azure-storage-blob-java

用于 Java 的 Azure Storage Blob SDK

使用用于 Java 的 Azure Storage Blob SDK 构建 Blob 存储应用程序。

安装

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

创建客户端

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();

使用 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();

存储和持有者令牌范围

在调整这些独立代码片段之前，请核实账户、容器和密钥，以及当前 SDK 的签名。覆盖、删除快照、替换元数据/标头以及跨账户复制，都需要对目标对象拥有精确授权，并在需要时使用并发条件。限制内存中的下载大小；对于大型 Blob，优先使用流式处理。SAS 是持有者凭据：请对对象和调用方进行授权，将权限和有效期控制在最低限度，使用 HTTPS，避免记录到日志中，并在适用时优先使用用户委派 SAS。generateSas 需要适当的签名凭据；仅使用 DefaultAzureCredential 并不能让该方法具备账户密钥签名能力。请检查复制操作的完成状态和失败情况，不要假定等待就能保证成功。

核心模式

创建容器

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

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

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

上传数据

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);

从文件上传

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

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

从流上传

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

BlockBlobClient blockBlobClient = blobClient.getBlockBlobClient();

byte[] utf8 = data.getBytes(java.nio.charset.StandardCharsets.UTF_8);
try (ByteArrayInputStream dataStream = new ByteArrayInputStream(utf8)) {
    blockBlobClient.upload(dataStream, utf8.length);
}

使用选项上传

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);
}

仅在不存在时上传

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

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

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

下载数据

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

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

下载到流

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

使用 InputStream 下载

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
    }
}

通过 OutputStream 上传

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

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

列出 Blob

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());
}

按层级列出 Blob

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());
    }
}

删除 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);

复制 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>");

生成 SAS 令牌

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 属性和元数据

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);

租用 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();

错误处理

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.)
}

代理配置

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();

环境变量

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

触发短语

• “Azure Blob Storage Java”
• “上传下载 Blob”
• “Blob 容器 SDK”
• “存储流式处理”
• “SAS 令牌生成”
• “Blob 元数据属性”

适用场景

当需要执行概述中所述的工作流或操作时，可使用此技能。

限制

• 仅当任务明确符合上述范围时，才使用此技能。
• 不要将输出视为环境特定验证、测试或专家审核的替代品。
• 如果缺少必需的输入、权限、安全边界或成功标准，请停止并要求澄清。