一.SpringMVC的四种传值方式

1.传统Servlet进行传值

@ResquestMapping("demo1")
public String demo1(HttpServletRequest req,HttpSession session){
   req.setAttribute("req","req的值");
   HttpSession session=req.getSession();
   session.setAttribute("session","session的值");
   sessionParam.setAttribute("sessionParam","sessionParam的值")；
   ServletContext application=new ServletContext();
   application.setAttribute("application","application的值");
   return "/index.jsp";
}

2.通过Map传值（底层由request接口实现）

@RequestMapping("demo2")
public String demo2(Map<String,Object>map){
   map.put("map","map的值");
   return "/index.jsp";
}

3.使用SpringMVC中的Model接口传值

@RequestMapping("demo3")
public String demo3(Model model){
   model.setAttribute("model","model的值");
   return "/index.jsp";
}

4.使用SpringMVC中的ModelAndView接口传值（相当于Model+视图）

@RequestMapping("demo4")
public ModelAndView demo4(){
   //参数,跳转视图
   ModelAndView nav=new ModelAndView("/index.jsp");
   nav.addObject("nav","nav的值");
   return nav;
}

5.jsp代码

<body>
   request:${requestScope.req}
   session:${seesionScope.session}
   sessionParam:${sessionScope.sessionParam}
   application:${applicationScope.application}
   map:${requestScope.map}
   model:${model}
    
</body>