这种方法有效。 我建议将其切换为显式处理exception（包括您的超时，但也包括坏域名等）略有不同。 在这种情况下，我将其拆分为一个单独的延续。

另外，为了使这一点非常明确，我缩短了超时时间，放入了一个“真实”但速度较慢的域，并添加了一个明确的超时状态，你可以看到：

 using System; using System.IO; using System.Net; using System.Threading; using System.Threading.Tasks; class HttpSocket { private const int TimeoutLength = 100; public static void MakeRequest(Uri uri, Action responseCallback) { WebRequest request = WebRequest.Create(uri); request.Proxy = null; Task asyncTask = Task.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, null); ThreadPool.RegisterWaitForSingleObject((asyncTask as IAsyncResult).AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), request, TimeoutLength, true); asyncTask.ContinueWith(task => { WebResponse response = task.Result; Stream responseStream = response.GetResponseStream(); responseCallback(new RequestCallbackState(response.GetResponseStream())); responseStream.Close(); response.Close(); }, TaskContinuationOptions.NotOnFaulted); // Handle errors asyncTask.ContinueWith(task => { var exception = task.Exception; var webException = exception.InnerException; // Track whether you cancelled or not... up to you... responseCallback(new RequestCallbackState(exception.InnerException, webException.Message.Contains("The request was canceled."))); }, TaskContinuationOptions.OnlyOnFaulted); } private static void TimeoutCallback(object state, bool timedOut) { Console.WriteLine("Timeout: " + timedOut); if (timedOut) { Console.WriteLine("Timeout"); WebRequest request = (WebRequest)state; if (state != null) { request.Abort(); } } } } class RequestCallbackState { public Stream ResponseStream { get; private set; } public Exception Exception { get; private set; } public bool RequestTimedOut { get; private set; } public RequestCallbackState(Stream responseStream) { ResponseStream = responseStream; } public RequestCallbackState(Exception exception, bool timedOut = false) { Exception = exception; RequestTimedOut = timedOut; } } class RequestState { public byte[] RequestBytes { get; set; } public WebRequest Request { get; set; } public Action ResponseCallback { get; set; } } class Program { static void Main(string[] args) { // Making a request to a nonexistent domain. HttpSocket.MakeRequest(new Uri("https://www.tanzaniatouristboard.com/"), callbackState => { if (callbackState.RequestTimedOut) { Console.WriteLine("Timed out!"); } else if (callbackState.Exception != null) throw callbackState.Exception; else Console.WriteLine(GetResponseText(callbackState.ResponseStream)); }); Thread.Sleep(100000); } public static string GetResponseText(Stream responseStream) { using (var reader = new StreamReader(responseStream)) { return reader.ReadToEnd(); } } } 

这将运行，并适当显示超时。

使用2个不同的类：

 class RequestCallbackException : Exception { public RequestCallbackException(Stream responseStream, Exception exception) : base(exception) { } } 

和

 class RequestCallbackStream { public Stream ResponseStream { get; private set; } public RequestCallbackState(Stream responseStream) { ResponseStream = responseStream; } } 

您会注意到有时GetResponseStream（）会返回null，这会立即引发exception

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 asyncTask.ContinueWith() --> GetResponseText(callbackState.ResponseStream)--> using (var reader = new StreamReader(responseStream)) // responseStream is null { }