問題描述

通過.NET Azure Storage Blobs SDK , 獲取Blob的MD5值，查看了Azure操作手冊中，介紹可以使用 blob.Properties.ContentMD5 屬性。

    //blob 文件測試
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
    CloudBlobContainer container = blobClient.GetContainerReference("file");
    CloudBlockBlob blob = container.GetBlockBlobReference(@"image-03.jpg");
    blob.UploadFromFile(filePath1, FileMode.OpenOrCreate);
    Console.WriteLine("md5=" + blob.Properties.ContentMD5);

但是，在項目中，發(fā)現(xiàn)SDK更新后(Azure.Storage.Blobs 12.9.1)后，Properties中并沒有ContentMD5屬性？

image.png

問題解答

查看Blob Properties屬性的源代碼，發(fā)現(xiàn)沒有了ContentMD5, 但是可以使用ContentHash。如果把ContentHash進行Base64編碼后，它的結(jié)果就和Azure門戶中的Content-MD5值一樣：

image.png

示例代碼如下：

        static async Task GetBlobMD5Async(string connectionString,string containerName)
        {
            //// Create a BlobServiceClient object which will be used to create a container client
            BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);
            BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);
 
            Console.WriteLine("Listing blobs...");
            // List all blobs in the container
            await foreach (BlobItem blobItem in containerClient.GetBlobsAsync())
            {
                Console.WriteLine("\t" + blobItem.Name);
 
                BlobClient bclient = containerClient.GetBlobClient(blobItem.Name);
 
                // Get the blob properties
                BlobProperties properties = await bclient.GetPropertiesAsync();
 
                // Display some of the blob's property values
                Console.WriteLine($"\t\t ContentLanguage: {properties.ContentLanguage}");
                Console.WriteLine($"\t\t ContentType: {properties.ContentType}");
                Console.WriteLine($"\t\t CreatedOn: {properties.CreatedOn}");
                Console.WriteLine($"\t\t LastModified: {properties.LastModified}");
                Console.WriteLine($"\t\t ContentHash: {FormatHashValue(properties.ContentHash)}");
                Console.WriteLine($"\t\t ContentMD5: {Convert.ToBase64String(properties.ContentHash)}");
            }
        }
 
        public static string FormatHashValue(byte[] contentHash)
        {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < contentHash.Length; i++)
            {
                sb.Append(contentHash[i].ToString("x2"));
            }
            return sb.ToString();
        }

參考資料

如何調(diào)用 API 獲取 Azure File 存儲中文件的 MD5值：https://docs.azure.cn/zh-cn/articles/azure-operations-guide/storage/aog-storage-blob-file-md5

BlobProperties.ContentHash Property: https://learn.microsoft.com/en-us/dotnet/api/azure.storage.blobs.models.blobproperties.contenthash?view=azure-dotnet

Manage blob properties and metadata with .NET ： https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blob-properties-metadata#set-and-retrieve-properties

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