EL_获取域中存储的值
- el表达式只能从域对象中获取值
- 语法
-
- ${域名称.键名}：从指定域中获取指定键的值
- 域名称：
- pageScope -->pageContext
- requestScope -->request
- sessionScope -->session
- applicationScope -->application（ServletContext）
- 域名称：
- 举例：在request域中存储了name=张三
- 获取：${requestScope.name}
- ${域名称.键名}：从指定域中获取指定键的值
- ${键名}：表示依次从最小的域中查找是否有该对于的值 直到找到为之
jsp代码
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>el获取域中的数据</title>
</head>
<body>
<%
//在域中存储数据
request.setAttribute("name","张三");
session.setAttribute("age","23");
%>
<h3>el获取值</h3>
${requestScope.name}
${sessionScope.age}
${sessionScope.haha}
</body>
</html>
运行结果
获取域中存储对象值
获取对象、List集合、Map集合的值
- 对象：${域名称.键名.属性名}
- 本质上会去调用对象的getter方法
实体类
package com.bai.dao;
import java.text.SimpleDateFormat;
import java.util.Date;
public class User {
private String name;
private int age;
private Date birthday;
public User(String name, int age, Date birthday) {
this.name = name;
this.age = age;
this.birthday = birthday;
}
public User() {
}
public String getBirStr(){
if (birthday !=null){
//格式化日期对象
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//返回字符串即可
return sdf.format(birthday);
}else{
return "";
}
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
}
jsp代码
<%@ page import="com.bai.dao.User" %>
<%@ page import="java.util.Date" %><%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2022/8/16
Time: 16:39
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>el获取对象值</title>
</head>
<body>
<%
User user = new User();
user.setName("张三");
user.setAge(23);
user.setBirthday(new Date());
request.setAttribute("u",user);
%>
<h3>el获取对象中的值</h3>
${requestScope.u}<br>
<%--
<%
通关的是对象的属性来获取
setter或getter方法 去掉set或get 在将剩余部分 首部分变为小写
setName-->Name-->name
%>
--%>
${requestScope.u.name}<br>
${u.age}<br>
${u.birthday}<br>
${u.birthday.month}<br>
${u.birStr}<br>
</body>
</html>
运行结果
