实现IActionResult筛选器运行时错误

我正在尝试实现这个例子：

堆栈溢出

但是，当我的ASP.NET MVC4应用程序在代码filterContext.RequestContext.HttpContext.Response.Filter = new CdnResponseFilter(filterContext.RequestContext.HttpContext.Response.Filter);行的第一个Action异常消息之后执行任何操作时，它都会不断抛出Filtering is not allowed。

根据一些搜索，我尝试将过滤器移动到另一个事件函数，但都没有成功。我还尝试过检查过滤器是否已经应用，如果已经应用，请不要添加新的过滤器。

第一个操作经过了适当的过滤，在执行第二个操作时抛出异常。

代码

public class CDNUrlFilter : IActionFilter, IResultFilter
{
    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
    }
    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        filterContext.RequestContext.HttpContext.Response.Filter = new CdnResponseFilter(filterContext.RequestContext.HttpContext.Response.Filter);
    }
    public void OnResultExecuting(ResultExecutingContext filterContext)
    { 
    }
    public void OnResultExecuted(ResultExecutedContext filterContext)
    { 
    }
}
public class CdnResponseFilter : MemoryStream
{
    private Stream Stream { get; set; }
    public CdnResponseFilter(Stream stream)
    {
        Stream = stream;
    }
    public override void Write(byte[] buffer, int offset, int count)
    {
        var data = new byte[count];
        Buffer.BlockCopy(buffer, offset, data, 0, count);
        string html = Encoding.Default.GetString(buffer);
        html = Regex.Replace(html, "src='"/Content/([^'"]+)'"", FixUrl, RegexOptions.IgnoreCase);
        html = Regex.Replace(html, "href='"/Content/([^'"]+)'"", FixUrl, RegexOptions.IgnoreCase);
        html = Regex.Replace(html, "src='"/Images/([^'"]+)'"", FixUrl, RegexOptions.IgnoreCase);
        html = Regex.Replace(html, "href='"/Images/([^'"]+)'"", FixUrl, RegexOptions.IgnoreCase);
        byte[] outData = Encoding.Default.GetBytes(html);
        Stream.Write(outData, 0, outData.GetLength(0));
    }
    private static string FixUrl(Match match)
    {
        if (match.ToString().Contains("src"))
        {
            return String.Format("{0}", match.ToString());
        }
        else if (match.ToString().Contains("href"))
        {
            return String.Format("href='"{0}content{1}", Settings.Default.CDNDomain, match.ToString().Replace("href='"", ""));
        }
        return match.ToString();
    }
}

根据要求，这里是从Global.asax.cs:调用的RegisterGlobalFilters

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new HandleErrorAttribute());
        filters.Add(new Filters.InitializeSimpleMembershipAttribute());
        filters.Add(new Filters.RequestTimingFilter());
        if (Settings.Default.CDNEnable)
        {
            filters.Add(new Filters.CDNUrlFilter());
        }
    }
}

添加完整堆栈跟踪的另一个编辑：

Stack Trace
at System.Web.HttpResponse.set_Filter(Stream value) 
at POSGuys.Filters.CDNUrlFilter.OnActionExecuted(ActionExecutedContext filterContext) in c:'Users'skatir'Documents'BitBucket'posguys'Filters'CDNUrlFilter.cs:line 20 
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49() 
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49() 
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49() 
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.b__36(IAsyncResult asyncResult) 
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<>c__DisplayClass2a.b__20()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.b__22(IAsyncResult asyncResult) 
at System.Web.Mvc.Controller.<>c__DisplayClass1d.b__18(IAsyncResult asyncResult) 
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) 
at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) 
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) 
at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) 
at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__3(IAsyncResult asyncResult) 
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) 
at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) 
at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.b__3() 
at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func) 
at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)

Target Site
Void set_Filter(System.IO.Stream)

在试图解决这个问题时，我偶然发现了一件非常奇怪的事情，那就是如果我将OnActionExecute中的Response.Filter的设置包装在try｛｝catch｛｝｝块中，则页面将正确地使用过滤器进行渲染。这让我觉得系统的其他部分正在尝试过滤不应该过滤的内容。我将在调试器中做一些工作，看看是否不能从这里缩小范围。

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        if (Settings.Default.CDNEnable)
        {
            filters.Add(new Filters.CDNUrlFilter());
        }
        filters.Add(new HandleErrorAttribute());
        filters.Add(new Filters.InitializeSimpleMembershipAttribute());
        filters.Add(new Filters.RequestTimingFilter());
    }
}