使用 Uri 下载 blob 时出现错误“404 指定的 blob 不存在”

Question

我尝试在服务总线主题触发 Azure 函数中使用 blob url 下载 blob，但出现以下错误：

Status: 404 (The specified blob does not exist.)
 ErrorCode: BlobNotFound
Content:
<?xml version="1.0" encoding="utf-8"?><Error><Code>BlobNotFound</Code><Message>The specified blob does not exist.
</Message></Error>

下面是我的 Startup.cs 文件：

[assembly: FunctionsStartup(typeof(Startup))]
namespace Emails.Dispatcher
{
    public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            builder.Services.AddSingleton(x =>
            new BlobServiceClient(connectionString: Environment.GetEnvironmentVariable("AzureWebJobsStorage")));

            builder.Services.AddSingleton<IBlobService, BlobService>();

            builder.Services.AddLogging();
            builder.Services.AddHttpClient();
            builder.AddHelpers();
            builder.Services.AddWorkers();

        }
    }
}

Blob 服务：

public class BlobService : IBlobService
{
    private readonly BlobServiceClient _blobServiceClient;

    public BlobService(BlobServiceClient blobServiceClient)
    {
        this._blobServiceClient = blobServiceClient;
    }

    public async Task<byte[]> DownloadAsync(string containerName, string fileUri)
    {
        var containerClient = _blobServiceClient.GetBlobContainerClient(containerName);

        var blobClient = containerClient.GetBlobClient(fileUri);

        using (var ms = new MemoryStream())
        {
            await blobClient.DownloadStreamingAsync();
            return ms.ToArray();
        }
    }

    public async Task<BlobDto> UploadAsync(string containerName, string filename, string content)
    {
        var containerClient = _blobServiceClient.GetBlobContainerClient(containerName);

        var blobClient = containerClient.GetBlobClient(filename);

        var bytes = Encoding.UTF8.GetBytes(content);

        await using var memoryStream = new MemoryStream(bytes);

        await blobClient.UploadAsync(content);

        return new BlobDto
        {
            Uri = blobClient.Uri,
            Name = blobClient.Name
        };
    }
}

public interface IBlobService
{
    Task<BlobDto> UploadAsync(string containerName, string filename, string content);

    Task<byte[]> DownloadAsync(string containerName, string fileUri);
}

实际上此服务正在接收完整的 blob url （即 https://{storage-url}.blob.core.windows.net/{container-name}/files/unzip/691ec307-7c2b-4aaa-8f75-8742c9faa9f5/ 1615015726/{文件名}.pdf).

我在这里错过了什么吗？

Answer 1

我可以借助 CloudBlockBlob 的 Uri 和 Name 属性来下载 blob 文件。如下图：

  public async Task<byte[]> DownloadAsync(string containerName, string fileUri)
        {
            var containerClient = _blobServiceClient.GetBlobContainerClient(containerName);

            var blobUri = new System.Uri(fileUri);

            var name = new CloudBlockBlob(blobUri).Name;

            var blobClient = containerClient.GetBlobClient(name);

            var response = await blobClient.DownloadStreamingAsync();

            using MemoryStream ms = new MemoryStream();

            await response.Value.Content.CopyToAsync(ms);

            ms.Position = 0;

            return ms.ToArray();
        }

Answer 2

问题出在以下代码行：

var blobClient = containerClient.GetBlobClient(fileUri);

使用

BlobClient

和 ContainerClient

 创建 

GetBlobClient 时，您只需提供 blob 的名称，而不是整个 URL。

要解决此问题，只需传递 blob 名称即可。

Answer 3

您的 blob 名称中可能有未分配的字符串。

有效的解决方法：将段号替换为文件容器段号，并使用替换来修复未知的文件名字符。

CloudBlobDirectory dira = Container.GetDirectoryReference(string.Empty);

var rootDirFolders = dira.ListBlobsSegmentedAsync(true, BlobListingDetails.Metadata, null, null, null, null).Result.Results;

foreach（rootDirFolders 中的 var blob）

{

var blockBlob = Container.GetBlockBlobReference(blob.StorageUri.PrimaryUri.Segments[2].Replace("%20", " "));

          



var blockBlobRecent = blockBlob.Name.Contains(formatdateValue); //filters blobs by date. Standard practice is that each blob has date in the name. Avoid using Modified date as filter

if (blockBlobRecent)

{

    string localPath = DownloadPath + blob.StorageUri.PrimaryUri.Segments[2].Replace("%20", " ");

    string localPathfinal = localPath.Replace("%20", " ");

    await blockBlob.DownloadToFileAsync(localPathfinal, FileMode.Create).ConfigureAwait(false);

}

else

{

    //do nothing

}

}