//EL表达式的原理

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<html>
 <head>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">



 </head>

 <body>
<%
String s="hello";
pageContext.setAttribute("s",s);
%>
<jsp:useBean id="s1" class="com.itheima.domain.Student" scope="session"></jsp:useBean>

 ${s } 
 <%
// pageContext.setAttribute("k","kkkko");
 request.setAttribute("k","aaarrkkrr");
 %>
 ${k }
 ${s1 }
 <%--
//EL表达式的原理
String str=(String)pageContext.findAttribute("p");//依次从 page request session application中查找
if(str==null)
 out.write("");
else
 out.write(str);
 --%>

 ${uhfufu.name } 
 ${s1.address.province } 
 ${s1["address"]["province"] } 
 ${s1.class.simpleName } 
 ${s1.class.name } 
 ${s1.class }
 <%
 List list=new ArrayList();
 list.add("a");
 list.add("b");
 list.add("c");
 list.add("d");
 pageContext.setAttribute("list",list);
 %>
 ${list[3] } 
 <%
 Map map=new HashMap();
 map.put("a","aa");
 map.put("c","cc");
 map.put("b","bb");
 pageContext.setAttribute("map",map);
 %>
 ${map .b}
 </body>
</html>

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//EL表达式的原理

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