Question

更新时间03/28/2017：

这是我在iOS上运行的Xamarin PCL项目中的一段C＃代码。

public async Task<string> uploadPhoto(string imageBase64)
{

      string responseContent = null;
      var uri = new Uri(Constants.uploadImageUrl);

      try
      {
           StringContent stringContent = new StringContent("photo=;base64," + imageBase64, Encoding.UTF8, "application/x-www-form-urlencoded");

           var response = await client.PostAsync(uri, stringContent).ConfigureAwait(false); 

           // always check return success first
           if (response.IsSuccessStatusCode)
           {
                responseContent = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
           }
           else
           {
                return null;
           }


           if (responseContent.Contains("Failed"))
           {
               return null;
           }
       }
       catch (Exception ex)
       {
           Debug.WriteLine(@"uploadPhoto        ERROR {0}", ex.Message);
           if (ex.InnerException != null)
           {
               Debug.WriteLine(@"uploadPhoto        ERROR {0}", ex.InnerException.Message);
           }
           return null;
       }

       return responseContent;
}

client.PostAsync（）;

抛出的异常

[0：]无法访问已处置的对象。对象名称：＆＃39; System.Net.Sockets.NetworkStream＆＃39;

client.PostAsync（）有时会失败，我不容易复制此异常。我不知道为什么PostAsync（）会抛出这样的异常。我的互联网连接很好，uri和内容都经过验证。

问题是：

为什么PostAsync（）会在一切都很好的时候抛出这个异常？
System.Net.Sockets.NetworkStream如何在此例外中扮演角色？

我希望有人可以帮助回答这些问题，并希望能够提供一些指导和解决这个问题的方法。

更新

这是捕获的堆栈跟踪。 client.PostAsync（）抛出异常。

{System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Net.Sockets.NetworkStream'.
  at System.Net.WebConnectionStream.EndWrite (System.IAsyncResult r) [0x000d3] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/System/System.Net/WebConnectionStream.cs:616 
  at System.IO.Stream.<BeginEndWriteAsync>m__8 (System.IO.Stream stream, System.IAsyncResult asyncResult) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/io/stream.cs:729 
  at System.Threading.Tasks.TaskFactory`1+FromAsyncTrimPromise`1[TResult,TInstance].Complete (TInstance thisRef, System.Func`3[T1,T2,TResult] endMethod, System.IAsyncResult asyncResult, System.Boolean requiresSynchronization) [0x00002] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/threading/Tasks/FutureFactory.cs:1441 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:447 
  at System.Net.Http.HttpClientHandler+<SendAsync>c__async0.MoveNext () [0x00308] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:371 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in <54e129cad3ee4c61a6b46c3680ddc69a>:0 
  at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:276 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:143 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00047] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x0002e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x0000b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/10.4.0.123/src/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in <54e129cad3ee4c61a6b46c3680ddc69a>:0 
  at MyApp.RestService+<uploadPhoto>d__4.MoveNext () [0x00098] in D:\MyApp\MyApp\RestService.cs:147 }

无法访问HttpClient上的已处置对象（System.Net.Sockets.NetworkStream）

0 个答案: