http://localhost:8080/um/view?userId=1

显示报错500：Could not resolve view with name '/um/view.jsp' in servlet with name 'springmvc'

http://localhost:8080/um/view.jsp?userId=1就显示

I'm view page(/um/view.jsp)

Username:（空）

这是控制层部分代码：

@GetMapping("/view")
@ResponseBody
public ModelAndView showView(Integer userId){
   ModelAndView mav = new ModelAndView("/view.jsp");
   User user = new User();
   if(userId == 1){
       user.setUsername("lily");
   }else if(userId == 2){
       user.setUsername("smith");
   }else if(userId == 3){
       user.setUsername("lina");
   }
   mav.addObject("u" , user);
   return mav;
}

其他代码和老师的源码一样