EL优化登录界面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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 'login.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>
<form action="loginServlet" method="post">
姓名:<input type="text" name="username"><br>
密码:<input type="password" name="userpassword">
<button>登录</button>
<span style="color: red;font-size:12px">${msg}</span>
</form>
</body>
</html>将<span style="color: red;font-size:12px"><%=request.getAttribute("msg") %></span>
改成<span style="color: red;font-size:12px">${msg}</span>
节省了代码量也提高了效率
效果如下：
在msg为NULL的时候，msg并不会显示。
EL获取对象
EL操作不了局部变量。
EL在操作域对象的时候一般是从小到大依次访问。
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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 'EL.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>
<%
//设置page属性
pageContext.setAttribute("name","zhangsan");
//设置request属性
request.setAttribute("name","lisi");
//设置session属性
session.setAttribute("name","wangwu");
//设置appication属性
application.setAttribute("name","zhaoliu");
String str = "Hello ";
%>
//获取局部变量
${str}<br>
//获取域对象
${name}<br>
</body>
</html>
