路由约束:正则表达式
constraints
routes.MapRoute( name: "Default2", url: "gz-{controller}/{action}/{name}/{id}", defaults: new { controller = "Home", action = "HtmlHelper"}, constraints: new { id="[0-9]+" }//路由约束
namespaces: new string[1] { "S01Annotation.Controllers" }//去指定的命名空间查找方法
);