<x:if> Tag

JSP 标准标签库JSP Standard Tag Library

The <x:if> tag is used to evaluate an XPath expression; if it is true, the content of its body is executed; if it is false, the content of its body is ignored.

Syntax Format

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

Attributes

The <x:if> tag has the following attributes:

Attribute Description Required Default Value
select The XPath expression to be evaluated Yes None
var The variable to store the result of the condition no None
scope The scope of the var attribute no Page

Example Demonstration

The following example shows us how to use the <x:if> tag:

<%@ 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>

The output is as follows:


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

JSP 标准标签库JSP Standard Tag Library

Other Extensions