RouteConfig 中加一行代码：
routes.MapMvcAttributeRoutes(); 得加在第一行

 public static void RegisterRoutes(RouteCollection routes)
        {
            routes.MapMvcAttributeRoutes();

            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );


        }

控制器

public class HomeController : Controller
    {
        [Route("")]
        [Route("index")]
        public ActionResult Index()
        {
            return View();
        }

        [Route("aboutus")]

        public ActionResult Aboutus()
        {
            return View();
        }
    }

加了route属性的访问地址就成了这样：
http://localhost 对index
http://localhost/index 对index
http://localhost/aboutus 对aboutus

其他控制器访问还是 controller/action 的路由方式