<x:if >
《x:if》标记评估test XPath expression ,如果为true,则处理其正文。 如果测试条件为假,则忽略正文。
属性 (Attribute)
《x:if》标记具有以下属性 -
属性 | 描述 | 需要 | 默认 |
---|---|---|---|
select | 要评估的XPath表达式 | Yes | None |
var | 用于存储条件结果的变量的名称 | No | None |
scope | var属性中指定的变量的范围 | No | Page |
例子 (Example)
以下示例显示了使用《x:if》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:if Tags</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>
现在让我们访问上面的JSP,将显示以下结果 -
<h3>Books Info:</h3>
Document has at least one <book> element.
Book prices are very high