初识EL
EL作用:简化JSP页面书写
EL格式:以”${“开始，以”}”结束
具体格式：

${表达式}
代码举例
<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2021/4/6
  Time: 14:45
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
    pageContext.setAttribute("book1","JavaWeb");
    pageContext.getRequest().setAttribute("book1","活着");
    pageContext.getSession().setAttribute("book1","盗墓笔记");
    pageContext.getServletContext().setAttribute("book1","我们仨");
%>
${pageScope.book1}<br>
<hr />
${requestScope.book1}<br>
<hr />
${sessionScope.book1}<br>
<hr />
${applicationScope.book1}<br>
</body>
</html>

使用EL获取不同域中的值

注意：如果不指明范围，全域查找，从小到大，找到即返回${book1}

NOTE:下一页项目示例