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：demo.rar