ASP.NET MVC – 使用Reflection查找控制器是否存在

发布时间：2020-12-16 03:24:08 所属栏目：asp.Net 来源：网络整理

导读：我有一点时间搞清楚如何正确实现我的404重定向. 如果我使用以下内容 HandleError() _Public Class BaseController : Inherits System.Web.Mvc.Controller''# do stuffEnd Class 然后页面上任何未处理的错误将加载“错误”视图,该视图效果很好. http://exampl

我有一点时间搞清楚如何正确实现我的404重定向.

如果我使用以下内容

<HandleError()> _
Public Class BaseController : Inherits System.Web.Mvc.Controller
''# do stuff
End Class

然后页面上任何未处理的错误将加载“错误”视图,该视图效果很好. http://example.com/user/999(其中999是无效的用户ID)将在保持原始URL时抛出错误(这是我想要的)

然而.如果有人将http://example.com/asdfjkl输入到url(其中asdfjkl是无效的控制器),则IIS将抛出通用404页面. (这不是我想要的).我需要的是上面要应用的相同内容.原始URL保留,并加载“NotFound”控制器.

我正在注册这样的路线

Shared Sub RegisterRoutes(ByVal routes As RouteCollection)
    routes.RouteExistingFiles = False
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}")
    routes.IgnoreRoute("Assets/{*pathInfo}")
    routes.IgnoreRoute("{*robotstxt}",New With {.robotstxt = "(.*/)?robots.txt(/.*)?"})

    routes.AddCombresRoute("Combres")

    routes.MapRoute("Start","",New With {.controller = "Events",.action = "Index"})

    ''# MapRoute allows for a dynamic UserDetails ID
    routes.MapRouteLowercase("UserProfile","Users/{id}/{slug}",_
                             New With {.controller = "Users",.action = "Details",.slug = UrlParameter.Optional},_
                             New With {.id = "d+"} _
    )


    ''# Default Catch All MapRoute
    routes.MapRouteLowercase("Default","{controller}/{action}/{id}/{slug}",_
                             New With {.controller = "Events",.action = "Index",.id = UrlParameter.Optional,_
                             New With {.controller = New ControllerExistsConstraint})

    ''# Catch everything else cuz they're 404 errors
    routes.MapRoute("CatchAll","{*catchall}",_
                    New With {.Controller = "Error",.Action = "NotFound"})

End Sub

注意ControllerExistsConstraint？我需要做的是使用Reflection来发现控制器是否存在.

任何人都可以帮我填空吗？

Public Class ControllerExistsConstraint : Implements IRouteConstraint

    Public Sub New()
    End Sub

    Public Function Match(ByVal httpContext As System.Web.HttpContextBase,ByVal route As System.Web.Routing.Route,ByVal parameterName As String,ByVal values As System.Web.Routing.RouteValueDictionary,ByVal routeDirection As System.Web.Routing.RouteDirection) As Boolean Implements System.Web.Routing.IRouteConstraint.Match


        ''# Bah,I can't figure out how to find if the controller exists


End Class

我也想知道这个性能的影响……性能如何重要反思？如果它太多了,有没有更好的方法？

解决方法

我有一个C#解决方案,我希望它有所帮助.我抄袭了一些代码,虽然对于我的生活,我找不到我从哪里得到它.如果有人知道,请告诉我,以便我可以将其添加到我的评论中.

此解决方案不使用反射,但它查看所有应用程序错误(异常)并检查它是否是404错误.如果是,那么它只是将当前请求路由到不同的控制器.虽然我不是任何方面的专家,但我认为这个解决方案可能比反思更快.无论如何,这是解决方案,它进入你的Global.asax.cs,

protected void Application_Error(object sender,EventArgs e)
    {
        Exception exception = Server.GetLastError();

        // A good location for any error logging,otherwise,do it inside of the error controller.

        Response.Clear();
        HttpException httpException = exception as HttpException;
        RouteData routeData = new RouteData();
        routeData.Values.Add("controller","YourErrorController");

        if (httpException != null)
        {
            if (httpException.GetHttpCode() == 404)
            {
                routeData.Values.Add("action","YourErrorAction");

                // We can pass the exception to the Action as well,something like
                // routeData.Values.Add("error",exception);

                // Clear the error,we will always get the default error page.
                Server.ClearError();

                // Call the controller with the route
                IController errorController = new ApplicationName.Controllers.YourErrorController();
                errorController.Execute(new RequestContext(new HttpContextWrapper(Context),routeData));
            }
        }
    }

所以控制器会,

public class YourErrorController : Controller
{
    public ActionResult YourErrorAction()
    {
        return View();
    }
}

（编辑：李大同）

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