HttpClient.SendAsync throws ObjectDisposedException on Xamarin.Forms Android but not on UWP

问题

I'm writing a Xamarin.Forms application and I'm trying to do a Post to my webserver with some JSON payload.

This works fine in UWP, but on Android I get the following error:

 System.ObjectDisposedException: Can not access a closed Stream.
  at System.IO.StreamHelpers.ValidateCopyToArgs (System.IO.Stream source, System.IO.Stream destination, System.Int32 bufferSize) [0x0003a] in <19853c43ab794d18ab1a33ecb65b3c4d>:0 
  at System.IO.MemoryStream.CopyToAsync (System.IO.Stream destination, System.Int32 bufferSize, System.Threading.CancellationToken cancellationToken) [0x00000] in <19853c43ab794d18ab1a33ecb65b3c4d>:0 
  at Xamarin.Android.Net.AndroidClientHandler.WriteRequestContentToOutput (System.Net.Http.HttpRequestMessage request, Java.Net.HttpURLConnection httpConnection, System.Threading.CancellationToken cancellationToken) [0x0009a] in <2bd1b8f6e97f44bbb32ce356b78d4ce6>:0 
  at Xamarin.Android.Net.AndroidClientHandler.DoProcessRequest (System.Net.Http.HttpRequestMessage request, Java.Net.URL javaUrl, Java.Net.HttpURLConnection httpConnection, System.Threading.CancellationToken cancellationToken, Xamarin.Android.Net.AndroidClientHandler+RequestRedirectionState redirectState) [0x002f4] in <2bd1b8f6e97f44bbb32ce356b78d4ce6>:0 
  at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x002cf] in <2bd1b8f6e97f44bbb32ce356b78d4ce6>:0 
  at System.Net.Http.HttpClient.FinishSendAsyncBuffered (System.Threading.Tasks.Task`1[TResult] sendTask, System.Net.Http.HttpRequestMessage request, System.Threading.CancellationTokenSource cts, System.Boolean disposeCts) [0x0017e] in <c85119bf7e3e421490ae6b5487992fff>:0 
  at BB.App.Services.WebserviceHelper.PostToWebservice[T] (System.String url, System.String json) [0x0008d] in C:\_Sources\_BB\BB.App\BB.App\Services\WebserviceHelper.cs:74

This happens when the following code is executed:

await httpClient.SendAsync(httpRequest);

I found this site where it recommends not putting the creation of the HttpClient in a using statement, I changed this but it didn't fix my problem.

I also found this bug that is supposed to be fixed last year. To be honest this sounds like the most likely candidate but I don't know exactly what to update to get this fix on my pc. I already updated all my xamarin.android.x references in my solution but no luck so far.

回答1:

So in conclusion what fixed my problem was to

going to the properties of the android project,
selecting the 'android options' tab,
clicking 'advanced'
setting the 'httpclient implementation' from 'Android' to 'Managed'

来源：https://stackoverflow.com/questions/59933234/httpclient-sendasync-throws-objectdisposedexception-on-xamarin-forms-android-but

标签

android

Xamarin

xamarin.forms

dotnet-httpclient