DashboardRoutes.Routes.AddRazorPage的内部源码如下：
public void AddRazorPage(string pageName, string viewPath, string routeTemplate)
{

// Get the route builder 
var routeBuilder = new RouteBuilder(this.ServiceProvider); 

// Set the page handler 
routeBuilder.AddPageRoute(pageName, viewPath, routeTemplate); 

// Add the routes to the collection of routes 
this.Routes.Add(routeBuilder.Build());  

}