JSP JSTL <x:when> 标签 - JSP 基础教程 - 简单教程，简单编程

JSP 标准标签库(JSTL) <x:when> 相当于 Java when 语句中的 case 语句

switch 语句有 case 语句，而 <x:choose> 标签有 <x:when>标签
switch 语句有 default 语句，而 <x:choose>标签有 <x:otherwise> 标签

语法格式

<x:choose>
 <x:when select="<string>">
     ...
 </x:when>
 <x:when select="<string>">
     ...
 </x:when>
     ...
     ...
 <x:otherwise>
     ...
 </x:otherwise>
</x:choose>

属性

属性	描述	是否必要	默认值
select	条件	是	无

范例

webapp/jstl_xml_when.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml" %>
<!DOCTYPE html>
<meta charset="utf-8">
<title>JSTL x:when 标签 - JSP 基础教程 | 简单教程(www.twle.cn)</title>
<h3>Books Info:</h3>
<c:set var="xmltext">
  <books>
    <book>
      <name>Padam History</name>
      <author>ZARA</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 = 'ZARA'">
      Book is written by ZARA
   </x:when>
   <x:when select="$output//book/author = 'NUHA'">
      Book is written by NUHA
   </x:when>
   <x:otherwise>
      Unknown author.
   </x:otherwise>
</x:choose>
<p>JSTL x:when 标签 - JSP 基础教程 | 简单教程(www.twle.cn)</p>

在浏览器上输入 http://localhost:8080/jsp/jstl_xml_when.jsp 显示如下