使用 NPOI 工作簿检索 MemoryStream 时引发 TaskCanceledException答案

【问题标题】：TaskCanceledException thrown on retrieving a MemoryStream with NPOI workbook使用 NPOI 工作簿检索 MemoryStream 时引发 TaskCanceledException
【发布时间】：2016-01-11 02:28:03
【问题描述】：

当我点击此 API 时，会抛出一个 TaskCanceledException 并带有无用的堆栈跟踪。我正在使用这个库：https://npoi.codeplex.com/

public class TestController : ApiController
    {
        [HttpGet]
        public HttpResponseMessage Test()
        {
            var templateWorkbook = new XSSFWorkbook();
            var sheet = templateWorkbook.CreateSheet("TestSheet");
            IRow dataRow = sheet.CreateRow(4);
            var cell = dataRow.CreateCell(0);
            cell.SetCellValue(77);

            Stream memoryStream = new MemoryStream();
            templateWorkbook.Write(memoryStream);

            var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StreamContent(memoryStream)
            };
            httpResponseMessage.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
            httpResponseMessage.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "test.xlsx" };
            return httpResponseMessage;
        }
    }

我做错了什么？这是我的堆栈跟踪：

[TaskCanceledException：任务已取消。]
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+165
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
System.Web.Http.Owin.d__20.MoveNext() +666
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+137
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd（任务任务）+25 System.Web.Http.Owin.d__0.MoveNext() +1814
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+137
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__5.MoveNext() +187 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +561
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+137
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
Microsoft.Owin.Security.Infrastructure.d__0.MoveNext() +561
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+137
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务) +58 Microsoft.Owin.Cors.d__0.MoveNext() +856
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+137
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__5.MoveNext() +187 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）+99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）+58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.d__2.MoveNext() +185 Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar) +69
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork（IAsyncResult ar) +64
System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +380 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

【问题讨论】：

您能否在您的问题中确定哪一行引发了异常？

标签： excel asp.net-web-api async-await task npoi

【解决方案1】：

我找到了解决办法。

将内存流复制到另一个并将查找位置重置为 0 似乎可以解决它：

MemoryStream memoryStream = new MemoryStream();
templateWorkbook.Write(memoryStream);
MemoryStream copy = new MemoryStream(memoryStream.ToArray());
copy.Seek(0, SeekOrigin.Begin);

对我来说，这似乎是 NPOI 库中的一个错误......

【讨论】：