EL表达式学习笔记(JSTL)

最新推荐文章于 2025-09-05 16:34:31 发布

weixin_30663391

最新推荐文章于 2025-09-05 16:34:31 发布

阅读量61

点赞数

CC 4.0 BY-SA版权

文章标签： java

原文链接：http://www.cnblogs.com/hbiao68/archive/2011/10/19/2218244.html

本文深入解析JSP页面中EL表达式的用法，包括基本语法、运算符、空值判断及与对象方法的关联，通过实例展示如何灵活运用EL表达式进行变量引用和条件判断。

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>

<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'JSTL_test.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
    <h1>测试EL表达式</h1>
	<hr>
	<li>普通字符串</li>
	hello(jsp脚本):<%request.getAttribute("hello");%><br>
	hello(EL表达式使用$和{}):${hello}<br>
	hello(el表达式,el的隐含对象：pageScope,requestScope,sessionScope,applicationScope<br>如果没有指定scope，则它的搜索顺序为
	pageScope ----> applicationScope):${requestScope.hello }<br>
	
	<li>结构</li>
	姓名：${user.userName}(与对象的方法(get)相关)<br>
	年龄：${user.age }<br>
	所属组：${user.group.name }<br>
	
	<li>输出map</li>
	mapvalue.key1:${mapvalue.key1 }<br>
	mapvalue.key2:${mapvalue.key2 }<br>
	
	<li>数组输出，采用[]和下标</li>
	atrarray[2]:${astarray[1] }<br>
	
	<li>输出对象数组</li>
	userarray[3].username:${users[2].username }<br>
	
	<li>输出list,采用[]和下标</li>
	userlist[5].username:${userlist[4].username }<br>
	
	<li>el表达式对运算符的支持</li>
	1 + 2 = ${1+2 }<br>
	10 / 5 = ${10/5 }<br>
	10 / 5 = ${10 div 5 }<br>
	10 % 3 = ${10%3 }<br>
	10 % 3 = ${10 mod 3 }<br>
	<--
		==    eq
		!=    ne
		<     lt
		>     gt
		<=    le
		>=    ge
		&&    and
		||    or
		!     not
		/     div
		%     mod
	-->
	
	<li>测试empty</li>
	value1:${not empty value1 }<br>
	value2:${empty value1 }<br>
	value3:${empty value1 }<br>
	value4:${empty value1 }<br>
	
  </body>
</html>

转载于:https://www.cnblogs.com/hbiao68/archive/2011/10/19/2218244.html