我试图从一个从外部源检索的文件中读取字节,但是在运行代码时,我得到了以下错误: System.NotSupportedException: Specified method is not supported\r\n at System.Net.Http.HttpBaseStream.get_Length() 我正在讨论的代码如下: var responseBody = (request.GetResponseAsyncresult = new MemoryStream(file); 它在以下行失败: file = br.ReadBy