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

项目
04/03/2023

本文介绍了使用适用于 .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

要使用 11.x 版用于 .NET 的 Azure 存储客户端库创建块 blob 快照，请使用以下任一方法：

以下代码示例演示如何在版本 11.x 中创建快照。该示例在创建快照时为其指定了额外的元数据。

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

要使用 11.x 版用于 .NET 的 Azure 存储客户端库删除 blob 及其快照，请使用以下任一 blob 删除方法，并包括 DeleteSnapshotsOption 枚举：

以下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

要使用适用于 Azure 存储的 .NET 客户端库版本 11.x 在容器上创建存储访问策略，请调用以下方法之一：

以下示例创建一个有效期为一天并授予读取、写入和列表权限的存储访问策略：

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。

以下代码示例创建一个帐户 SAS，该 SAS 对 Blob 和文件服务是有效的，并授予客户端读取、写入和列表权限，使其能够访问服务级别 API。帐户 SAS 将协议限制为 HTTPS，因此请求必须使用 HTTPS 发出。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);
}

通过客户端使用帐户 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

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 存储构建高可用性应用

下载示例项目，提取（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。

也可使用 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

配置示例

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的环境变量中。根据你的操作系统，按照下面的某个示例创建环境变量。

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。根据操作系统运行以下某个命令，将 <> 替换为实际连接字符串。此命令会将一个环境变量保存到本地计算机。在 Windows 中，必须重载正在使用的命令提示符或 shell，该环境变量才可用。

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 会自动还原丢失的 NuGet 包，请访问使用包还原安装和重新安装包，了解详细信息。

此时会启动一个控制台窗口，应用程序开始运行。应用程序将 HelloWorld.png 映像从解决方案上传到存储帐户。应用程序会进行检查，以确保映像已复制到辅助 RA-GZRS 终结点。然后，它开始下载映像，最多可下载 999 次。每次读取由 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，Program.cs 文件中的 RunCircuitBreakerAsync 任务用于通过 DownloadToFileAsync 方法下载存储帐户中的图像。下载前，将会先定义 OperationContext。操作上下文定义了在下载成功完成或下载失败并重试时触发的事件处理程序。

了解示例代码

Retry 事件处理程序

当映像下载失败并设置为重试时，将调用 OperationContextRetrying 事件处理程序。如果达到应用程序中定义的重试次数上限，请求的 LocationMode 会变为 SecondaryOnly。此设置强制应用程序从辅助终结点尝试下载该图像。此配置减少了请求获取映像所需的时间，因为不会无限重试主终结点。

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. ");
        }
    }
}

RequestCompleted 事件处理程序

当图像下载成功时，会调用 OperationContextRequestCompleted 事件处理程序。如果应用程序使用的是辅助终结点，则应用程序会继续使用该终结点，最多 20 次。 20 次以后，应用程序会将 LocationMode 重新设置为 PrimaryThenSecondary 并重试主终结点。如果请求成功，应用程序会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

最小线程数和最大线程数设置为 100，以确保允许大量并发连接。

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);
    }
}

除设置线程和连接限制设置外，还需将 UploadFromStreamAsync 方法的 BlobRequestOptions 配置为使用并行，并禁用 MD5 哈希验证。文件以 100 mb 的块上传，此配置提高了性能，但如果网络性能不佳，可能成本高昂，因为如果出现失败，会重试整个 100 mb 的块。

properties	值	说明
ParallelOperationThreadCount	8	上传时，此设置将 blob 分为多个块。为获得最佳性能，此值应为内核数的 8 倍。
DisableContentMD5Validation	true	该属性禁用对上传内容的 MD5 哈希检查。禁用 MD5 验证可加快传输速度。但是不能确认传输文件的有效性或完整性。
StoreBlobContentMD5	false	该属性确定是否计算和存储文件的 MD5 哈希。
RetryPolicy	2 秒回退，最多重试 10 次	确定请求的重试策略。重试连接失败，在此示例中，ExponentialRetry 策略配置为 2 秒回退，最多可重试 10 次。当应用程序快要达到 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 存储的可伸缩性和性能目标。

从 Azure 存储下载大量随机数据

应用程序读取位于 storageconnectionstring 中指定的存储帐户中的容器。它使用容器中的 ListBlobsSegmentedAsync 方法每次循环访问 10 个 Blob，并使用 DownloadToFileAsync 方法将它们下载到本地计算机。

下表显示了每个 Blob 下载完成后为其定义的 BlobRequestOptions。

属性	值	说明
DisableContentMD5Validation	true	该属性禁用对上传内容的 MD5 哈希检查。禁用 MD5 验证可加快传输速度。但是不能确认传输文件的有效性或完整性。
StoreBlobContentMD5	false	该属性确定是否计算和存储 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());

下面的示例将 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)

以下示例演示了如何使用 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();
}

监视和诊断 Microsoft Azure 存储并对其进行故障排除（经典）

如果存储客户端库在客户端上引发 StorageException，则 RequestInformation 属性将包含 RequestResult 对象（其中包含 ServiceRequestID 属性）。也可以通过 OperationContext 实例访问 RequestResult 对象。

下面的代码示例演示如何通过附加 OperationContext 对象（向存储服务发出的请求）设置自定义 ClientRequestId 值。它还演示了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);

创建指定大小的空页 Blob

为了创建页 Blob，让我们先创建一个 CloudBlobClient 对象，其中包含用于访问存储帐户（图 1 中的 pbaccount）的 Blob 存储的基 URI；另外创建 StorageCredentialsAccountAndKey 对象，如以下示例所示。然后，该示例展示了如何创建对 CloudBlobContainer 对象的引用，然后创建容器 (testvhds)（如果它尚未存在）。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);

重设页 Blob 的大小

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 Blob

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

pageBlob.WritePages(dataStream, startingOffset);

从页 Blob 中读取页面

若要读取页面，请使用 CloudPageBlob.DownloadRangeToByteArray 方法从页 Blob 中读取字节范围。

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

若要确定哪些页面以数据为基础，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

通过客户端使用帐户 SAS

Blob 的乐观并发

Blob 的悲观并发

使用 Blob 存储构建高可用性应用

配置示例

运行控制台应用程序

了解示例代码

Retry 事件处理程序

RequestCompleted 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)

监视和诊断 Microsoft Azure 存储并对其进行故障排除（经典）

调查客户端性能问题 - 禁用 Nagle 算法

调查网络延迟问题 - 配置跨域资源共享 (CORS)

创建指定大小的空页 Blob

重设页 Blob 的大小

将页面写入页 Blob

从页 Blob 中读取页面

其他资源