<x:if>标记计算测试XPath表达式,如果为ture,它处理它的主体(body)。如果测试条件为false,主体(body)被忽略。
<x:if>标签具有以下属性:
属性 | 描述 | 必须 | 默认 |
---|---|---|---|
select | XPath表达式被计算 | Yes | None |
var | 变量名称来存储条件的结果 | No | None |
scope | 在var属性指定的变量范围 | No | Page |
下面是一个例子,说明<x:if>标记的用法:
<%@ 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>
现在让我们尝试访问上面的JSP,这将产生以下结果:
BOOKS INFO:Document has at least one <book> element.Book prices are very high |