使用 .NET 版本 11.x 客户端库的 Azure Blob 存储代码示例

2023-04-03

本文演示了使用适用于 .NET 的 Azure Blob 存储客户端库版本 11.x 的代码示例。

2023 年 3 月 31 日，我们停用了对不符合当前 Azure SDK 指南的 Azure SDK 库的支持。新的 Azure SDK 库会定期更新，以推动一致的体验并增强安全态势。建议转换到新的 Azure SDK 库，以利用新功能和关键安全更新。

尽管 2023 年 3 月 31 日之后仍然可以使用较旧的库，但它们将不再从 Microsoft 获得官方支持和更新。有关详细信息，请参阅支持停用公告。

创建快照

若要使用适用于 .NET 的 Azure 存储客户端库版本 11.x 创建块 Blob 的快照，请使用以下方法之一：

下面的代码示例演示如何使用版本 11.x 创建快照。此示例指定在创建快照时添加的额外元数据。

private static async Task CreateBlockBlobSnapshot(CloudBlobContainer container)
{
    // Create a new block blob in the container.
    CloudBlockBlob baseBlob = container.GetBlockBlobReference("sample-base-blob.txt");

    // Add blob metadata.
    baseBlob.Metadata.Add("ApproxBlobCreatedDate", DateTime.UtcNow.ToString());

    try
    {
        // Upload the blob to create it, with its metadata.
        await baseBlob.UploadTextAsync(string.Format("Base blob: {0}", baseBlob.Uri.ToString()));

        // Sleep 5 seconds.
        System.Threading.Thread.Sleep(5000);

        // Create a snapshot of the base blob.
        // You can specify metadata at the time that the snapshot is created.
        // If no metadata is specified, then the blob's metadata is copied to the snapshot.
        Dictionary<string, string> metadata = new Dictionary<string, string>();
        metadata.Add("ApproxSnapshotCreatedDate", DateTime.UtcNow.ToString());
        await baseBlob.CreateSnapshotAsync(metadata, null, null, null);
        Console.WriteLine(snapshot.SnapshotQualifiedStorageUri.PrimaryUri);
    }
    catch (StorageException e)
    {
        Console.WriteLine(e.Message);
        Console.ReadLine();
        throw;
    }
}

删除快照

若要使用适用于 .NET 的 Azure 存储客户端库版本 11.x 删除 Blob 及其快照，请使用以下 blob 删除方法之一，并包括 DeleteSnapshotsOption 枚举：

下面的代码示例演示如何在 .NET 中删除 blob 及其快照，其中 blockBlob 是 [CloudBlockBlob][dotnet_CloudBlockBlob] 类型的对象：

await blockBlob.DeleteIfExistsAsync(DeleteSnapshotsOption.IncludeSnapshots, null, null, null);

创建存储访问策略

若要在具有适用于 Azure 存储的 .NET 客户端库版本 11.x 的容器上创建存储访问策略，请调用以下方法之一：

以下示例创建一个存储的访问策略，该策略在一天内生效，并授予读取、写入和列表权限：

private static async Task CreateStoredAccessPolicyAsync(CloudBlobContainer container, string policyName)
{
    // Create a new stored access policy and define its constraints.
    // The access policy provides create, write, read, list, and delete permissions.
    SharedAccessBlobPolicy sharedPolicy = new SharedAccessBlobPolicy()
    {
        // When the start time for the SAS is omitted, the start time is assumed to be the time when Azure Storage receives the request.
        SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
        Permissions = SharedAccessBlobPermissions.Read | SharedAccessBlobPermissions.List |
            SharedAccessBlobPermissions.Write
    };

    // Get the container's existing permissions.
    BlobContainerPermissions permissions = await container.GetPermissionsAsync();

    // Add the new policy to the container's permissions, and set the container's permissions.
    permissions.SharedAccessPolicies.Add(policyName, sharedPolicy);
    await container.SetPermissionsAsync(permissions);
}

为 blob 容器创建服务 SAS

若要为容器创建服务 SAS，请调用 CloudBlobContainer.GetSharedAccessSignature 方法。

private static string GetContainerSasUri(CloudBlobContainer container,
                                         string storedPolicyName = null)
{
    string sasContainerToken;

    // If no stored policy is specified, create a new access policy and define its constraints.
    if (storedPolicyName == null)
    {
        // Note that the SharedAccessBlobPolicy class is used both to define
        // the parameters of an ad hoc SAS, and to construct a shared access policy
        // that is saved to the container's shared access policies.
        SharedAccessBlobPolicy adHocPolicy = new SharedAccessBlobPolicy()
        {
            // When the start time for the SAS is omitted, the start time is assumed
            // to be the time when the storage service receives the request. Omitting
            // the start time for a SAS that is effective immediately helps to avoid clock skew.
            SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
            Permissions = SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.List
        };

        // Generate the shared access signature on the container,
        // setting the constraints directly on the signature.
        sasContainerToken = container.GetSharedAccessSignature(adHocPolicy, null);

        Console.WriteLine("SAS for blob container (ad hoc): {0}", sasContainerToken);
        Console.WriteLine();
    }
    else
    {
        // Generate the shared access signature on the container. In this case,
        // all of the constraints for the shared access signature are specified
        // on the stored access policy, which is provided by name. It is also possible
        // to specify some constraints on an ad hoc SAS and others on the stored access policy.
        sasContainerToken = container.GetSharedAccessSignature(null, storedPolicyName);

        Console.WriteLine("SAS for container (stored access policy): {0}", sasContainerToken);
        Console.WriteLine();
    }

    // Return the URI string for the container, including the SAS token.
    return container.Uri + sasContainerToken;
}

为 blob 创建服务 SAS

若要为 Blob 创建服务 SAS，请调用 CloudBlob.GetSharedAccessSignature 方法。

private static string GetBlobSasUri(CloudBlobContainer container,
                                    string blobName,
                                    string policyName = null)
{
    string sasBlobToken;

    // Get a reference to a blob within the container.
    // Note that the blob may not exist yet, but a SAS can still be created for it.
    CloudBlockBlob blob = container.GetBlockBlobReference(blobName);

    if (policyName == null)
    {
        // Create a new access policy and define its constraints.
        // Note that the SharedAccessBlobPolicy class is used both to define the parameters
        // of an ad hoc SAS, and to construct a shared access policy that is saved to
        // the container's shared access policies.
        SharedAccessBlobPolicy adHocSAS = new SharedAccessBlobPolicy()
        {
            // When the start time for the SAS is omitted, the start time is assumed to be
            // the time when the storage service receives the request. Omitting the start time
            // for a SAS that is effective immediately helps to avoid clock skew.
            SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
            Permissions = SharedAccessBlobPermissions.Read |
                          SharedAccessBlobPermissions.Write |
                          SharedAccessBlobPermissions.Create
        };

        // Generate the shared access signature on the blob,
        // setting the constraints directly on the signature.
        sasBlobToken = blob.GetSharedAccessSignature(adHocSAS);

        Console.WriteLine("SAS for blob (ad hoc): {0}", sasBlobToken);
        Console.WriteLine();
    }
    else
    {
        // Generate the shared access signature on the blob. In this case, all of the constraints
        // for the SAS are specified on the container's stored access policy.
        sasBlobToken = blob.GetSharedAccessSignature(null, policyName);

        Console.WriteLine("SAS for blob (stored access policy): {0}", sasBlobToken);
        Console.WriteLine();
    }

    // Return the URI string for the container, including the SAS token.
    return blob.Uri + sasBlobToken;
}

创建帐户 SAS

若要为容器创建帐户 SAS，请调用 CloudStorageAccount.GetSharedAccessSignature 方法。

下面的代码示例创建一个对 Blob 和文件服务有效的帐户 SAS，并授予客户端访问服务级别 API 的读取、写入和列表权限。帐户 SAS 将协议限制为 HTTPS，因此必须使用 HTTPS 发出请求。请务必将尖括号中的占位符值替换为你自己的值：

static string GetAccountSASToken()
{
    // To create the account SAS, you need to use Shared Key credentials. Modify for your account.
    const string ConnectionString = "DefaultEndpointsProtocol=https;AccountName=<storage-account>;AccountKey=<account-key>";
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConnectionString);

    // Create a new access policy for the account.
    SharedAccessAccountPolicy policy = new SharedAccessAccountPolicy()
        {
            Permissions = SharedAccessAccountPermissions.Read | 
                          SharedAccessAccountPermissions.Write | 
                          SharedAccessAccountPermissions.List,
            Services = SharedAccessAccountServices.Blob | SharedAccessAccountServices.File,
            ResourceTypes = SharedAccessAccountResourceTypes.Service,
            SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
            Protocols = SharedAccessProtocol.HttpsOnly
        };

    // Return the SAS token.
    return storageAccount.GetSharedAccessSignature(policy);
}

使用来自客户端生成的帐户 SAS

在此代码片段中，将 <storage-account> 占位符替换为存储帐户的名称。

static void UseAccountSAS(string sasToken)
{
    // Create new storage credentials using the SAS token.
    StorageCredentials accountSAS = new StorageCredentials(sasToken);
    // Use these credentials and the account name to create a Blob service client.
    CloudStorageAccount accountWithSAS = new CloudStorageAccount(accountSAS, "<storage-account>", endpointSuffix: null, useHttps: true);
    CloudBlobClient blobClientWithSAS = accountWithSAS.CreateCloudBlobClient();

    // Now set the service properties for the Blob client created with the SAS.
    blobClientWithSAS.SetServiceProperties(new ServiceProperties()
    {
        HourMetrics = new MetricsProperties()
        {
            MetricsLevel = MetricsLevel.ServiceAndApi,
            RetentionDays = 7,
            Version = "1.0"
        },
        MinuteMetrics = new MetricsProperties()
        {
            MetricsLevel = MetricsLevel.ServiceAndApi,
            RetentionDays = 7,
            Version = "1.0"
        },
        Logging = new LoggingProperties()
        {
            LoggingOperations = LoggingOperations.All,
            RetentionDays = 14,
            Version = "1.0"
        }
    });

    // The permissions granted by the account SAS also permit you to retrieve service properties.
    ServiceProperties serviceProperties = blobClientWithSAS.GetServiceProperties();
    Console.WriteLine(serviceProperties.HourMetrics.MetricsLevel);
    Console.WriteLine(serviceProperties.HourMetrics.RetentionDays);
    Console.WriteLine(serviceProperties.HourMetrics.Version);
}

Blob 的乐观并发控制

代码示例：

public void DemonstrateOptimisticConcurrencyBlob(string containerName, string blobName)
{
    Console.WriteLine("Demonstrate optimistic concurrency");

    // Parse connection string and create container.
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConnectionString);
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
    CloudBlobContainer container = blobClient.GetContainerReference(containerName);
    container.CreateIfNotExists();

    // Create test blob. The default strategy is last writer wins, so
    // write operation will overwrite existing blob if present.
    CloudBlockBlob blockBlob = container.GetBlockBlobReference(blobName);
    blockBlob.UploadText("Hello World!");

    // Retrieve the ETag from the newly created blob.
    string originalETag = blockBlob.Properties.ETag;
    Console.WriteLine("Blob added. Original ETag = {0}", originalETag);

    /// This code simulates an update by another client.
    string helloText = "Blob updated by another client.";
    // No ETag was provided, so original blob is overwritten and ETag updated.
    blockBlob.UploadText(helloText);
    Console.WriteLine("Blob updated. Updated ETag = {0}", blockBlob.Properties.ETag);

    // Now try to update the blob using the original ETag value.
    try
    {
        Console.WriteLine(@"Attempt to update blob using original ETag
                            to generate if-match access condition");
        blockBlob.UploadText(helloText, accessCondition: AccessCondition.GenerateIfMatchCondition(originalETag));
    }
    catch (StorageException ex)
    {
        if (ex.RequestInformation.HttpStatusCode == (int)HttpStatusCode.PreconditionFailed)
        {
            Console.WriteLine(@"Precondition failure as expected.
                                Blob's ETag does not match.");
        }
        else
        {
            throw;
        }
    }
    Console.WriteLine();
}

Blob 的悲观并发

代码示例：

public void DemonstratePessimisticConcurrencyBlob(string containerName, string blobName)
{
    Console.WriteLine("Demonstrate pessimistic concurrency");

    // Parse connection string and create container.
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConnectionString);
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
    CloudBlobContainer container = blobClient.GetContainerReference(containerName);
    container.CreateIfNotExists();

    CloudBlockBlob blockBlob = container.GetBlockBlobReference(blobName);
    blockBlob.UploadText("Hello World!");
    Console.WriteLine("Blob added.");

    // Acquire lease for 15 seconds.
    string lease = blockBlob.AcquireLease(TimeSpan.FromSeconds(15), null);
    Console.WriteLine("Blob lease acquired. Lease = {0}", lease);

    // Update blob using lease. This operation should succeed.
    const string helloText = "Blob updated";
    var accessCondition = AccessCondition.GenerateLeaseCondition(lease);
    blockBlob.UploadText(helloText, accessCondition: accessCondition);
    Console.WriteLine("Blob updated using an exclusive lease");

    // Simulate another client attempting to update to blob without providing lease.
    try
    {
        // Operation will fail as no valid lease was provided.
        Console.WriteLine("Now try to update blob without valid lease.");
        blockBlob.UploadText("Update operation will fail without lease.");
    }
    catch (StorageException ex)
    {
        if (ex.RequestInformation.HttpStatusCode == (int)HttpStatusCode.PreconditionFailed)
        {
            Console.WriteLine(@"Precondition failure error as expected.
                                Blob lease not provided.");
        }
        else
        {
            throw;
        }
    }

    // Release lease proactively.
    blockBlob.ReleaseLease(accessCondition);
    Console.WriteLine();
}

使用 Blob 存储生成高度可用的应用

下载示例项目，解压缩 storage-dotnet-circuit-breaker-pattern-ha-apps-using-ra-grs.zip 文件，然后导航到 v11 文件夹以查找项目文件。

还可以使用 git 将应用程序的副本下载到开发环境。 v11 文件夹中的示例项目包含控制台应用程序。

git clone https://github.com/Azure-Samples/storage-dotnet-circuit-breaker-pattern-ha-apps-using-ra-grs.git

配置样本

在应用程序中，必须为存储帐户提供连接字符串。可以将此连接字符串存储在运行应用程序的本地计算机上的环境变量中。请根据您的操作系统选择以下示例之一来创建环境变量。

在 Azure 门户中导航到存储帐户。在存储帐户的“设置” 下选择“访问密钥” 。从主密钥或辅助密钥复制连接字符串。根据你的操作系统，运行以下命令之一，并将 <你的连接字符串> 替换为实际的连接字符串。此命令将环境变量保存到本地计算机。在 Windows 中，在重新加载 命令提示符 或 shell 之前，环境变量不可用。

运行控制台应用程序

在 Visual Studio 中，按 F5 或选择“启动”，开始调试应用程序。如果配置了包还原，Visual Studio 会自动还原缺少的 NuGet 包，请访问安装并重新安装包并还原包以了解详细信息。

控制台窗口随即启动，应用程序开始运行。应用程序将解决方案中的 HelloWorld.png 映像上传到存储帐户。应用程序会检查以验证映像是否已复制到辅助 RA-GZRS 终结点。然后，它开始下载映像最多 999 次。每个读取都由 P 或 S表示。其中 P 表示主终结点，S 表示辅助终结点。

在示例代码中，RunCircuitBreakerAsync任务在Program.cs文件中用于使用DownloadToFileAsync方法从存储帐户下载图像。在下载之前，将定义 OperationContext 。操作上下文定义了事件处理程序，这些程序在下载成功完成时触发，或在下载失败并正在重试时触发。

了解示例代码

重试事件处理程序

下载映像失败并设置为重试时，将调用 OperationContextRetrying 事件处理程序。如果达到了应用程序中定义的最大重试次数，则请求的 LocationMode 更改为 SecondaryOnly。此设置强制应用程序尝试从辅助终结点下载映像。此配置减少了请求映像所需的时间，因为主终结点不会无限期重试。

private static void OperationContextRetrying(object sender, RequestEventArgs e)
{
    retryCount++;
    Console.WriteLine("Retrying event because of failure reading the primary. RetryCount = " + retryCount);

    // Check if we have had more than n retries in which case switch to secondary.
    if (retryCount >= retryThreshold)
    {

        // Check to see if we can fail over to secondary.
        if (blobClient.DefaultRequestOptions.LocationMode != LocationMode.SecondaryOnly)
        {
            blobClient.DefaultRequestOptions.LocationMode = LocationMode.SecondaryOnly;
            retryCount = 0;
        }
        else
        {
            throw new ApplicationException("Both primary and secondary are unreachable. Check your application's network connection. ");
        }
    }
}

请求已完成的事件处理程序

成功下载映像时，将调用 OperationContextRequestCompleted 事件处理程序。如果应用程序正在使用辅助终结点，应用程序将继续使用此终结点最多 20 次。 20 次后，应用程序将 LocationMode 设置为 PrimaryThenSecondary 并重试主终结点。如果请求成功，应用程序将继续从主终结点读取。

private static void OperationContextRequestCompleted(object sender, RequestEventArgs e)
{
    if (blobClient.DefaultRequestOptions.LocationMode == LocationMode.SecondaryOnly)
    {
        // You're reading the secondary. Let it read the secondary [secondaryThreshold] times,
        //    then switch back to the primary and see if it's available now.
        secondaryReadCount++;
        if (secondaryReadCount >= secondaryThreshold)
        {
            blobClient.DefaultRequestOptions.LocationMode = LocationMode.PrimaryThenSecondary;
            secondaryReadCount = 0;
        }
    }
}

将大量随机数据上传到 Azure 存储

最小和最大线程数设置为 100，以确保允许大量的并发连接。

private static async Task UploadFilesAsync()
{
    // Create five randomly named containers to store the uploaded files.
    CloudBlobContainer[] containers = await GetRandomContainersAsync();

    var currentdir = System.IO.Directory.GetCurrentDirectory();

    // Path to the directory to upload
    string uploadPath = currentdir + "\\upload";

    // Start a timer to measure how long it takes to upload all the files.
    Stopwatch time = Stopwatch.StartNew();

    try
    {
        Console.WriteLine("Iterating in directory: {0}", uploadPath);

        int count = 0;
        int max_outstanding = 100;
        int completed_count = 0;

        // Define the BlobRequestOptions on the upload.
        // This includes defining an exponential retry policy to ensure that failed connections
        // are retried with a back off policy. As multiple large files are being uploaded using
        // large block sizes, this can cause an issue if an exponential retry policy is not defined.
        // Additionally, parallel operations are enabled with a thread count of 8.
        // This should be a multiple of the number of processor cores in the machine.
        // Lastly, MD5 hash validation is disabled for this example, improving the upload speed.
        BlobRequestOptions options = new BlobRequestOptions
        {
            ParallelOperationThreadCount = 8,
            DisableContentMD5Validation = true,
            StoreBlobContentMD5 = false
        };

        // Create a new instance of the SemaphoreSlim class to 
        // define the number of threads to use in the application.
        SemaphoreSlim sem = new SemaphoreSlim(max_outstanding, max_outstanding);

        List<Task> tasks = new List<Task>();
        Console.WriteLine("Found {0} file(s)", Directory.GetFiles(uploadPath).Count());

        // Iterate through the files
        foreach (string path in Directory.GetFiles(uploadPath))
        {
            var container = containers[count % 5];
            string fileName = Path.GetFileName(path);
            Console.WriteLine("Uploading {0} to container {1}", path, container.Name);
            CloudBlockBlob blockBlob = container.GetBlockBlobReference(fileName);

            // Set the block size to 100MB.
            blockBlob.StreamWriteSizeInBytes = 100 * 1024 * 1024;

            await sem.WaitAsync();

            // Create a task for each file to upload. The tasks are
            // added to a collection and all run asynchronously.
            tasks.Add(blockBlob.UploadFromFileAsync(path, null, options, null).ContinueWith((t) =>
            {
                sem.Release();
                Interlocked.Increment(ref completed_count);
            }));

            count++;
        }

        // Run all the tasks asynchronously.
        await Task.WhenAll(tasks);

        time.Stop();

        Console.WriteLine("Upload has been completed in {0} seconds. Press any key to continue", time.Elapsed.TotalSeconds.ToString());

        Console.ReadLine();
    }
    catch (DirectoryNotFoundException ex)
    {
        Console.WriteLine("Error parsing files in the directory: {0}", ex.Message);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
}

除了设置线程和连接限制设置外，UploadFromStreamAsync 方法的 BlobRequestOptions 配置为使用并行度并禁用 MD5 哈希验证。这些文件以100兆字节块形式上传，此配置可以提高性能，但在网络状况不佳的情况下可能代价昂贵，因为如果失败，整个100兆字节块都会被重试。

财产	价值	DESCRIPTION
并行操作线程数	8	该设置在上传时将 Blob 分解为块。为了获得最佳性能，此值应是核心数的八倍。
禁用ContentMD5验证	是	此属性禁用检查上传的内容的 MD5 哈希。禁用 MD5 验证会产生更快的传输。但不确认正在传输的文件的有效性或完整性。
StoreBlobContentMD5	假	此属性决定是否计算 MD5 哈希，并将其与文件一起存储。
RetryPolicy	2 秒回退，最大重试次数为 10	确定请求的重试策略。若连接失败会进行重试，在此示例中，配置了指数重试策略，回退时间为2秒，最大重试次数为10次。当应用程序接近达到 Blob 存储的可伸缩性目标时，此设置非常重要。有关详细信息，请参阅 Blob 存储可伸缩性和性能目标。

从 Azure 存储下载大量随机数据

应用程序读取存储在 storageconnectionstring 中指定的存储帐户中的容器。它一次使用容器中的 ListBlobsSegmentedAsync 方法循环访问 blob 10，并使用 DownloadToFileAsync 方法将其下载到本地计算机。

下表显示了下载每个 Blob 时定义的 BlobRequestOptions。

财产	价值	DESCRIPTION
禁用内容MD5验证	是	此属性禁用检查上传的内容的 MD5 哈希。禁用 MD5 验证会产生更快的传输。但不确认正在传输的文件的有效性或完整性。
StoreBlobContentMD5	假	此属性确定是否计算并存储 MD5 哈希。

private static async Task DownloadFilesAsync()
{
    CloudBlobClient blobClient = GetCloudBlobClient();

    // Define the BlobRequestOptions on the download, including disabling MD5 
    // hash validation for this example, this improves the download speed.
    BlobRequestOptions options = new BlobRequestOptions
    {
        DisableContentMD5Validation = true,
        StoreBlobContentMD5 = false
    };

    // Retrieve the list of containers in the storage account.
    // Create a directory and configure variables for use later.
    BlobContinuationToken continuationToken = null;
    List<CloudBlobContainer> containers = new List<CloudBlobContainer>();
    do
    {
        var listingResult = await blobClient.ListContainersSegmentedAsync(continuationToken);
        continuationToken = listingResult.ContinuationToken;
        containers.AddRange(listingResult.Results);
    }
    while (continuationToken != null);

    var directory = Directory.CreateDirectory("download");
    BlobResultSegment resultSegment = null;
    Stopwatch time = Stopwatch.StartNew();

    // Download the blobs
    try
    {
        List<Task> tasks = new List<Task>();
        int max_outstanding = 100;
        int completed_count = 0;

        // Create a new instance of the SemaphoreSlim class to
        // define the number of threads to use in the application.
        SemaphoreSlim sem = new SemaphoreSlim(max_outstanding, max_outstanding);

        // Iterate through the containers
        foreach (CloudBlobContainer container in containers)
        {
            do
            {
                // Return the blobs from the container, 10 at a time.
                resultSegment = await container.ListBlobsSegmentedAsync(null, true, BlobListingDetails.All, 10, continuationToken, null, null);
                continuationToken = resultSegment.ContinuationToken;
                {
                    foreach (var blobItem in resultSegment.Results)
                    {

                        if (((CloudBlob)blobItem).Properties.BlobType == BlobType.BlockBlob)
                        {
                            // Get the blob and add a task to download the blob asynchronously from the storage account.
                            CloudBlockBlob blockBlob = container.GetBlockBlobReference(((CloudBlockBlob)blobItem).Name);
                            Console.WriteLine("Downloading {0} from container {1}", blockBlob.Name, container.Name);
                            await sem.WaitAsync();
                            tasks.Add(blockBlob.DownloadToFileAsync(directory.FullName + "\\" + blockBlob.Name, FileMode.Create, null, options, null).ContinueWith((t) =>
                            {
                                sem.Release();
                                Interlocked.Increment(ref completed_count);
                            }));

                        }
                    }
                }
            }
            while (continuationToken != null);
        }

        // Creates an asynchronous task that completes when all the downloads complete.
        await Task.WhenAll(tasks);
    }
    catch (Exception e)
    {
        Console.WriteLine("\nError encountered during transfer: {0}", e.Message);
    }

    time.Stop();
    Console.WriteLine("Download has been completed in {0} seconds. Press any key to continue", time.Elapsed.TotalSeconds.ToString());
    Console.ReadLine();
}

启用 Azure 存储分析日志（经典）

代码示例：

var storageAccount = CloudStorageAccount.Parse(connStr);  
var queueClient = storageAccount.CreateCloudQueueClient();  
var serviceProperties = queueClient.GetServiceProperties();

serviceProperties.Logging.LoggingOperations = LoggingOperations.All;  
serviceProperties.Logging.RetentionDays = 2;

queueClient.SetServiceProperties(serviceProperties);

修改日志数据保留期

下面的示例将 blob 和队列存储服务的保留期输出到控制台。

var storageAccount = CloudStorageAccount.Parse(connectionString);

var blobClient = storageAccount.CreateCloudBlobClient();
var queueClient = storageAccount.CreateCloudQueueClient();

var blobserviceProperties = blobClient.GetServiceProperties();
var queueserviceProperties = queueClient.GetServiceProperties();

Console.WriteLine("Retention period for logs from the blob service is: " +
   blobserviceProperties.Logging.RetentionDays.ToString());

Console.WriteLine("Retention period for logs from the queue service is: " +
   queueserviceProperties.Logging.RetentionDays.ToString());

以下示例将 blob 和队列存储服务的日志保留期更改为 4 天。


blobserviceProperties.Logging.RetentionDays = 4;
queueserviceProperties.Logging.RetentionDays = 4;

blobClient.SetServiceProperties(blobserviceProperties);
queueClient.SetServiceProperties(queueserviceProperties);

启用 Azure 存储分析指标（经典）

代码示例：

var storageAccount = CloudStorageAccount.Parse(connStr);  
var queueClient = storageAccount.CreateCloudQueueClient();  
var serviceProperties = queueClient.GetServiceProperties();

serviceProperties.HourMetrics.MetricsLevel = MetricsLevel.Service;  
serviceProperties.HourMetrics.RetentionDays = 10;

queueClient.SetServiceProperties(serviceProperties);

为客户端应用程序配置传输层安全性（TLS）

以下示例演示如何使用 Azure 存储客户端库版本 11.x 在 .NET 客户端中启用 TLS 1.2：

static void EnableTls12()
{
    // Enable TLS 1.2 before connecting to Azure Storage
    System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

    // Add your connection string here.
    string connectionString = "";

    // Connect to Azure Storage and create a new container.
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connectionString);
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

    CloudBlobContainer container = blobClient.GetContainerReference("sample-container");
    container.CreateIfNotExists();
}

监控、诊断和解决 Microsoft Azure 存储（经典）问题

如果存储客户端库在客户端中引发 StorageException，那么 RequestInformation 属性包含一个 RequestResult 对象，该对象包括一个 ServiceRequestID 属性。还可以从 OperationContext 实例访问 RequestResult 对象。

下面的代码示例演示如何通过将 OperationContext 对象附加到存储服务来设置自定义 ClientRequestId 值。它还演示如何从响应消息中检索 ServerRequestId 值。

//Parse the connection string for the storage account.
const string ConnectionString = "DefaultEndpointsProtocol=https;AccountName=account-name;AccountKey=account-key";
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConnectionString);
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

// Create an Operation Context that includes custom ClientRequestId string based on constants defined within the application along with a Guid.
OperationContext oc = new OperationContext();
oc.ClientRequestID = String.Format("{0} {1} {2} {3}", HOSTNAME, APPNAME, USERID, Guid.NewGuid().ToString());

try
{
    CloudBlobContainer container = blobClient.GetContainerReference("democontainer");
    ICloudBlob blob = container.GetBlobReferenceFromServer("testImage.jpg", null, null, oc);  
    var downloadToPath = string.Format("./{0}", blob.Name);
    using (var fs = File.OpenWrite(downloadToPath))
    {
        blob.DownloadToStream(fs, null, null, oc);
        Console.WriteLine("\t Blob downloaded to file: {0}", downloadToPath);
    }
}
catch (StorageException storageException)
{
    Console.WriteLine("Storage exception {0} occurred", storageException.Message);
    // Multiple results may exist due to client side retry logic - each retried operation will have a unique ServiceRequestId
    foreach (var result in oc.RequestResults)
    {
            Console.WriteLine("HttpStatus: {0}, ServiceRequestId {1}", result.HttpStatusCode, result.ServiceRequestID);
    }
}

调查客户端性能问题 - 禁用 Nagle 算法

代码示例：

var storageAccount = CloudStorageAccount.Parse(connStr);
ServicePoint queueServicePoint = ServicePointManager.FindServicePoint(storageAccount.QueueEndpoint);
queueServicePoint.UseNagleAlgorithm = false;

代码示例：

CloudBlobClient client = new CloudBlobClient(blobEndpoint, new StorageCredentials(accountName, accountKey));
// Set the service properties.
ServiceProperties sp = client.GetServiceProperties();
sp.DefaultServiceVersion = "2013-08-15";
CorsRule cr = new CorsRule();
cr.AllowedHeaders.Add("*");
cr.AllowedMethods = CorsHttpMethods.Get | CorsHttpMethods.Put;
cr.AllowedOrigins.Add("http://www.contoso.com");
cr.ExposedHeaders.Add("x-ms-*");
cr.MaxAgeInSeconds = 5;
sp.Cors.CorsRules.Clear();
sp.Cors.CorsRules.Add(cr);
client.SetServiceProperties(sp);

创建一个指定大小的空页 Blob

若要创建页 Blob，我们首先创建一个 CloudBlobClient 对象，其基本 URI 用于访问存储帐户（图 1 中的 pbaccount ）和 StorageCredentialsAccountAndKey 对象，如以下示例所示。然后，该示例演示如何创建对 CloudBlobContainer 对象的引用，然后创建容器（testvhds）（如果尚不存在）。然后使用 CloudBlobContainer 对象，通过指定要访问的页 Blob 名称（os4.vhd）来创建对 CloudPageBlob 对象的引用。若要创建页 blob，请调用 CloudPageBlob.Create，并传入要创建的 blob 的最大大小。 blobSize 必须是 512 字节的倍数。

using Microsoft.Azure;
using Microsoft.Azure.Storage;
using Microsoft.Azure.Storage.Blob;

long OneGigabyteAsBytes = 1024 * 1024 * 1024;
// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the blob client.
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

// Retrieve a reference to a container.
CloudBlobContainer container = blobClient.GetContainerReference("testvhds");

// Create the container if it doesn't already exist.
container.CreateIfNotExists();

CloudPageBlob pageBlob = container.GetPageBlobReference("os4.vhd");
pageBlob.Create(16 * OneGigabyteAsBytes);

将页 Blob 的大小调整

若要在创建后重设页 Blob 的大小，请使用 Resize 方法。请求的大小应为 512 字节的倍数。

pageBlob.Resize(32 * OneGigabyteAsBytes);

将页面写入页面 Blob

若要写入页面，请使用 CloudPageBlob.WritePages 方法。

pageBlob.WritePages(dataStream, startingOffset);

从页面 blob 中读取页内容

若要读取页面，请使用 CloudPageBlob.DownloadRangeToByteArray 方法从页 blob 读取一系列字节。

byte[] buffer = new byte[rangeSize];
pageBlob.DownloadRangeToByteArray(buffer, bufferOffset, pageBlobOffset, rangeSize);

若要确定哪些页面受数据支持，请使用 CloudPageBlob.GetPageRanges。然后，可以枚举返回的范围，并下载每个范围中的数据。

IEnumerable<PageRange> pageRanges = pageBlob.GetPageRanges();

foreach (PageRange range in pageRanges)
{
    // Calculate the range size
    int rangeSize = (int)(range.EndOffset + 1 - range.StartOffset);

    byte[] buffer = new byte[rangeSize];

    // Read from the correct starting offset in the page blob and
    // place the data in the bufferOffset of the buffer byte array
    pageBlob.DownloadRangeToByteArray(buffer, bufferOffset, range.StartOffset, rangeSize);

    // Then use the buffer for the page range just read
}

通过

使用 .NET 版本 11.x 客户端库的 Azure Blob 存储代码示例

创建快照

删除快照

创建存储访问策略

为 blob 容器创建服务 SAS

为 blob 创建服务 SAS

创建帐户 SAS

使用来自客户端生成的帐户 SAS

Blob 的乐观并发控制

Blob 的悲观并发

使用 Blob 存储生成高度可用的应用

配置样本

运行控制台应用程序

了解示例代码

重试事件处理程序

请求已完成的事件处理程序

将大量随机数据上传到 Azure 存储

从 Azure 存储下载大量随机数据

启用 Azure 存储分析日志（经典）

修改日志数据保留期

启用 Azure 存储分析指标（经典）

为客户端应用程序配置传输层安全性 （TLS）

监控、诊断和解决 Microsoft Azure 存储（经典）问题

调查客户端性能问题 - 禁用 Nagle 算法

调查网络延迟问题 - 配置跨源资源共享 （CORS）

创建一个指定大小的空页 Blob

将页 Blob 的大小调整

将页面写入页面 Blob

从页面 blob 中读取页内容

其他资源

为客户端应用程序配置传输层安全性（TLS）

调查网络延迟问题 - 配置跨源资源共享（CORS）