【Azure 存储服务】代码版 Azure Storage Blob 生成 SAS (Shared Access Signature: 共享访问签名)

问题描述

在使用Azure存储服务，为了有效的保护Storage的Access Keys。可以使用另一种授权方式访问资源(Shared Access Signature: 共享访问签名), 它的好处可以控制允许访问的IP，过期时间，权限 和 服务 等。Azure门户上提供了对Account级，Container级，Blob级的SAS生成服务。

那么使用代码如何来生成呢？

问题回答

以最常见的两种代码作为示例：.NET 和 Java

.NET

Blob SAS 将使用帐户访问密钥(Storage Account Key1 or Key2)进行签名。 使用 StorageSharedKeyCredential 类创建用于为 SAS 签名的凭据。 新建 BlobSasBuilder 对象，并调用 ToSasQueryParameters 以获取 SAS 令牌字符串。官方文档（https://docs.azure.cn/zh-cn/storage/blobs/sas-service-create?tabs=dotnet）中进行了详细介绍，直接使用以下部分代码即可生成Blob的SAS URL。

private static Uri GetServiceSasUriForBlob(BlobClient blobClient,
    string storedPolicyName = null)
{
    // Check whether this BlobClient object has been authorized with Shared Key.
    if (blobClient.CanGenerateSasUri)
    {
        // Create a SAS token that's valid for one hour.
        BlobSasBuilder sasBuilder = new BlobSasBuilder()
        {
            BlobContainerName = blobClient.GetParentBlobContainerClient().Name,
            BlobName = blobClient.Name,
            Resource = "b"
        };

        if (storedPolicyName == null)
        {
            sasBuilder.ExpiresOn = DateTimeOffset.UtcNow.AddHours(1);
            sasBuilder.SetPermissions(BlobSasPermissions.Read |
                BlobSasPermissions.Write);
        }
        else
        {
            sasBuilder.Identifier = storedPolicyName;
        }

        Uri sasUri = blobClient.GenerateSasUri(sasBuilder);
        Console.WriteLine("SAS URI for blob is: {0}", sasUri);
        Console.WriteLine();

        return sasUri;
    }
    else
    {
        Console.WriteLine(@"BlobClient must be authorized with Shared Key
                          credentials to create a service SAS.");
        return null;
    }
}

JAVA

而Java的示例代码在官网中并没有介绍，所以本文就Java生成SAS的代码进行讲解。

从Java新版的SDK（azure-storage-blob）中 ，可以发现 BlobServiceClient，BlobContainerClient ，BlobClient 对象中都包含 generateAccountSas 或 generateSas 方法来实现对Account， Container，Blob进行SAS Token生成，只需要根据它所需要的参数对

AccountSasSignatureValues 和 BlobServiceSasSignatureValues 初始化。 示例代码(全部代码可在文末下载)：

    public static void GenerateSASstring(BlobServiceClient blobServiceClient, BlobContainerClient blobContainerClient,
            BlobClient blobClient) {
        /*
         * Generate an account sas. Other samples in this file will demonstrate how to
         * create a client with the sas token.
         */
        // Configure the sas parameters. This is the minimal set.

        OffsetDateTime startTime = OffsetDateTime.now();
        OffsetDateTime expiryTime = OffsetDateTime.now().plusDays(1);
        AccountSasService services = new AccountSasService().setBlobAccess(true);
        AccountSasResourceType resourceTypes = new AccountSasResourceType().setObject(true);

        SasProtocol protocol = SasProtocol.HTTPS_ONLY;
        SasIpRange sasIpRange = SasIpRange.parse("167.220.255.73");

        // Generate the account sas.
        AccountSasPermission accountSasPermission = new AccountSasPermission().setReadPermission(true);
        AccountSasSignatureValues accountSasValues = new AccountSasSignatureValues(expiryTime, accountSasPermission,
                services, resourceTypes);
        accountSasValues.setStartTime(startTime);
        accountSasValues.setProtocol(protocol);
        accountSasValues.setSasIpRange(sasIpRange);

        String accountSasToken = blobServiceClient.generateAccountSas(accountSasValues);
        System.out.println("\nGenerate the account sas & url is :::: \n\t" + accountSasToken + "\n\t"
                + blobServiceClient.getAccountUrl() + "?" + accountSasToken);

        // Generate a sas using a container client
        BlobContainerSasPermission containerSasPermission = new BlobContainerSasPermission().setCreatePermission(true);
        BlobServiceSasSignatureValues serviceSasValues = new BlobServiceSasSignatureValues(expiryTime,
                containerSasPermission);
        serviceSasValues.setStartTime(startTime);
        serviceSasValues.setProtocol(protocol);
        serviceSasValues.setSasIpRange(sasIpRange);

        String containerSasToken = blobContainerClient.generateSas(serviceSasValues);
        System.out.println("\nGenerate the Container sas & url is :::: \n\t" + containerSasToken + "\n\t"
                + blobContainerClient.getBlobContainerUrl() + "?" + containerSasToken);

        // Generate a sas using a blob client
        BlobSasPermission blobSasPermission = new BlobSasPermission().setReadPermission(true);
        serviceSasValues = new BlobServiceSasSignatureValues(expiryTime, blobSasPermission);
        serviceSasValues.setStartTime(startTime);
        serviceSasValues.setProtocol(protocol);
        serviceSasValues.setSasIpRange(sasIpRange);

        String blobSasToken = blobClient.generateSas(serviceSasValues);
        System.out.println("\nGenerate the Blob sas & url is :::: \n\t" + blobSasToken + "\n\t"
                + blobClient.getBlobUrl() + "?" + blobSasToken);

    }

在pom.xml 中所需要加载的依赖项：

    <dependency>
      <groupId>com.azure</groupId>
      <artifactId>azure-storage-blob</artifactId>
      <version>12.13.0</version>
    </dependency>

以上代码中的各部分设置项 与 Azure门户上设置项的对应关系如下图：

运行效果图

附录一：Java Main函数全部代码：

package test;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URISyntaxException;
import java.security.InvalidKeyException;
import java.time.OffsetDateTime;
import java.util.Iterator;

import com.azure.storage.blob.BlobClient;
import com.azure.storage.blob.BlobContainerClient;
import com.azure.storage.blob.BlobServiceClient;
import com.azure.storage.blob.BlobServiceClientBuilder;
import com.azure.storage.blob.models.BlobItem;
import com.azure.storage.blob.sas.BlobContainerSasPermission;
import com.azure.storage.blob.sas.BlobSasPermission;
import com.azure.storage.blob.sas.BlobServiceSasSignatureValues;
import com.azure.storage.common.sas.AccountSasPermission;
import com.azure.storage.common.sas.AccountSasResourceType;
import com.azure.storage.common.sas.AccountSasService;
import com.azure.storage.common.sas.AccountSasSignatureValues;
import com.azure.storage.common.sas.SasIpRange;
import com.azure.storage.common.sas.SasProtocol;

/**
 * Hello world!
 *
 */
public class App {
    public static void main(String[] args)
            throws URISyntaxException, InvalidKeyException, RuntimeException, IOException {
        System.out.println("Hello World!");

        String storageConnectionString = "DefaultEndpointsProtocol=https;AccountName=<your storage account name>;AccountKey=**************************;EndpointSuffix=core.chinacloudapi.cn";
        String blobContainerName = "test";
        String dirName = "";

        // Create a BlobServiceClient object which will be used to create a container
        System.out.println("\nCreate a BlobServiceClient Object to Connect Storage Account");
        BlobServiceClient blobServiceClient = new BlobServiceClientBuilder().connectionString(storageConnectionString)
                .buildClient();

        // Create a unique name for the container
        String containerName = blobContainerName + java.util.UUID.randomUUID();

        // Create the container and return a container client object
        System.out.println("\nCreate new Container : " + containerName);
        BlobContainerClient containerClient = blobServiceClient.createBlobContainer(containerName);

        // Create a local file in the ./data/ directory for uploading and downloading

        System.out.println("\nCreate a local file in the ./data/ directory for uploading and downloading");
        String localPath = "./data/";
        String fileName = "quickstart" + java.util.UUID.randomUUID() + ".txt";
        File localFile = new File(localPath + fileName);
        // Write text to the file
        FileWriter writer = new FileWriter(localPath + fileName, true);
        writer.write("Hello, World! This is test file to download by SAS. Also test upload");
        writer.close();

        // Get a reference to a blob
        BlobClient blobClient = containerClient.getBlobClient(fileName);
        System.out.println("\nUploading to Blob storage as blob:\n\t" + blobClient.getBlobUrl());
        // Upload the blob
        blobClient.uploadFromFile(localPath + fileName);
        System.out.println("\nUpload blob completed : " + blobClient.getBlobName());

        System.out.println("\nListing blobs...");

        // List the blob(s) in the container.
        for (BlobItem blobItem : containerClient.listBlobs()) {
            System.out.println("\t" + blobItem.getName());
        }

        // Download the blob to a local file
        // Append the string "DOWNLOAD" before the .txt extension so that you can see
        // both files.
        String downloadFileName = fileName.replace(".txt", "DOWNLOAD.txt");
        File downloadedFile = new File(localPath + downloadFileName);

        System.out.println("\nDownloading blob to\n\t " + localPath + downloadFileName);

        blobClient.downloadToFile(localPath + downloadFileName);

        // Generate SAS String for blob user..
        System.out.println("\nGenerate SAS String for blob user..");
        GenerateSASstring(blobServiceClient, containerClient, blobClient);

        // Clean up
        System.out.println("\nPress the Enter word 'Delete' to begin clean up");
        boolean isDelete = System.console().readLine().toLowerCase().trim().equals("delete");

        if (isDelete) {
            System.out.println("Deleting blob container...");
            containerClient.delete();

            System.out.println("Deleting the local source and downloaded files...");
            localFile.delete();
            downloadedFile.delete();
        } else {
            System.out.println("Skip to Clean up operation");
        }

        System.out.println("Done");

    }

    public static void GenerateSASstring(BlobServiceClient blobServiceClient, BlobContainerClient blobContainerClient,
            BlobClient blobClient) {
        /*
         * Generate an account sas. Other samples in this file will demonstrate how to
         * create a client with the sas token.
         */
        // Configure the sas parameters. This is the minimal set.

        OffsetDateTime startTime = OffsetDateTime.now();
        OffsetDateTime expiryTime = OffsetDateTime.now().plusDays(1);
        AccountSasService services = new AccountSasService().setBlobAccess(true);
        AccountSasResourceType resourceTypes = new AccountSasResourceType().setObject(true);

        SasProtocol protocol = SasProtocol.HTTPS_ONLY;
        SasIpRange sasIpRange = SasIpRange.parse("167.220.255.73");

        // Generate the account sas.
        AccountSasPermission accountSasPermission = new AccountSasPermission().setReadPermission(true);
        AccountSasSignatureValues accountSasValues = new AccountSasSignatureValues(expiryTime, accountSasPermission,
                services, resourceTypes);
        accountSasValues.setStartTime(startTime);
        accountSasValues.setProtocol(protocol);
        accountSasValues.setSasIpRange(sasIpRange);

        String accountSasToken = blobServiceClient.generateAccountSas(accountSasValues);
        System.out.println("\nGenerate the account sas & url is :::: \n\t" + accountSasToken + "\n\t"
                + blobServiceClient.getAccountUrl() + "?" + accountSasToken);

        // Generate a sas using a container client
        BlobContainerSasPermission containerSasPermission = new BlobContainerSasPermission().setCreatePermission(true);
        BlobServiceSasSignatureValues serviceSasValues = new BlobServiceSasSignatureValues(expiryTime,
                containerSasPermission);
        serviceSasValues.setStartTime(startTime);
        serviceSasValues.setProtocol(protocol);
        serviceSasValues.setSasIpRange(sasIpRange);

        String containerSasToken = blobContainerClient.generateSas(serviceSasValues);
        System.out.println("\nGenerate the Container sas & url is :::: \n\t" + containerSasToken + "\n\t"
                + blobContainerClient.getBlobContainerUrl() + "?" + containerSasToken);

        // Generate a sas using a blob client
        BlobSasPermission blobSasPermission = new BlobSasPermission().setReadPermission(true);
        serviceSasValues = new BlobServiceSasSignatureValues(expiryTime, blobSasPermission);
        serviceSasValues.setStartTime(startTime);
        serviceSasValues.setProtocol(protocol);
        serviceSasValues.setSasIpRange(sasIpRange);

        String blobSasToken = blobClient.generateSas(serviceSasValues);
        System.out.println("\nGenerate the Blob sas & url is :::: \n\t" + blobSasToken + "\n\t"
                + blobClient.getBlobUrl() + "?" + blobSasToken);

    }

}

参考资料

快速入门：使用 Java v12 SDK 管理 blob：https://docs.azure.cn/zh-cn/storage/blobs/storage-quickstart-blobs-java

Azure Storage Blob client library for Java：https://github.com/Azure/azure-sdk-for-java/tree/main/sdk/storage/azure-storage-blob#generate-a-sas-token

示例下载：