默认操作,而≪x:choose>标记具有≪x:otherwise>标记作为默认子句。
  • 属性

    属性 描述 必需 默认值
    select 要评估的XPath表达式 没有
  • 示例

    以下示例将显示如何使用<x:when>标记-
    
    <%@ taglib prefix = "c" uri = "http://java.sun.com/jsp/jstl/core" %>
    <%@ taglib prefix = "x" uri = "http://java.sun.com/jsp/jstl/xml" %>
    
    <html>
       <head>
          <title>JSTL x:choose Tags</title>
       </head>
    
       <body>
          <h3>Books Info:</h3>
          
          <c:set var = "xmltext">
             <books>
                <book>
                   <name>Padam History</name>
                   <author>MOO</author>
                   <price>100</price>
                </book>
                
                <book>
                   <name>Great Mistry</name>
                   <author>NUHA</author>
                   <price>2000</price>
                </book>
             </books>
          </c:set>
    
          <x:parse xml = "${xmltext}" var = "output"/>
          <x:choose>
             <x:when select = "$output//book/author = 'MOO'">
                Book is written by MOO
             </x:when>
             
             <x:when select = "$output//book/author = 'NUHA'">
                Book is written by NUHA
             </x:when>
             
             <x:otherwise>
                Unknown author.
             </x:otherwise>
          </x:choose>
    
       </body>
    </html>
    
    上面的代码将产生以下结果-
    
    Books Info:
    
    Book is written by MOO