Use blob index tags to manage and find data with Java
This article shows how to use blob index tags to manage and find data using the Azure Storage client library for Java.
Prerequisites
- This article assumes you already have a project set up to work with the Azure Blob Storage client library for Java. To learn about setting up your project, including package installation, adding
import
directives, and creating an authorized client object, see Get Started with Azure Storage and Java. - The authorization mechanism must have permissions to work with blob index tags. To learn more, see the authorization guidance for the following REST API operations:
About blob index tags
Blob index tags categorize data in your storage account using key-value tag attributes. These tags are automatically indexed and exposed as a searchable multi-dimensional index to easily find data. This article shows you how to set, get, and find data using blob index tags.
Blob index tags aren't supported for storage accounts with hierarchical namespace enabled. To learn more about the blob index tag feature along with known issues and limitations, see Manage and find Azure Blob data with blob index tags.
Set tags
You can set index tags if your code has authorized access to blob data through one of the following mechanisms:
- Security principal that is assigned an Azure RBAC role with the Microsoft.Storage/storageAccounts/blobServices/containers/blobs/tags/write action. The Storage Blob Data Owner is a built-in role that includes this action.
- Shared Access Signature (SAS) with permission to access the blob's tags (
t
permission) - Account key
For more information, see Setting blob index tags.
You can set tags by using the following method:
The specified tags in this method will replace existing tags. If old values must be preserved, they must be downloaded and included in the call to this method. The following example shows how to set tags:
public void setBlobTags(BlobClient blobClient) {
// Get any existing tags for the blob if they need to be preserved
Map<String, String> tags = blobClient.getTags();
// Add or modify tags
tags.put("Sealed", "false");
tags.put("Content", "image");
tags.put("Date", "2022-01-01");
// setTags will replace existing tags with the map entries we pass in
blobClient.setTags(tags);
}
You can delete all tags by passing an empty Map
object into the setTags
method:
public void clearBlobTags(BlobClient blobClient) {
Map<String, String> tags = new HashMap<String, String>();
blobClient.setTags(tags);
}
Get tags
You can get index tags if your code has authorized access to blob data through one of the following mechanisms:
- Security principal that is assigned an Azure RBAC role with the Microsoft.Storage/storageAccounts/blobServices/containers/blobs/tags/read action. The Storage Blob Data Owner is a built-in role that includes this action.
- Shared Access Signature (SAS) with permission to access the blob's tags (
t
permission) - Account key
For more information, see Getting and listing blob index tags.
You can get tags by using the following method:
The following example shows how to retrieve and iterate over the blob's tags:
public void getBlobTags(BlobClient blobClient) {
Map<String, String> tags = blobClient.getTags();
System.out.println("Blob tags:");
for (Map.Entry<String, String> entry : tags.entrySet())
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
Filter and find data with blob index tags
You can use index tags to find and filter data if your code has authorized access to blob data through one of the following mechanisms:
- Security principal that is assigned an Azure RBAC role with the Microsoft.Storage/storageAccounts/blobServices/containers/blobs/filter/action action. The Storage Blob Data Owner is a built-in role that includes this action.
- Shared Access Signature (SAS) with permission to filter blobs by tags (
f
permission) - Account key
For more information, see Finding data using blob index tags.
Note
You can't use index tags to retrieve previous versions. Tags for previous versions aren't passed to the blob index engine. For more information, see Conditions and known issues.
You can find data by using the following method:
The following example finds all blobs tagged as an image:
public void findBlobsByTag(BlobContainerClient blobContainerClient) {
String query = "\"Content\"='image'";
blobContainerClient.findBlobsByTags(query)
.forEach(blob -> System.out.printf("Name: %s%n", blob.getName()));
}
Resources
To learn more about how to use index tags to manage and find data using the Azure Blob Storage client library for Java, see the following resources.
REST API operations
The Azure SDK for Java contains libraries that build on top of the Azure REST API, allowing you to interact with REST API operations through familiar Java paradigms. The client library methods for managing and using blob index tags use the following REST API operations:
- Get Blob Tags (REST API)
- Set Blob Tags (REST API)
- Find Blobs by Tags (REST API)
Code samples
Client library resources
See also
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