从 blobBaseClient.DownloadToAsync 获取 FullContent

如何解决从 blobBaseClient.DownloadToAsync 获取 FullContent

我正在尝试使用 BlockBlobClient DownloadToAsync 方法下载 blob。 正如文档中提到的，我提供了必需的参数，但只获取了部分内容。 相关代码为：

            string messageJson = string.Empty;
            try
            {
                var blobBaseClient = new BlobBaseClient(_connectionString,_containerName,blobName);
                Stream stream = new MemoryStream();
                CancellationToken cancelToken = new CancellationToken();
                StorageTransferOptions storageTransferOptions = new StorageTransferOptions
                {
                    //bytes * 1000000 = MB
                    InitialTransferSize = blobInitialChunkSize.Value * 1000000,MaximumConcurrency = blobChunkUploadMaxThreadCount.Value,MaximumTransferSize = long.MaxValue
                };

                BlobRequestConditions blobRequestConditions = new BlobRequestConditions();
                Response response = await blobBaseClient.DownloadToAsync(stream,blobRequestConditions,storageTransferOptions,cancelToken);
                if(response.Status == Convert.ToInt32(HttpStatusCode.OK)
                {
                    using (StreamReader streamReader = new StreamReader(stream))
                    {
                        messageJson = streamReader.ReadToEnd();
                    }
                }
                else
                {
                    _logger.LogInformation("response.Headers.ContentType : " + response.Headers.ContentType + DateTime.Now.ToString());
                _logger.LogInformation("response.Headers.ContentLength : " + response.Headers.ContentLength + DateTime.Now.ToString());
                _logger.LogInformation("response.Headers.ETag : " + response.Headers.ETag + DateTime.Now.ToString());
                _logger.LogInformation("response.Headers.RequestId : " + response.Headers.RequestId + DateTime.Now.ToString());
                _logger.LogInformation("response.Status : " + response.Status + DateTime.Now.ToString());
                _logger.LogInformation("response.ReasonPhrase : " + response.ReasonPhrase + DateTime.Now.ToString());
                _logger.LogInformation("stream : " + stream + DateTime.Now.ToString());
        }
        catch (Exception ex)
        {
            _logger.LogInformation(ex.Message + " " + DateTime.Now.ToString());
            _logger.LogInformation(ex.StackTrace + " " + DateTime.Now.ToString());
            _logger.LogInformation(ex.Source + " " + DateTime.Now.ToString());
            _logger.LogInformation(ex.InnerException + " " + DateTime.Now.ToString());
            throw;
        }
        return messageJson;

我得到的结果是 else 块（不是异常）和日志值：

response.Headers.ContentType : application / octet - stream
response.Headers.ContentLength : 189778220
response.Headers.ETag : 0x8D860678531E07B
response.Status : 206
response.ReasonPhrase : Partial Content
stream: System.IO.MemoryStream
messageJson: 

我想知道如何获取完整数据而不是部分数据？任何指针/帮助将不胜感激。

解决方法

用 DownloadAsync 方法试试下面的代码，它会返回 200。

BlobServiceClient blobServiceClient = new BlobServiceClient(_connectionString);
BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(_containerName);
BlobClient blobClient = containerClient.GetBlobClient(blobName);
if (await blobClient.ExistsAsync())
{
    var response = await blobClient.DownloadAsync();
    using (var streamReader = new StreamReader(response.Value.Content))
    {
        while (!streamReader.EndOfStream)
        {
            var line = await streamReader.ReadLineAsync();
            Console.WriteLine(line);
        }
    }
    Console.WriteLine(response);
}

如果您使用 API 版本 2011-01-18 或更高版本，Azure Blob 存储支持返回 206 响应。正如 documentation 所说：

读取完整 blob 的成功操作返回状态代码 200 （好）。

读取指定范围的成功操作返回状态码 206（部分内容）。

,

正如我在 Github 上询问的 Bug 所建议的那样，我也为 HTTP 206 添加了成功条件，并且工作正常：

            if ((response.Status == Convert.ToInt32(HttpStatusCode.OK))
                || response.Status == Convert.ToInt32(HttpStatusCode.PartialContent))
            {
                using StreamReader streamReader = new StreamReader(response.ContentStream);
                stream.Position = 0;
                messageJson = streamReader.ReadToEnd();
            }