JSP的EL表达式和JSTL标准标签库

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红酒人生 2021-08-16 22:19:00

文章标签 java 作用域 html css 二维码 文章分类 Html/CSS 前端开发

理论如下：

JSP的EL表达式和JSTL标准标签库_html

二.代码示例如下：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
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 'index.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>
在request作用域对象设值： <c:set var="username" value="holly" scope="request"/>
<br/>
输出request作用域对象值：<c:out value="${requestScope.username}"/>
<br/>
<%--
删除作用域对象：<c:remove var="username" scope="request"/>
<br/>
输出request作用域对象值：<c:out value="${requestScope.username}"/>
<br/>
--%>
<c:if test="${not empty requestScope.username}">
<c:choose>
<c:when test="${requestScope.username eq 'holly'}">
用户名为：<c:out value="${requestScope.username}"/>
</c:when>
<c:otherwise>
<c:out value="登录错误！"/>
</c:otherwise>
</c:choose>
</c:if>
</body>
</html>