JSP EL表达式
最编程
2024-08-12 15:46:15
...
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%-- EL表达式 默认值空 不是null
操作域对象中的数据 不能局部变量
从小到大去找--%>
<%
//设置数据
pageContext.setAttribute("name1","pageC");
request.setAttribute("name2","req");
session.setAttribute("name3","sess");
application.setAttribute("name4","app");
%>
<%-- 获取数据--%>
${"name"}
<%-- 获取指定范围--%>
${pageScope.name1}
${requestScope.name2}
${sessionScope.name3}
${applicationScope.name4}
</body>
</html>
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.Map" %>
<%@ page import="java.util.HashMap" %>
<%@ page import="bean.User" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%
List<String> list=new ArrayList<>();
list.add("aaa");
list.add("bbb");
request.setAttribute("list",list);
Map map=new HashMap();
map.put("bbb",111);
request.setAttribute("map",map);
//JavaBean 必须提供get方法
User user=new User("String");
request.setAttribute("user",user);
%>
<%-- 获取集合值--%>
${list.size()}<br>
${list[1]}<br>
${map.bbb}<br>
${map[bbb]}<br>
<%--javabean--%>
${user}<br>
${user.name}<br>
${user.getName()}
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%
request.setAttribute("str1","");
request.setAttribute("str2","str2");
request.setAttribute("str3",null);
%>
<%-- empty 判断域对象是否为空
有值为false
空 null都为true
--%>
${empty str1}<br>
${empty str3}<br>
${empty str2}<br>
${empty str4}<br>
</body>
</html>
原文地址:https://www.cnblogs.com/lwx11111/p/16175214.html
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