用于错误处理和丢失图像的httpmodule

最终,问题是由于没有区分传统ASP.NET应用程序和ASP.NET MVC应用程序提供的不同类型的上下文。通过提供一个检查来确定我正在处理的上下文类型,我能够做出相应的响应。

我为httptransfer和mvctransfer添加了单独的方法,允许我重定向到错误页面,特别是在需要时。我还改变了周围的逻辑,这样我就可以很容易地在本地和开发机器上获得我的ysod,而不需要处理程序接受异常。

除了用于将异常记录到数据库的代码(由todo注释表示)之外,我们使用的最终代码是:

using System;
using System.Net;
using System.Security.Principal;
using System.Web;
using System.Web.Configuration;
using System.Web.Mvc;

using Diagnostics;

/// <summary>
/// Provides a standardized mechanism for handling exceptions within a web application.
/// </summary>
public sealed class ErrorHandlerModule : IHttpModule
{
    #region Public Methods

    /// <summary>
    /// Disposes of the resources (other than memory) used by the module that implements 
    /// <see cref="T:System.Web.IHttpModule"/>.
    /// </summary>
    public void Dispose()
    {
    }

    /// <summary>
    /// Initializes a module and prepares it to handle requests.
    /// </summary>
    /// <param name="context">
    /// An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events 
    /// common to all application objects within an ASP.NET application.</param>
    public void Init(HttpApplication context)
    {
        context.Error += OnError;
    }

    #endregion

    #region Private Static Methods

    /// <summary>
    /// Performs a Transfer for an MVC request.
    /// </summary>
    /// <param name="url">The URL to transfer to.</param>
    /// <param name="currentContext">The current context.</param>
    private static void HttpTransfer(string url, HttpContext currentContext)
    {
        currentContext.Server.TransferRequest(url);
    }

    /// <summary>
    /// Performs a Transfer for an MVC request.
    /// </summary>
    /// <param name="url">The URL to transfer to.</param>
    /// <param name="currentContext">The current context.</param>
    private static void MvcTransfer(string url, HttpContext currentContext)
    {
        var uriBuilder = new UriBuilder(
            currentContext.Request.Url.Scheme,
            currentContext.Request.Url.Host,
            currentContext.Request.Url.Port,
            currentContext.Request.ApplicationPath);

        uriBuilder.Path += url;

        string path = currentContext.Server.UrlDecode(uriBuilder.Uri.PathAndQuery);
        HttpContext.Current.RewritePath(path, false);
        IHttpHandler httpHandler = new MvcHttpHandler();

        httpHandler.ProcessRequest(HttpContext.Current);
    }

    #endregion

    #region Private Methods

    /// <summary>
    /// Called when an error occurs within the application.
    /// </summary>
    /// <param name="source">The source.</param>
    /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
    private static void OnError(object source, EventArgs e)
    {
        var httpContext = HttpContext.Current;
        var lastException = HttpContext.Current.Server.GetLastError().GetBaseException();
        var httpException = lastException as HttpException;
        var statusCode = (int)HttpStatusCode.InternalServerError;

        if (httpException != null)
        {
            if (httpException.Message == "File does not exist.")
            {
                httpContext.Response.StatusCode = (int)HttpStatusCode.NotFound;
                httpContext.ClearError();
                return;
            }

            statusCode = httpException.GetHttpCode();
        }

        if ((statusCode != (int)HttpStatusCode.NotFound) && (statusCode != (int)HttpStatusCode.ServiceUnavailable))
        {
            // TODO : Your error logging code here.
        }

        var redirectUrl = string.Empty;

        if (!httpContext.IsCustomErrorEnabled)
        {
            return;
        }

        var errorsSection = WebConfigurationManager.GetSection("system.web/customErrors") as CustomErrorsSection;
        if (errorsSection != null)
        {
            redirectUrl = errorsSection.DefaultRedirect;

            if (httpException != null && errorsSection.Errors.Count > 0)
            {
                var item = errorsSection.Errors[statusCode.ToString()];

                if (item != null)
                {
                    redirectUrl = item.Redirect;
                }
            }
        }

        httpContext.Response.Clear();
        httpContext.Response.StatusCode = statusCode;
        httpContext.Response.TrySkipIisCustomErrors = true;
        httpContext.ClearError();

        if (!string.IsNullOrEmpty(redirectUrl))
        {
            var mvcHandler = httpContext.CurrentHandler as MvcHandler;
            if (mvcHandler == null)
            {
                try
                {
                    HttpTransfer(redirectUrl, httpContext);
                }
                catch (InvalidOperationException)
                {
                    MvcTransfer(redirectUrl, httpContext);
                }
            }
            else
            {
                MvcTransfer(redirectUrl, httpContext);
            }
        }
    }

    #endregion
}

为什么不在你的global.asax中找到404?

protected void Application_Error(object sender, EventArgs args) {

    var ex = Server.GetLastError() as HttpException;
    if (ex != null && ex.ErrorCode == -2147467259) {

    }
}

如果我理解正确,您只想为导致404的操作处理错误?

您可以检查请求的路由是否为空或停止路由-这基本上是URL路由处理程序的工作方式,以决定请求是否应继续进入MVC管道。

var iHttpContext = new HttpContextWrapper( httpContext );
var routeData = RouteTable.Routes.GetRouteData( iHttpContext );
if( routeData == null || routeData.RouteHandler is StopRoute )
{
  // This is a route that would not normally be handled by the MVC pipeline
  httpContext.ClearError();
  return;
}

另外,由于404的重定向会导致用户体验不理想,这是ASP.NET的遗留问题(在这里,您无法将视图处理与请求处理分开)。管理404的正确方法是将404状态代码返回到浏览器并显示自定义错误页,而不是重定向(这将导致302状态代码发送到浏览器)。