<x:choose>, <x:when>, <x:otherwise> 標籤

JSP 標準標籤庫JSP 標準標籤庫

<x:choose>標籤與Java switch語句有相同的功能。switch語句有case語句，而<x:choose>標籤有<x:when>標籤。switch語句有default語句，而<x:choose>標籤有<x:otherwise>標籤。

語法格式

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

屬性

  • <x:choose>沒有屬性。
  • <x:when>的屬性在下表中給出。
  • <x:otherwise>沒有屬性。

<x:when>標籤的屬性：

屬性 描述 是否必要 默認值
select 條件 是 無
 

實例演示

<%@ 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" %>

<html>
<head>
  <title>JSTL x:choose 標籤</title>
</head>
<body>
<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>

</body>
</html>

運行結果如下：

BOOKS INFO:
Book is written by ZARA

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