EL运算符：
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.sql.*" %>
!DOCTYPE html>
html>
head>
title>El算数运算符/title>
/head>
body>
table border=1>
tr>
td>算数运算符/td>
td>结果/td>
/tr>
tr>
td>加法运算符\${1 + 1}/td>
td>结果${1+1}/td>
/tr>
tr>
td>减法运算符\${1 - 1}/td>
td>结果${1-1}/td>
/tr>
tr>
td>乘法运算符\${1 * 2}/td>
td>结果${1 * 1}/td>
/tr>
tr>
td>除法运算符\${3 / 2}/td>
td>结果${3 / 2}/td>
/tr>
tr>
td>求余运算符\${3 % 2}/td>
td>结果${3 % 2}/td>
/tr>
/table>
table border=1>
tr>
td>关系运算符/td>
td>结果/td>
/tr>
tr>
td>等于运算符\${1 == 1}/td>
td>结果${1==1}/td>
/tr>
tr>
td>不等于运算符\${1 != 1}/td>
td>结果${1!=1}/td>
/tr>
tr>
td>小于运算符\${1 lt; 2}/td>
td>结果${1 2}/td>
/tr>
tr>
td>大于运算符\${3 gt; 2}/td>
td>结果${3 > 2}/td>
/tr>
tr>
td>小于等于运算符\${1 lt;= 2}/td>
td>结果${1 = 2}/td>
/tr>
tr>
td>大于等于运算符\${3 gt;= 2}/td>
td>结果${3 >= 2}/td>
/tr>
/table>
table border=1>
tr>
td>逻辑运算符/td>
td>结果/td>
/tr>
tr>
td colspan="2">逻辑运算符/td>
/tr>
tr>
td>\${true true}/td>
td>结果${true true}/td>
/tr>
tr>
td>\${true false}/td>
td>结果${true false}/td>
/tr>
tr>
td>\${false false}/td>
td>结果${false false}/td>
/tr>
tr>
td colspan="2">逻辑运算符||/td>
/tr>
tr>
td>\${true || true}/td>
td>结果${true || true}/td>
/tr>tr>
td>\${true || false}/td>
td>结果${true || false}/td>
/tr>tr>
td>\${false || false}/td>
td>结果${false || false}/td>
/tr>
tr>
td colspan="2">逻辑运算符!/td>
/tr>
tr>
td>\${!true}/td>
td>结果${!true}/td>
/tr>tr>
td>\${!false}/td>
td>结果${!false}/td>
/tr>
/table>
table border=1>
tr>
td>条件运算符/td>
td>结果/td>
/tr>
tr>
td>\${2>1?"Yes":"No"}/td>
td>结果${2>1?"Yes":"No"}/td>
/tr>
tr>
td>\${21?"Yes":"No"}/td>
td>结果${21?"Yes":"No"}/td>
/tr>
/table>
table border=1>
tr>
td>验证运算符/td>
td>结果/td>
/tr>
tr>
td>\${empty param.username}/td>
td>结果${empty param.username}/td>
/tr>
tr>
td>\${empty param.password}/td>
td>结果${empty param.password}/td>
/tr>
/table>
table border=1>
tr>
td>括号运算符及运算符的优先级/td>
td>结果/td>
/tr>
/table>
/body>
/html>
EL处理内置对象：
“.”和"[]"符号是用来存取数据的
${applicationScope.user.username}
${applicationScope.user[0].username}
${applicationScope.user["user-name"]}
通过变量来传值就必须使用[]
${applicationScope.user["data"]}
与存储有关的内置对象
!DOCTYPE html>
html>
head>
title>与存储有关的内置对象/title>
/head>
body>
%
//application范围设置属性name，值为application_name
application.setAttribute("name","application_name");
//session范围设置属性name，值为session_name
session.setAttribute("name","session_name");
//request范围设置属性name，值为request_name
request.setAttribute("name","request_name");
//page范围设置属性name，值为page_name
pageContext.setAttribute("name","page_name");
%>
%--获取page范围内的name属性--%>
page范围内的那么属性的值为：${pageScope.name}br />
%--获取request范围内的name的属性--%>
request范围内的那么属性的值为：${requestScope.name}br />
%--获取session范围内的name的属性--%>
session范围内的那么属性的值为：${sessionScope.name}br />
%--获取application范围内的name属性--%>
application范围内的那么属性的值为：${applicationScope.name}br />
/body>
/html>
与输入有关的内置对象
!DOCTYPE html>
html>
head>
title>用户表单/title>
/head>
body>
form action="UserDemo.jsp" method="post">
用户名：input type="text" name="username" />br />
密码：input type="password" name="password" />br />
姓名：input type="text" name="name" />br />
性别：input type="radio" name="sex" value="男">男input type="radio" name="sex" value="女">女br />
爱好：br />
input type="checkbox" name="interest" value="打篮球">打篮球br />
input type="checkbox" name="interest" value="看书">看书br />
input type="checkbox" name="interest" value="旅行">旅行br />
input type="checkbox" name="interest" value="编程">编程br />
input type="submit" value="提交">
input type="reset" value="重置">
/form>
/body>
/html>
!DOCTYPE html>
html>
head>
title>接收用户参数/title>
/head>
body>
%
//设置页面编码格式
request.setCharacterEncoding("gb2312");
%>
%--接收用户参数--%>
用户名：${span style="color:#003399;">param/span>.username}br />
密码：${span style="color:#003399;">param/span>.password}br />
姓名：${span style="color:#003399;">param/span>.name}br />
性别：${span style="color:#003399;">param/span>.sex}br />
爱好：${span style="color:#003399;">paramValues/span>.interest[0]}
${span style="color:#003399;">paramValues/span>.interest[1]}
/body>
/html>
cookie内置对象
!DOCTYPE html>
html>
head>
title>设置cookie的值/title>
/head>
body>
%
//设置cookie的值
Cookie c = new Cookie("username","root");
//添加cookie到客户端
response.addCookie(c);
%>
a href="getCookieDemo.jsp">显示cookie的值/a>
/body>
/html>
span style="color:#000000;">%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>取得cookie的值/title>
/head>
body>
cookie中的username的值为：${cookie.username.value}
/body>
/html>
header内置对象
!DOCTYPE html>
html>
head>
title>取得header的值/title>
/head>
body>
${header["host"]}br />
${header["user-agent"]}br />
/body>
/html>
initParam内置对象:获取web站点中设置的环境变量
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>获得环境参数/title>
/head>
body>
username参数值：${initParam.username}br />
/body>
/html>
?xml version="1.0" encoding="ISO-8859-1"?>
web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
context-param>
param-name>username/param-name>
param-value>Zhangdapeng/param-value>
/context-param>
/web-app>
pageContex内置对象
用来取得有关用户请求和页面的详细信息
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>pageContext演示/title>
/head>
body>
table border="1">
tr>
td>取得请求的参数的字符串/td>
td>${pageContext.request.queryString}/td>
/tr>tr>
td>取得请求URL/td>
td>${pageContext.request.requestURL}/td>
/tr>tr>
td>取得web应用名称/td>
td>${pageContext.request.contextPath}/td>
/tr>tr>
td>取得HTTP请求方式（POST/GET）/td>
td>${pageContext.request.method}/td>
/tr>tr>
td>取得使用的协议/td>
td>${pageContext.request.protocol}/td>
/tr>tr>
td>取得用户IP地址/td>
td>${pageContext.request.remoteAddr}/td>
/tr>tr>
td>判断session是否为新/td>
td>${pageContext.session.new}/td>
/tr>tr>
td>取得session的id/td>
td>${pageContext.session.id}/td>
/tr>
/table>
/body>
/html>
EL存取器:
使用存取器读取JavaBean中的数据
package com.javaweb.ch08;
import java.util.*;
//一个简单的JavaBean示例
public class Person{
//name属性
private String name;
//age属性
private int age;
//sex属性
private String sex;
//friends属性
private ArrayList friends;
//无参构造方法
public Person(){
}
//自定义构造的方法
public Person(String name,int age,String sex){
this.name = name;
this.age = age;
this.sex = sex;
}
//获取name的属性值
public String getName(){
return name;
}
//获取age属性值
public int getAge(){
return age;
}
//获取sex的属性值
public String getSex(){
return sex;
}
//设置name的属性
public void setName(String name){
this.name = name;
}
//设置age的属性值
public void setAge(int age){
this.age = age;
}
//设置sex的属性值
public void setSex(String sex){
this.sex = sex;
}
//设置friends的值
public void setFriends(ArrayList friends){
this.friends = friends;
}
//获取friends的属性值
public ArrayList getFriends(){
return friends;
}
}
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.util.*,com.javaweb.ch08.*" %>
!DOCTYPE html>
html>
head>
title>设置JavaBean中的属性/title>
/head>
body>
%
//实例化一个Person
Person person = new Person("zhangdapeng",24,"男");
//创建一个friends实例
ArrayList friends = new ArrayList();
//添加值
friends.add("wang wu");
friends.add("li si");
person.setFriends(friends);
//存储在session范围内
session.setAttribute("person",person);
%>
a href="GetJavaBean.jsp">跳转到GetJavaBean.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>取得JavaBean中的属性值/title>
/head>
body>
姓名：${sessionScope.person.name}br />
年龄：${sessionScope.person.age}br />
性别：${sessionScope.person.sex}br />
朋友：${sessionScope.person.friends[0]},${sessionScope.person.friends[1]}br />
/body>
/html>
使用存储器读取Map中的数据
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.util.*,com.javaweb.ch08.*" %>
!DOCTYPE html>
html>
head>
title>设置Map页面/title>
/head>
body>
%
//新建一个HashMap
HashMap userInfo = new HashMap();
//在HashMap中设置值
userInfo.put("username","zhangdapeng");
userInfo.put("password","zhnagda123");
//将值存储到session范围中
session.setAttribute("userInfo",userInfo);
%>
a href="GetMapDemo.jsp">跳转到GetMapDemo.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>使用存储器读取map中的数据/title>
/head>
body>
用户名：${sessionScope.userInfo.username}br />
密码：${sessionScope.userInfo.password}br />
/body>
/html>
使用存储器读取数组中的数据
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.util.*,com.javaweb.ch08.*" %>
!DOCTYPE html>
html>
head>
title>设置Array页面/title>
/head>
body>
%
String[] names = {"zhangda1","zhangda2","zhangda3"};
//将值存储到session范围中
session.setAttribute("names",names);
%>
a href="GetMapDemo.jsp">跳转到GetArrayDemo.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>使用存储器读取map中的数据/title>
/head>
body>
用户名1：${sessionScope.names[0]}br />
用户名2：${sessionScope.names[1]}br />
/body>
/html>
存储器的复杂应用
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.util.*,com.javaweb.ch08.*" %>
!DOCTYPE html>
html>
head>
title>设置Array页面/title>
/head>
body>
%
ArrayListPerson> persons = new ArrayListPerson>();
Person person1 = new Person("wang wu",24,"男");
Person person2 = new Person("wang liu",24,"女");
persons.add(person1);
persons.add(person2);
session.setAttribute("persons",persons);
%>
a href="GetMapDemo.jsp">跳转到GetArrayDemo.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>使用存储器读取map中的数据/title>
/head>
body>
用户名1：${sessionScope.persons[0].name},${sessionScope.persons[0].age},${sessionScope.persons[0].sex}br />
用户名2：${sessionScope.persons[1].name},${sessionScope.persons[1].age},${sessionScope.persons[1].sex}br />
/body>
/html>
