spring MVC 如何獲取session並實現傳值到前台

以前經常使用SSH框架，對spring MVC只是有所了解，但是當真正使用springMVC做開發的時候卻發現，一個簡單的獲取session的問題竟然糾結了許久：

花點時間記錄一下，以便日后重用：

后台獲取session：

@RequestMapping("/usrlogin")
public ModelAndView usrlogin(@RequestParam String usrid,
            @RequestParam String passwd) {
        HttpSession session = getSession();
        User user = new User();
        user = userMapper.getUserByUsridAndPasswd(usrid, passwd);
        if (null != user) {
            session.setAttribute("user", user.getUser_id());
//            User user1=(User)session.getAttribute("user");
//            System.out.println(user1.getUser_name());
            
            return new ModelAndView("main");
        } else {
            return new ModelAndView("error");
        }
    }
       
       
public static HttpSession getSession() { 
    HttpSession session = null; 
    try { 
        session = getRequest().getSession(); 
    } catch (Exception e) {} 
        return session; 
} 
    
public static HttpServletRequest getRequest() { 
    ServletRequestAttributes attrs =(ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); 
    return attrs.getRequest(); 
} 

前台jsp取值：

 <%
        HttpSession s = request.getSession();     
  %>

<span><%=s.getAttribute("user")%></span>