2.获取值
1. el表达式只能从域对象中获取值
2. 语法：
1. ${域名称.键名}：从指定域中获取指定键的值
域名称：
1. pageScope --> pageContext
2. requestScope --> request
3. sessionScope --> session
4. applicationScope --> application（ServletContext）
举例：在request域中存储了name=张三
获取：${requestScope.name}
2. ${键名}：表示依次从最小的域中查找是否有该键对应的值，直到找到为止。
3. 获取对象、List集合、Map集合的值
1. 对象：${域名称.键名.属性名}
本质上会去调用对象的getter方法
<%@ 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
session.setAttribute("name","李四");
request.setAttribute("name","张三");
session.setAttribute("age","23");
request.setAttribute("str","");
%>
<h3>el获取值</h3>
${requestScope.name}
${sessionScope.age}
${sessionScope.haha}
${name}
${sessionScope.name}
</body>
</html>
<%@ page import="java.util.*" %>
<%@ page import="com.example.domain.User" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>el获取数据</title>
</head>
<body>
<%
User user = new User();
user.setName("张三");
user.setAge(23);
user.setBirthday(new Date());
request.setAttribute("u",user);
List list = new ArrayList();
list.add("aaa");
list.add("bbb");
list.add(user);
request.setAttribute("list",list);
Map map = new HashMap();
map.put("sname","李四");
map.put("gender","男");
map.put("user",user);
request.setAttribute("map",map);
%>
<h3>el获取对象中的值</h3>
${requestScope.u}<br>
<%--
* 通过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，首字母变为小写。
* setName --> Name --> name
--%>
${requestScope.u.name}<br>
${u.age}<br>
${u.birthday}<br>
${u.birthday.month}<br>
${u.birStr}<br>
<h3>el获取List值</h3>
${list}<br>
${list[0]}<br>
${list[1]}<br>
${list[10]}<br>
${list[2].name}
<h3>el获取Map值</h3>
${map.gender}<br>
${map["gender"]}<br>
${map.user.name}
</body>
</html>
----------
package com.example.domain;
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() {
}
/**
* 逻辑视图
* @return
*/
public String getBirStr(){
if(birthday != null){
//1.格式化日期对象
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//2.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;
}
}
标签：EL,存储,name,el,age,获取,birthday,public From： https://www.cnblogs.com/agzq/p/17113418.html