azure-storage-blob-java

Microsoft ｜ 雲端與基礎設施 ｜ 原文 ｜ MIT

用 Java 對 Azure Blob Storage 上傳、下載、列出與管理檔案

---
name: azure-storage-blob-java
description: 用 Java 版的 Azure Storage Blob SDK 建構 blob 儲存應用。用於在 Azure Blob Storage 上傳、下載或管理檔案、操作 container，或實作串流資料操作。
license: MIT
metadata:
  author: Microsoft
  version: "1.0.0"
  package: com.azure:azure-storage-blob
---

# Java 版 Azure Storage Blob SDK

用 Java 版的 Azure Storage Blob SDK 建構 blob 儲存應用。

## 安裝

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

## 建立 Client

### BlobServiceClient

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

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

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

### 搭配 DefaultAzureCredential

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

// 本機開發：DefaultAzureCredential。Production：設定 AZURE_TOKEN_CREDENTIALS=prod 或 AZURE_TOKEN_CREDENTIALS=<specific_credential>
TokenCredential credential = new DefaultAzureCredentialBuilder()
    .requireEnvVars(AzureIdentityEnvVars.AZURE_TOKEN_CREDENTIALS)
    .build();
// 或在 production 直接用特定的 credential：
// 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

```java
import com.azure.storage.blob.BlobContainerClient;

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

// 直接建構
BlobContainerClient containerClient = new BlobContainerClientBuilder()
    .connectionString("<connection-string>")
    .containerName("mycontainer")
    .buildClient();
```

### BlobClient

```java
import com.azure.storage.blob.BlobClient;

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

// 含目錄結構
BlobClient blobClient = containerClient.getBlobClient("folder/subfolder/myblob.txt");

// 直接建構
BlobClient blobClient = new BlobClientBuilder()
    .connectionString("<connection-string>")
    .containerName("mycontainer")
    .blobName("myblob.txt")
    .buildClient();
```

## 核心模式

### 建立 Container

```java
// 建立 container
serviceClient.createBlobContainer("mycontainer");

// 不存在才建立
BlobContainerClient container = serviceClient.createBlobContainerIfNotExists("mycontainer");

// 從 container client 建立
containerClient.create();
containerClient.createIfNotExists();
```

### 上傳資料

```java
import com.azure.core.util.BinaryData;

// 上傳字串
String data = "Hello, Azure Blob Storage!";
blobClient.upload(BinaryData.fromString(data));

// 上傳並允許覆寫
blobClient.upload(BinaryData.fromString(data), true);
```

### 從檔案上傳

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

// 允許覆寫
blobClient.uploadFromFile("local-file.txt", true);
```

### 從 Stream 上傳

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

BlockBlobClient blockBlobClient = blobClient.getBlockBlobClient();

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

### 帶選項上傳

```java
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);
}
```

### 不存在才上傳

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

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

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

### 下載資料

```java
// 下載成 BinaryData
BinaryData content = blobClient.downloadContent();
String text = content.toString();

// 下載到檔案
blobClient.downloadToFile("downloaded-file.txt");
```

### 下載到 Stream

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

### 用 InputStream 下載

```java
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) {
        // 處理 buffer
    }
}
```

### 透過 OutputStream 上傳

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

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

### 列出 Blob

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

// 列出所有 blob
for (BlobItem blobItem : containerClient.listBlobs()) {
    System.out.println("Blob: " + blobItem.getName());
}

// 用 prefix 列出（虛擬目錄）
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());
}
```

### 依階層列出 Blob

```java
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());
    }
}
```

### 刪除 Blob

```java
blobClient.delete();

// 存在才刪除
blobClient.deleteIfExists();

// 連同 snapshot 一起刪除
import com.azure.storage.blob.models.DeleteSnapshotsOptionType;
blobClient.deleteWithResponse(DeleteSnapshotsOptionType.INCLUDE, null, null, Context.NONE);
```

### 複製 Blob

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

// 非同步複製（大型 blob 或跨 account）
SyncPoller<BlobCopyInfo, Void> poller = blobClient.beginCopy("<source-blob-url>", Duration.ofSeconds(1));
poller.waitForCompletion();

// 從 URL 同步複製（同一個 account）
blobClient.copyFromUrl("<source-blob-url>");
```

### 產生 SAS Token

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

// Blob 層級的 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 層級的 SAS
BlobContainerSasPermission containerPermissions = new BlobContainerSasPermission()
    .setReadPermission(true)
    .setListPermission(true);
    
BlobServiceSasSignatureValues containerSasValues = new BlobServiceSasSignatureValues(expiry, containerPermissions);
String containerSas = containerClient.generateSas(containerSasValues);
```

### Blob 屬性與 Metadata

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

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

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

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

### Blob Lease

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

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

// 取得 lease（-1 表示無限期）
String leaseId = leaseClient.acquireLease(60);

// 續期 lease
leaseClient.renewLease();

// 釋放 lease
leaseClient.releaseLease();
```

## 錯誤處理

```java
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 = 找不到 blob
    // 409 = 衝突（lease 等）
}
```

## Proxy 設定

```java
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();
```

## 環境變數

```bash
AZURE_STORAGE_CONNECTION_STRING=DefaultEndpointsProtocol=https;AccountName=...  # Entra ID 驗證的替代方案
AZURE_STORAGE_ACCOUNT_URL=https://<account>.blob.core.windows.net  # 所有驗證方式都必填
AZURE_TOKEN_CREDENTIALS=prod  # 只有在 production 使用 DefaultAzureCredential 時才需要
```

## 觸發用語

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

---
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

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

## Client Creation

### BlobServiceClient

```java
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

```java
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

```java
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

```java
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

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

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

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

### Upload Data

```java
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

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

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

### Upload from Stream

```java
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

```java
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

```java
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

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

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

### Download to Stream

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

### Download with InputStream

```java
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

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

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

### List Blobs

```java
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

```java
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

```java
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

```java
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

```java
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

```java
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

```java
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

```java
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

```java
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

```bash
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"