<x:if> 标签

JSP 标准标签库

<x:if>标签用于判断一个XPath表达式的值，若为真，则执行其主体中的内容，若为假则其主体的内容将会被忽略。

语法格式

<x:if
  select="<string>"
  var="<string>"
  scope="<string>">   
   ...
</x:if>

属性

<x:if>标签有如下属性：

实例演示

接下来的例子告诉我们如何使用<x:if>标签：

<%@ 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:if 标签</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:if select="$output//book">
   Document has at least one <book> element.
</x:if>
<br />
<x:if select="$output/books[1]/book/price > 100">
   Book prices are very high
</x:if>

</body>
</html>

运行结果如下：

BOOKS INFO:
Document has at least one <book> element. 
Book prices are very high

JSP 标准标签库