c# - CancellationToken.ThrowOperationCanceledException异常

Question

我的 Xamarin.Forms 项目出现以下错误:

  at System.Threading.CancellationToken.ThrowOperationCanceledException () [0x00010] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.CancellationToken.ThrowIfCancellationRequested () [0x00008] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass44_0.<ConnectAsync>b__0 () [0x0004f] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:343 
  at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.Tasks.Task.Execute () [0x00000] in <46c2fa109b574c7ea6739f9fe2350976>:0 
--- End of stack trace from previous location where exception was thrown ---

  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) [0x000e4] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:393 
  at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00285] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:286 
  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 <814c177e4f174da89876fafdde15d02e>:0 
  at BUCOLogin.Constants.RestService.GetBranchesAsync (System.String uri) [0x00047] in C:\VST\BFR Login\Login\Constants\RestService.cs:23 }

经过一些调查后，似乎一个 token 被取消了，但我不确定这个 token 位于何处，甚至不确定它被取消的原因。我正在使用不需要 APIKey 的开放 API 请求:

常量.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace BUCOLogin.Constants
{
    public static class Constants
    {
        public const string OpenBabbageEndpoint = "http://IP/ILDTEST/XI/Core/GetBranches";
        //public const string OpenBabbageAPIKey = "f6a04a6c3fbc534c295f6a5e8548e0f6";
    }
}

单步执行代码时，它会在以下代码处停顿/等待一段时间，然后再给我异常:

string content = await response.Content.ReadAsStringAsync();

此代码位于 RestService.cs 中:

using System;
using System.Diagnostics;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace BUCOLogin.Constants
{
    public class RestService
    {
        HttpClient _client;

        public RestService()
        {
            _client = new HttpClient();
        }

        public async Task<GetBranches> GetBranchesAsync(string uri)
        {
            GetBranches branchesData = null;
            try
            {
                HttpResponseMessage response = await _client.GetAsync(uri);
                if (response.IsSuccessStatusCode)
                {
                    string content = await response.Content.ReadAsStringAsync();
                    branchesData = JsonConvert.DeserializeObject<GetBranches>(content);
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine("\tERROR {0}", ex.Message);
            }

            return branchesData;
        }
    }
}

GetBranches.cs:

using System;
using System.Collections.Generic;
using System.Text;

using Newtonsoft.Json;

namespace BUCOLogin.Constants
{
    public class GetBranches
    {

        [JsonProperty("name")]
        public string Name { get; set; }

        [JsonProperty("number")]
        public string Number { get; set; }

        [JsonProperty("postcode")]
        public string Postcode { get; set; }

        [JsonProperty("manager")]
        public string Manager { get; set; }

        [JsonProperty("phone")]
        public string Phone { get; set; }

        [JsonProperty("address")]
        public string Address { get; set; }

        [JsonProperty("open")]
        public string Open { get; set; }

        [JsonProperty("close")]
        public string Close { get; set; }

        [JsonProperty("opensat")]
        public string Opensat { get; set; }

        [JsonProperty("closesat")]
        public string Closesat { get; set; }

    }
}

uri 请求确实会在 Postman 上返回结果，所以我不确定为什么会收到此异常以及如何继续。

提前致谢。

更新

使用@Nkosi 代码更新 RestService.cs 后，出现以下错误:

{System.OperationCanceledException: The operation was canceled.
  at System.Threading.CancellationToken.ThrowOperationCanceledException () [0x00010] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.CancellationToken.ThrowIfCancellationRequested () [0x00008] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass44_0.<ConnectAsync>b__0 () [0x0004f] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:343 
  at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.Tasks.Task.Execute () [0x00000] in <46c2fa109b574c7ea6739f9fe2350976>:0 
--- End of stack trace from previous location where exception was thrown ---

  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) [0x000e4] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:393 
  at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00285] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:286 
  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 <814c177e4f174da89876fafdde15d02e>:0 
  at BUCOLogin.Constants.RestService.GetBranchesAsync (System.String uri) [0x00046] in C:\Visual Studio Training\BUCO FR Login\FacialRecognitionLogin\Constants\RestService.cs:18 }

更新 2

添加 _client.Timeout = TimeSpan.FromSeconds(300); 后:

{Java.Net.SocketTimeoutException: failed to connect to /IP (port 791) from /IP (port 60644) after 86400000ms: isConnected failed: ETIMEDOUT (Connection timed out) ---> Android.Systems.ErrnoException: isConnected failed: ETIMEDOUT (Connection timed out)
   --- End of inner exception stack trace ---
  at Java.Interop.JniEnvironment+InstanceMethods.CallVoidMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x00069] in <dec6115f7d4449ee8ce1bcacaa8cb579>:0 
  at Java.Interop.JniPeerMembers+JniInstanceMethods.InvokeAbstractVoidMethod (System.String encodedMember, Java.Interop.IJavaPeerable self, Java.Interop.JniArgumentValue* parameters) [0x00014] in <dec6115f7d4449ee8ce1bcacaa8cb579>:0 
  at Java.Net.HttpURLConnectionInvoker.Connect () [0x00000] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/obj/Release/android-28/mcw/Java.Net.HttpURLConnection.cs:714 
  at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass44_0.<ConnectAsync>b__0 () [0x0005a] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:344 
  at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in <46c2fa109b574c7ea6739f9fe2350976>:0 
  at System.Threading.Tasks.Task.Execute () [0x00000] in <46c2fa109b574c7ea6739f9fe2350976>:0 
--- End of stack trace from previous location where exception was thrown ---

  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) [0x000e4] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:393 
  at Xamarin.Android.Net.AndroidClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x00285] in /Users/vsts/agent/2.155.1/work/1/s/src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs:286 
  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 <814c177e4f174da89876fafdde15d02e>:0 
  at BUCOLogin.Constants.RestService.GetBranchesAsync (System.String uri) [0x00066] in C:\Visual Studio Training\BUCO FR Login\FacialRecognitionLogin\Constants\RestService.cs:21 
  --- End of managed Java.Net.SocketTimeoutException stack trace ---
java.net.SocketTimeoutException: failed to connect to /IP (port 791) from /IP (port 60644) after 86400000ms: isConnected failed: ETIMEDOUT (Connection timed out)
    at libcore.io.IoBridge.isConnected(IoBridge.java:276)
    at libcore.io.IoBridge.connectErrno(IoBridge.java:187)
    at libcore.io.IoBridge.connect(IoBridge.java:129)
    at java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:137)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:391)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:231)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:213)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)
    at java.net.Socket.connect(Socket.java:621)
    at com.android.okhttp.internal.Platform.connectSocket(Platform.java:145)
    at com.android.okhttp.internal.io.RealConnection.connectSocket(RealConnection.java:141)
    at com.android.okhttp.internal.io.RealConnection.connect(RealConnection.java:112)
    at com.android.okhttp.internal.http.StreamAllocation.findConnection(StreamAllocation.java:184)
    at com.android.okhttp.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:126)
    at com.android.okhttp.internal.http.StreamAllocation.newStream(StreamAllocation.java:95)
    at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:281)
    at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:224)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:461)
    at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:127)
Caused by: android.system.ErrnoException: isConnected failed: ETIMEDOUT (Connection timed out)
    at libcore.io.IoBridge.isConnected(IoBridge.java:267)
    ... 18 more
}

Answer 1

您可以尝试增加 HttpClient.Timeout 以避免 OperationCanceledException。

为了

Java.Net.SocketTimeoutException: failed to connect to /IP (port 791) from /IP (port 60644) after 86400000ms: isConnected failed: ETIMEDOUT (Connection timed out) ---> Android.Systems.ErrnoException: isConnected failed: ETIMEDOUT (Connection timed out)

确保您的设备可以通过网络访问它所连接的 IP/端口。