在实际的项目中，会存在大量的自定义路由，URL很容易被错误的路由捕获，现在我们就实现一个这样的诊断工具，该工具通过实现一个自定义的IHttpModule来实现。

首先，我们创建CustomRouteHandler：

    public class CustomRouteHandler : IRouteHandler{public IHttpHandler GetHttpHandler(RequestContext requestContext){if(HasQueryStringKey("routeInfo", requestContext.HttpContext.Request)){OutputRouteDiagnostics(requestContext.RouteData, requestContext.HttpContext);}var handler = new CustomMvcHandler(requestContext);            return handler;}private bool HasQueryStringKey(string keyToTest, HttpRequestBase request){return Regex.IsMatch(request.Url.Query, string.Format(@"^\?{0}$", keyToTest));}private void OutputRouteDiagnostics(RouteData routeData, HttpContextBase context){var response = context.Response;response.Write(@"<style>body {font-family: Arial;}table th {background-color: #359; color: #fff;}</style><h1>Route Data:</h1><table border='1' cellspacing='0' cellpadding='3'><tr><th>Key</th><th>Value</th></tr>");foreach (var pair in routeData.Values){response.Write(string.Format("<tr><td>{0}</td><td>{1}</td></tr>", pair.Key, pair.Value));}response.Write(@"</table><h1>Routes:</h1><table border='1' cellspacing='0' cellpadding='3'><tr><th></th><th>Route</th></tr>");bool foundRouteUsed = false;foreach(Route r in RouteTable.Routes){response.Write("<tr><td>");bool matches = r.GetRouteData(context) != null;string backgroundColor = matches ? "#bfb" : "#fbb";if(matches && !foundRouteUsed){response.Write("&raquo;");foundRouteUsed = true;    }response.Write(string.Format("</td><td style='font-family: Courier New; background-color:{0}'>{1}</td></tr>",backgroundColor, r.Url));                }response.End();}}

CustomRouteHandler中使用到了一个CustomMvcHandler，如下：

    public class CustomMvcHandler : MvcHandler{public CustomMvcHandler(RequestContext requestContext): base(requestContext){}protected override void ProcessRequest(HttpContext httpContext){try{base.ProcessRequest(httpContext);}catch (Exception exc){throw new ApplicationException("RouteUsed:" +RequestContext.RouteData.Route.GetVirtualPath(RequestContext, RequestContext.RouteData.Values), exc);}}}

其次，我们需要在MapRoute的时候指定CustomRouteHandler，如下：

            routes.MapRoute("Default", // Route name"Home/{action}/{id}", // URL with parametersnew { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults).RouteHandler = new CustomRouteHandler();

最终的结果，如果我们想要看当前URL的路由信息，则输入URL如：http://localhost:12205/Home?routeInfo，会显式如下：