EL
index.jsp
<%@page import="com.bean.Student"%>
<%@ 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 '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>
<%
pageContext.setAttribute("username", "page的名字");
request.setAttribute("username", "request的名字");
session.setAttribute("username", "session的名字");
application.setAttribute("username", "application的名字");
Student s = new Student();
s.setName("二喜");
request.setAttribute("student", s);
List<String> list = new ArrayList<String>();
list.add("三喜");
list.add("喜欢");
list.add("学习");
request.setAttribute("list", list);
Map<String,Object> map = new HashMap();
map.put("username", "四喜");
map.put("userpwd", "1234");
request.setAttribute("map", map);
%>
<!--El表达式取值 (在不指定默认值时会从最小的作用域中取值) -->
${username}<br>
${pageScope.username}<br>
${requestScope.username}<br>
${sessionScope.username}<br>
${applicationScope.username}<br>
<!-- EL在对象中取值的两种方式 -->
姓名：${student.name}
${student["name"]} <br>
<!-- 集合取值可以通过数组取值 -->
集合取值：${list}
${list[0]}${list[1]}${list[2]} <br>
<!-- map取值的两种方法 -->
map的值：${map.username} ${map.userpwd} <br>
${map["username"]} ${map["userpwd"] }
<br><br>
====算术运算符====
${1+1}<br>
<!-- 页面报错不会直接抛异常 -->
${1/0}<br>
====关系运算符(结果ture或者false)====
${1>2}<br>
====逻辑运算符(结果ture或者false)====
${1>2||1<2}<br>
====空值判断 empty运算符(结果ture或者false)====
${empty username}<br>
<a href = "a.jsp?a=erxi">param传值</a>
</body>
</html>
JSTL
a.jsp
<%@ 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 'a.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="b.jsp" method = "post">
昵称：<input name = "name"><br>
所在城市：<input name = "city"><br>
您所使用的开发语言：<input name = "language" type = "checkbox" value = "java">java
<input name = "language" type = "checkbox" value = "C">C
<input name = "language" type = "checkbox" value = "C++">C++
<input name = "language" type = "checkbox" value = "PHP">PHP
<input name = "language" type = "checkbox" value = "ASP">ASP
<br>
<input type = "submit" value = "提交">
</form>
//param取值
${param.a}
<%=request.getParameter("a") %>
(两种方法效果相同)
</body>
</html>
b.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'b.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String name = request.getParameter("name");
String city = request.getParameter("city");
String[] languages = request.getParameterValues("language");
List list = new ArrayList();
for(String language:languages){
list.add(language);
}
request.setAttribute("name", name);
request.setAttribute("city", city);
request.setAttribute("list", list);
%>
昵称：${name}
城市：${city}
您所使用的开发语言：${list[0]}${list[1]}${list[2]}${list[3]}${list[4]}
</body>
</html>
c.jsp
<%@page import="com.bean.Student"%>
<%@ 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 'c.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>
<%
Student s = new Student();
request.setAttribute("s",s);
%>
<body>
通用标签-set设置指定范围内的变量值
<c:set var= "name" value = "二喜" scope="request"></c:set>
request:${requestScope.name}<br>
session:${sessionScope.name}
<c:set target="${s}" property = "name" value = "三喜"></c:set>
${s.name}<br>
通用标签-out：计算表达式并将结果输出显示
<c:out value="${s.name }"></c:out><br>
通用标签-remove删除指定范围内的变量
<c:remove var="name"/>
${name}<br>
条件标签-if实现Java语言中if语句的功能
<c:if test="${1<2}">
1《2是对的
</c:if><br>
</body>
</html>