EL-JSTL
JAVAWEB开发包的下载百度云链接：https://pan.baidu.com/s/15mkgNcEBXsZ-D30s9RKL8A
EL相关代码操作：
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
pageContext.setAttribute("msg","pageContext");
session.setAttribute("msg","session");
request.setAttribute("msg","request");
application.setAttribute("msg","application");
%>
pageContext:${pageScope.msg}<br/>
session:${sessionScope.msg}<br/>
request:${requestScope.msg}<br/>
application:${applicationScope.msg}<br/>
<%
List list=new ArrayList();
request.setAttribute("list",list); //必须放到作用域里面获取
%>
获取上下文路径
${empty list}
${pageContext.request.contextPath}
${pageContext.getRequest().getContextPath()}
</body>
</html>
jstl相关标签库查找大全：参考手册链接：https://pan.baidu.com/s/17UT9G0hNL6ooFLK3V--zVA
相关代码操作：
<%@page import="java.util.Arrays"%>
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
Integer age=18;
request.setAttribute("age", age);
%>
<c:if test="${age>18 }" var="ret" scope="page"></c:if>
判断的结果为 ${ret}
<hr/>
<c:choose>
<c:when test="${age>60 }">
您太老了，我怕你承受不住
</c:when>
<c:when test="${age<18 }">
您太嫩了，我不想让你受到伤害
</c:when>
<c:otherwise>
你们刚好，接我一招
</c:otherwise>
</c:choose>
<hr/>
<%
List<String> stu=Arrays.asList(new String[]{"zhouzhou","xinxin","chichi"});
request.setAttribute("stu", stu);
%>
<c:forEach items="${stu}" var="item" varStatus="vs">
${vs.count}----->${pageScope.item}<br>
</c:forEach>
<c:forEach var="num" begin="1" end="10" step="1">
${pageScope.num}<br>
</c:forEach>
</body>
</html>
<%@page import="java.util.Date"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<fmt:setBundle basename="app"/>
<form action="">
<fmt:message key="username"/><input type="text" name="username" /><br>
<fmt:message key="password"/><input type="password" name="password" /><br>
<input type="submit" name="username" />
</form>
<hr/>
<%
Date date=new Date();
request.setAttribute("date", date);
%>
当地时间：<fmt:formatDate value="${ date}" pattern="yyyy-MM-dd HH:mm:ss SS"/>
</body>
</html>