ASP.NET MVC 利用 IHttpModule 实现路由调试

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：

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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("»");                 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：

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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。

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

如果我们想要看当前URL的路由信息，则输入 URL 如：http://localhost:8080/Home?routeInfo，就会显示路由信息了。