"Stream不可读"与StreamReader一起使用ReadAsStreamAsync时出现ArgumentException

Question

我有以下代码来读取和处理使用StreamReader的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;
}

使用的行(StreamReader sr = new StreamReader(stream))是抛出类型为ArgumentException的ReadingStreamException的异常,其详细信息为"Stream is 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置时HttpResponseMessage,它会处理基础流.从来源:

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,也可以根本不进行处理HttpResponseMessage,因为在传递基础流时,无论如何都要处置它StreamReader.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;
}