How to restrict access to the Java admin page?

I am writing a web service with an authorization and registration form. There are two types of users: regular and administrator. There is a controller that sends to the admin page at a given URL:

@Controller
public class ViewPageController {
    @RequestMapping(value = "/admin", method = RequestMethod.GET)
    public String sendAdminPage(){
        return "AdminPage";
    }
}

But ordinary users can also access this page. It is necessary that only those who logged in as an administrator get to the admin page. There are options for how this can be organized? Maybe save the logged in user in the session? (Preferably without Spring Security)