SessionAttributes注解只能放到类上面，不能放在方法上面。
SessionAttributes注解除了可以通过属性名指定需要放到会话中的属性外（value属性值），还可以通过模型属性的对象类型指定哪些模型属性需要放到会话中（types属性值）。
testSessionAttributes类
@SessionAttributes(value={"user"},types={String.class})
@Controller
public class Hello{
@RequestMapping("/testSessionAttributes")
public String testSessionAttributes(Map<String, Object> map){
User user = new User("Tom", "123456789", "[email protected]", 16);
map.put("user", user);
map.put("school", "WBU");
return "success";
}
}success.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>Success page</h1>
request user:${requestScope.user }
<br><br>
sessiong user:${sessionScope.user }
<br><br>
request school:${requestScope.school }
<br><br>
sessiong school:${sessionScope.school }
<br><br>
</body>
</html>