Azure Storage Blob SDK for Java

Build blob storage applications using the Azure Storage Blob SDK for Java.

Installation

<dependency> <groupId>com.azure</groupId> <artifactId>azure-storage-blob</artifactId> <version>12.33.0</version> </dependency>

Client Creation

BlobServiceClient

import com.azure.storage.blob.BlobServiceClient; import com.azure.storage.blob.BlobServiceClientBuilder;

// With SAS token BlobServiceClient serviceClient = new BlobServiceClientBuilder() .endpoint("<storage-account-url>") .sasToken("<sas-token>") .buildClient();

// With connection string BlobServiceClient serviceClient = new BlobServiceClientBuilder() .connectionString("<connection-string>") .buildClient();

With DefaultAzureCredential

import com.azure.identity.DefaultAzureCredentialBuilder;

BlobServiceClient serviceClient = new BlobServiceClientBuilder() .endpoint("<storage-account-url>") .credential(new DefaultAzureCredentialBuilder().build()) .buildClient();

BlobContainerClient

import com.azure.storage.blob.BlobContainerClient;

// From service client BlobContainerClient containerClient = serviceClient.getBlobContainerClient("mycontainer");

// Direct construction BlobContainerClient containerClient = new BlobContainerClientBuilder() .connectionString("<connection-string>") .containerName("mycontainer") .buildClient();

BlobClient

import com.azure.storage.blob.BlobClient;

// From container client BlobClient blobClient = containerClient.getBlobClient("myblob.txt");

// With directory structure BlobClient blobClient = containerClient.getBlobClient("folder/subfolder/myblob.txt");

// Direct construction BlobClient blobClient = new BlobClientBuilder() .connectionString("<connection-string>") .containerName("mycontainer") .blobName("myblob.txt") .buildClient();

Core Patterns

Create Container

// Create container serviceClient.createBlobContainer("mycontainer");

// Create if not exists BlobContainerClient container = serviceClient.createBlobContainerIfNotExists("mycontainer");

// From container client containerClient.create(); containerClient.createIfNotExists();

Upload Data

import com.azure.core.util.BinaryData;

// Upload string String data = "Hello, Azure Blob Storage!"; blobClient.upload(BinaryData.fromString(data));

// Upload with overwrite blobClient.upload(BinaryData.fromString(data), true);

Upload from File

blobClient.uploadFromFile("local-file.txt");

// With overwrite blobClient.uploadFromFile("local-file.txt", true);

Upload from Stream

import com.azure.storage.blob.specialized.BlockBlobClient;

BlockBlobClient blockBlobClient = blobClient.getBlockBlobClient();

try (ByteArrayInputStream dataStream = new ByteArrayInputStream(data.getBytes())) { blockBlobClient.upload(dataStream, data.length()); }

Upload with Options

import com.azure.storage.blob.models.BlobHttpHeaders; import com.azure.storage.blob.options.BlobParallelUploadOptions;

BlobHttpHeaders headers = new BlobHttpHeaders() .setContentType("text/plain") .setCacheControl("max-age=3600");

Map<String, String> metadata = Map.of("author", "john", "version", "1.0");

try (InputStream stream = new FileInputStream("large-file.bin")) { BlobParallelUploadOptions options = new BlobParallelUploadOptions(stream) .setHeaders(headers) .setMetadata(metadata);

blobClient.uploadWithResponse(options, null, Context.NONE);

}

Upload if Not Exists

import com.azure.storage.blob.models.BlobRequestConditions;

BlobParallelUploadOptions options = new BlobParallelUploadOptions(inputStream, length) .setRequestConditions(new BlobRequestConditions().setIfNoneMatch("*"));

blobClient.uploadWithResponse(options, null, Context.NONE);

Download Data

// Download to BinaryData BinaryData content = blobClient.downloadContent(); String text = content.toString();

// Download to file blobClient.downloadToFile("downloaded-file.txt");

Download to Stream

try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) { blobClient.downloadStream(outputStream); byte[] data = outputStream.toByteArray(); }

Download with InputStream

import com.azure.storage.blob.specialized.BlobInputStream;

try (BlobInputStream blobIS = blobClient.openInputStream()) { byte[] buffer = new byte[1024]; int bytesRead; while ((bytesRead = blobIS.read(buffer)) != -1) { // Process buffer } }

Upload via OutputStream

import com.azure.storage.blob.specialized.BlobOutputStream;

try (BlobOutputStream blobOS = blobClient.getBlockBlobClient().getBlobOutputStream()) { blobOS.write("Data to upload".getBytes()); }

List Blobs

import com.azure.storage.blob.models.BlobItem;

// List all blobs for (BlobItem blobItem : containerClient.listBlobs()) { System.out.println("Blob: " + blobItem.getName()); }

// List with prefix (virtual directory) import com.azure.storage.blob.models.ListBlobsOptions;

ListBlobsOptions options = new ListBlobsOptions().setPrefix("folder/"); for (BlobItem blobItem : containerClient.listBlobs(options, null)) { System.out.println("Blob: " + blobItem.getName()); }

List Blobs by Hierarchy

import com.azure.storage.blob.models.BlobListDetails;

String delimiter = "/"; ListBlobsOptions options = new ListBlobsOptions() .setPrefix("data/") .setDetails(new BlobListDetails().setRetrieveMetadata(true));

for (BlobItem item : containerClient.listBlobsByHierarchy(delimiter, options, null)) { if (item.isPrefix()) { System.out.println("Directory: " + item.getName()); } else { System.out.println("Blob: " + item.getName()); } }

Delete Blob

blobClient.delete();

// Delete if exists blobClient.deleteIfExists();

// Delete with snapshots import com.azure.storage.blob.models.DeleteSnapshotsOptionType; blobClient.deleteWithResponse(DeleteSnapshotsOptionType.INCLUDE, null, null, Context.NONE);

Copy Blob

import com.azure.storage.blob.models.BlobCopyInfo; import com.azure.core.util.polling.SyncPoller;

// Async copy (for large blobs or cross-account) SyncPoller<BlobCopyInfo, Void> poller = blobClient.beginCopy("<source-blob-url>", Duration.ofSeconds(1)); poller.waitForCompletion();

// Sync copy from URL (for same account) blobClient.copyFromUrl("<source-blob-url>");

Generate SAS Token

import com.azure.storage.blob.sas.*; import java.time.OffsetDateTime;

// Blob-level SAS BlobSasPermission permissions = new BlobSasPermission().setReadPermission(true); OffsetDateTime expiry = OffsetDateTime.now().plusDays(1);

BlobServiceSasSignatureValues sasValues = new BlobServiceSasSignatureValues(expiry, permissions); String sasToken = blobClient.generateSas(sasValues);

// Container-level SAS BlobContainerSasPermission containerPermissions = new BlobContainerSasPermission() .setReadPermission(true) .setListPermission(true);

BlobServiceSasSignatureValues containerSasValues = new BlobServiceSasSignatureValues(expiry, containerPermissions); String containerSas = containerClient.generateSas(containerSasValues);

Blob Properties and Metadata

import com.azure.storage.blob.models.BlobProperties;

// Get properties BlobProperties properties = blobClient.getProperties(); System.out.println("Size: " + properties.getBlobSize()); System.out.println("Content-Type: " + properties.getContentType()); System.out.println("Last Modified: " + properties.getLastModified());

// Set metadata Map<String, String> metadata = Map.of("key1", "value1", "key2", "value2"); blobClient.setMetadata(metadata);

// Set HTTP headers BlobHttpHeaders headers = new BlobHttpHeaders() .setContentType("application/json") .setCacheControl("max-age=86400"); blobClient.setHttpHeaders(headers);

Lease Blob

import com.azure.storage.blob.specialized.BlobLeaseClient; import com.azure.storage.blob.specialized.BlobLeaseClientBuilder;

BlobLeaseClient leaseClient = new BlobLeaseClientBuilder() .blobClient(blobClient) .buildClient();

// Acquire lease (-1 for infinite) String leaseId = leaseClient.acquireLease(60);

// Renew lease leaseClient.renewLease();

// Release lease leaseClient.releaseLease();

Error Handling

import com.azure.storage.blob.models.BlobStorageException;

try { blobClient.download(outputStream); } catch (BlobStorageException e) { System.out.println("Status: " + e.getStatusCode()); System.out.println("Error code: " + e.getErrorCode()); // 404 = Blob not found // 409 = Conflict (lease, etc.) }

Proxy Configuration

import com.azure.core.http.ProxyOptions; import com.azure.core.http.netty.NettyAsyncHttpClientBuilder; import java.net.InetSocketAddress;

ProxyOptions proxyOptions = new ProxyOptions( ProxyOptions.Type.HTTP, new InetSocketAddress("localhost", 8888));

BlobServiceClient client = new BlobServiceClientBuilder() .endpoint("<endpoint>") .sasToken("<sas-token>") .httpClient(new NettyAsyncHttpClientBuilder().proxy(proxyOptions).build()) .buildClient();

Environment Variables

AZURE_STORAGE_CONNECTION_STRING=DefaultEndpointsProtocol=https;AccountName=... AZURE_STORAGE_ACCOUNT_URL=https://<account>.blob.core.windows.net

Trigger Phrases

• "Azure Blob Storage Java"

• "upload download blob"

• "blob container SDK"

• "storage streaming"

• "SAS token generation"

• "blob metadata properties"