"stream was not readable" 将 ReadAsStreamAsync 与 StreamReader 一起使用时出现 ArgumentException

Question

我有以下代码使用 StreamReader 读取和处理 Http get 请求的响应：

try
{
    Stream stream = await ExecuteRequestAsync(uriBuilder.Uri, HttpMethod.Get).ConfigureAwait(false);
    if (stream != null)
    {
        using (StreamReader sr = new StreamReader(stream))
        {
            using (JsonTextReader reader = new JsonTextReader(sr))
            {
                ...
            }
        }
    }
}
catch (Exception ReadingStreamException)
{

}

private async Task<stream> ExecuteRequestAsync(Uri uri, HttpMethod method)
{
    Stream stream;
    using (HttpRequestMessage httpRequestMessage = new HttpRequestMessage(method, uri))
    {
    try
    {
        stopwatch.Start();
        using (HttpResponseMessage responseMessage = await this.httpClient.SendAsync(httpRequestMessage).ConfigureAwait(false))
        {
            stream = await responseMessage.Content.ReadAsStreamAsync().ConfigureAwait(false);
        }
    }
    catch(Exception GettingStreamException)
    {
        // Error checking code
    }

    return stream;
}

使用 (StreamReader sr = new StreamReader(stream)) 的行正在向类型为 ArgumentException 的 ReadingStreamException 抛出异常，详细信息为 "Stream was not readable"。上面的代码有问题吗？

Answer 1

发生这种情况是因为当您处理 HttpResponseMessage 时，它会处理基础流。来自 the source:

private HttpContent content;
protected virtual void Dispose(bool disposing)
{
    if (disposing && !disposed)
    {
        disposed = true;
        if (content != null)
        {
            content.Dispose();
        }
    }
}

您可以复制流，或者干脆不释放 HttpResponseMessage，因为在将它传递给 StreamReader 时，您无论如何都会释放底层流。我会选择后者：

private async Task<Stream> ExecuteRequestAsync(Uri uri, HttpMethod method)
{
    Stream stream = null;
    using (HttpRequestMessage httpRequestMessage = new HttpRequestMessage(method, uri))
    {
       try
       {
          stopwatch.Start();
          HttpResponseMessage responseMessage = await httpClient
                                                      .SendAsync(httpRequestMessage)
                                                      .ConfigureAwait(false);

          stream = await responseMessage.Content.ReadAsStreamAsync()
                                                .ConfigureAwait(false);
       }
       catch(Exception GettingStreamException)
       {
          // Error checking code
       }  
    }
    return stream;
}

"stream was not readable" 将 ReadAsStreamAsync 与 StreamReader 一起使用时出现 ArgumentException

"stream was not readable" ArgumentException when using ReadAsStreamAsync with StreamReader

c#

stream

streamreader

task-parallel-library

async-await