一：(1.1)了解MVC之路由重写

//系统的Url路由规则
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Demo1", action = "Index", id = UrlParameter.Optional }
);
这是默认的 ，但是也不是默认的，因为默认的路由  controller = "Home"

我这里稍微改了下

 public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            //新建路由规则  小范围写在前面，大范围写在后面
            //否则将不会执行
　　　　　　　　//假如书写的路由规则放在默认规则之后，则不会执行
　            routes.MapRoute(
                name:"NewShow",
                url:"{year}/{month}/{day}",
                defaults:new { Controller="News" ,action= "Index" },
                //正则匹配
                //方法形参一致
                //http:xxx/News/2019-2-4
                constraints: new { year="^\\d{4}$", month = "^\\d{1,2}$" , day = "^\\d{1,2}$" }
                );

            //系统的Url路由规则
            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Demo1", action = "Index", id = UrlParameter.Optional }
            );
        }