azure-storage-blob-java

name	azure-storage-blob-java
description	Build blob storage applications with Azure Storage Blob SDK for Java. Use when uploading, downloading, or managing files in Azure Blob Storage, working with containers, or implementing streaming data operations.
license	MIT
metadata	{"author":"Microsoft","version":"1.0.0","package":"com.azure:azure-storage-blob"}

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.core.credential.TokenCredential;
import com.azure.identity.AzureIdentityEnvVars;
import com.azure.identity.DefaultAzureCredentialBuilder;
import com.azure.identity.ManagedIdentityCredentialBuilder;

// Local dev: DefaultAzureCredential. Production: set AZURE_TOKEN_CREDENTIALS=prod or AZURE_TOKEN_CREDENTIALS=<specific_credential>
TokenCredential credential = new DefaultAzureCredentialBuilder()
    .requireEnvVars(AzureIdentityEnvVars.AZURE_TOKEN_CREDENTIALS)
    .build();
// Or use a specific credential directly in production:
// See https://learn.microsoft.com/java/api/overview/azure/identity-readme?view=azure-java-stable#credential-classes
// TokenCredential credential = new ManagedIdentityCredentialBuilder().build();

BlobServiceClient serviceClient = new BlobServiceClientBuilder()
    .endpoint("<storage-account-url>")
    .credential(credential)
    .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=...  # Alternative to Entra ID auth
AZURE_STORAGE_ACCOUNT_URL=https://<account>.blob.core.windows.net  # Required for all auth methods
AZURE_TOKEN_CREDENTIALS=prod  # Required only if DefaultAzureCredential is used in production

Trigger Phrases

• "Azure Blob Storage Java"
• "upload download blob"
• "blob container SDK"
• "storage streaming"
• "SAS token generation"
• "blob metadata properties"