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HttpClient c#-在SendASync上取消了任务

httpclient visual-studio wpf c#

djkpA · 技术社区 · 7 年前

TaskCanceledException 即使我增加超时。令人惊讶的是,它甚至不总是发生,异常只在某个时候发生,我无法找到模式来重现错误。我添加了异常跟踪和用于进行网络调用的代码。

public static void getResponseFromUrlAsync<T>(T payload, string url,
     Action<string> onSuccess, Action<string> onFailure)
{
    string contentType = "application/json";
    httpClient = new HttpClient();
    httpClient.Timeout = TimeSpan.FromMinutes(30);
    HttpRequestMessage requestMsg = new HttpRequestMessage();
    requestMsg.RequestUri = new Uri(NetworkCallUrls.baseUri + url);
    Utils.debugLog("Url", NetworkCallUrls.baseUri + url);

    // try
    //{
    string auth = "Bearer " + Objects.GlobalVars.GetValue<string>("access_token"); // //"x1VwaR1otS66ZCTlgtv3X9aaSNpDOn"; //
    httpClient.DefaultRequestHeaders.Add("Authorization", auth);
    requestMsg.Method = HttpMethod.Post;

    requestMsg.Content = new StringContent(
                   Utils.stringifyData(payload),
                   Encoding.UTF8,
                   contentType);

    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header

    makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction(requestMsg, onSuccess, onFailure, progressBarStatus);
}

internal static void disposeConnection(HttpClient httpClient)
{
    httpClient.Dispose();
    httpClient = null;
}

private static async void makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction(
    HttpRequestMessage requestMsg, Action<string> onSuccess,
    Action<string> onFailure, Action<bool> progressBarStatus)
{
    Utils.debugLog("IN MAKE NETWORK CALL 1");
    HttpResponseMessage response = await httpClient.SendAsync(requestMsg);
    Utils.debugLog("IN MAKE NETWORK CALL 2");
    ResponseStatus responseStatus = checkResponseStatusAndExecuteActionAccordinglyAsync(response);
    Utils.debugLog("IN MAKE NETWORK CALL 3");
    if (responseStatus.isSuccess)
    {
        Utils.debugLog("IN MAKE NETWORK CALL 4");
        string responseString = await response.Content.ReadAsStringAsync();
        Utils.debugLog("IN MAKE NETWORK CALL 5");
        onSuccess(responseString);
        Utils.debugLog("IN MAKE NETWORK CALL 6");
    }
    else
    {
        Utils.debugLog("IN MAKE NETWORK CALL 7");
        onFailure(responseStatus.failureResponse);
        Utils.debugLog("IN MAKE NETWORK CALL 8");
    }
    Utils.debugLog("IN MAKE NETWORK CALL 9");
    disposeConnection(httpClient);
    Utils.debugLog("IN MAKE NETWORK CALL 10");
}

我正在使用上述代码进行API调用,我正在获取TaskCanceledException HttpResponseMessage response = await httpClient.SendAsync(requestMsg); 线

有人能帮我解决这个问题吗。我在网上搜索,也增加了超时时间,但没有用。

2 回复 | 直到 7 年前

Tsahi Asher 7 年前

我希望一些评论能帮助您解决问题:

async 方法应返回 Task 如果你没有东西要还,不要 void 任务 对象,编译器将处理此问题。唯一的例外是WinForms和WebForms事件处理程序。
你的 getResponseFromUrlAsync 方法不是异步的,但它应该是异步的。您应该添加一个 异步 修饰符,并返回 . 然后 await makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction(...) . 这可能是问题的根源-您没有等待异步操作在返回之前完成。
总的来说,你的 httpClient makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction 即使不呼叫也可以呼叫 getResponseFromUrlAsync 首先,我们也可以 disposeConnection . 如果您的类始终使用 httpClient

mm8 7 年前

你应该等待 makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction 方法和 getResponseFromUrlAsync 方法这意味着您需要将返回类型从 void 到 Task :

public static async Task getResponseFromUrlAsync<T>(T payload, string url, Action<string> onSuccess, Action<string> onFailure)
{
    string contentType = "application/json";
    httpClient = new HttpClient();
    httpClient.Timeout = TimeSpan.FromMinutes(30);
    HttpRequestMessage requestMsg = new HttpRequestMessage();
    requestMsg.RequestUri = new Uri(NetworkCallUrls.baseUri + url);
    Utils.debugLog("Url", NetworkCallUrls.baseUri + url);


    string auth = "Bearer " + Objects.GlobalVars.GetValue<string>("access_token"); // //"x1VwaR1otS66ZCTlgtv3X9aaSNpDOn"; //
    httpClient.DefaultRequestHeaders.Add("Authorization", auth);
    requestMsg.Method = HttpMethod.Post;

    requestMsg.Content = new StringContent(
                   Utils.stringifyData(payload),
                   Encoding.UTF8,
                   contentType);

    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header

    await makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction(requestMsg, onSuccess, onFailure, progressBarStatus)
        .ConfigureAwait(false);
}

internal static void disposeConnection(HttpClient httpClient)
{
    httpClient.Dispose();
    httpClient = null;
}

private static async Task makeNetworkCallCheckResponseStatusAndExecuteCorrospondingAction(
    HttpRequestMessage requestMsg, Action<string> onSuccess,
    Action<string> onFailure, Action<bool> progressBarStatus)
{
    Utils.debugLog("IN MAKE NETWORK CALL 1");
    HttpResponseMessage response = await httpClient.SendAsync(requestMsg).ConfigureAwait(false);
    Utils.debugLog("IN MAKE NETWORK CALL 2");
    ResponseStatus responseStatus = checkResponseStatusAndExecuteActionAccordinglyAsync(response);
    Utils.debugLog("IN MAKE NETWORK CALL 3");
    if (responseStatus.isSuccess)
    {
        Utils.debugLog("IN MAKE NETWORK CALL 4");
        string responseString = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
        Utils.debugLog("IN MAKE NETWORK CALL 5");
        onSuccess(responseString);
        Utils.debugLog("IN MAKE NETWORK CALL 6");
    }
    else
    {
        Utils.debugLog("IN MAKE NETWORK CALL 7");
        onFailure(responseStatus.failureResponse);
        Utils.debugLog("IN MAKE NETWORK CALL 8");
    }
    Utils.debugLog("IN MAKE NETWORK CALL 9");
    disposeConnection(httpClient);
    Utils.debugLog("IN MAKE NETWORK CALL 10");
}

...和 await 调用时的方法:

await getResponseFromUrlAsync<..>(...);