查看和修改对象元数据

转到概念

本页面介绍了如何查看和修改与存储在 Cloud Storage 中的对象关联的元数据。

本页面没有介绍如何查看或修改 Identity and Access Management (IAM) 政策或对象访问控制列表 (ACL)（均可以控制能够访问您的数据的人员）。如需介绍如何完成这些任务的指南，请参阅使用 IAM 权限以及创建和管理 ACL。

查看对象元数据

如需查看与对象关联的元数据，请执行以下操作：

控制台

  1. 在 Google Cloud Console 中，转到 Cloud Storage 浏览器页面。

    转到浏览器

  2. 在存储分区列表中，点击存放所需对象的存储分区的名称。

    此时会打开“存储分区详情”页面，其中“对象”标签页已选中。

  3. 导航到可能位于文件夹中的对象。

    某些对象元数据值（例如对象的大小和存储类别）会随对象名称显示。

  4. 点击与对象关联的更多操作菜单 ()。

  5. 点击修改元数据。

    出现的叠加窗口中会显示对象当前的可修改元数据值。

如需了解如何获取有关 Cloud Storage 浏览器中失败操作的详细错误信息，请参阅问题排查。

gsutil

使用 gsutil stat 命令：

gsutil stat gs://BUCKET_NAME/OBJECT_NAME

其中：

  • BUCKET_NAME 是包含要查看其元数据的对象的存储分区的名称，例如 my-awesome-bucket。
  • OBJECT_NAME 是要查看其元数据的对象的名称，例如 cat.jpeg。

如果成功，响应类似于以下示例：

gs://my-awesome-bucket/cat.jpeg:
Creation time:          Fri, 03 Feb 2017 22:43:31 GMT
Update time:            Wed, 10 May 2017 18:33:07 GMT
Storage class:          STANDARD
Content-Length:         11012
Content-Type:           image/jpeg
Metadata:
    Breed:              Tabby
Hash (crc32c):          HQbzrB==
Hash (md5):             OBydg25+pPG1Cwawjsl7DA==
ETag:                   CJCh9apA9dECAEs=
Generation:             1486161811706000
Metageneration:         11

代码示例

C++

如需了解详情，请参阅 Cloud Storage C++ API 参考文档。

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name) {
  StatusOr<gcs::ObjectMetadata> object_metadata =
      client.GetObjectMetadata(bucket_name, object_name);

  if (!object_metadata) {
    throw std::runtime_error(object_metadata.status().message());
  }

  std::cout << "The metadata for object " << object_metadata->name()
            << " in bucket " << object_metadata->bucket() << " is "
            << *object_metadata << "\n";
}

C#

如需了解详情，请参阅 Cloud Storage C# API 参考文档。 


using Google.Cloud.Storage.V1;
using System;

public class GetMetadataSample
{
    public Google.Apis.Storage.v1.Data.Object GetMetadata(
        string bucketName = "your-unique-bucket-name",
        string objectName = "your-object-name")
    {
        var storage = StorageClient.Create();
        var storageObject = storage.GetObject(bucketName, objectName, new GetObjectOptions { Projection = Projection.Full });
        Console.WriteLine($"Bucket:\t{storageObject.Bucket}");
        Console.WriteLine($"CacheControl:\t{storageObject.CacheControl}");
        Console.WriteLine($"ComponentCount:\t{storageObject.ComponentCount}");
        Console.WriteLine($"ContentDisposition:\t{storageObject.ContentDisposition}");
        Console.WriteLine($"ContentEncoding:\t{storageObject.ContentEncoding}");
        Console.WriteLine($"ContentLanguage:\t{storageObject.ContentLanguage}");
        Console.WriteLine($"ContentType:\t{storageObject.ContentType}");
        Console.WriteLine($"Crc32c:\t{storageObject.Crc32c}");
        Console.WriteLine($"ETag:\t{storageObject.ETag}");
        Console.WriteLine($"Generation:\t{storageObject.Generation}");
        Console.WriteLine($"Id:\t{storageObject.Id}");
        Console.WriteLine($"Kind:\t{storageObject.Kind}");
        Console.WriteLine($"KmsKeyName:\t{storageObject.KmsKeyName}");
        Console.WriteLine($"Md5Hash:\t{storageObject.Md5Hash}");
        Console.WriteLine($"MediaLink:\t{storageObject.MediaLink}");
        Console.WriteLine($"Metageneration:\t{storageObject.Metageneration}");
        Console.WriteLine($"Name:\t{storageObject.Name}");
        Console.WriteLine($"Size:\t{storageObject.Size}");
        Console.WriteLine($"StorageClass:\t{storageObject.StorageClass}");
        Console.WriteLine($"TimeCreated:\t{storageObject.TimeCreated}");
        Console.WriteLine($"Updated:\t{storageObject.Updated}");
        bool eventBasedHold = storageObject.EventBasedHold ?? false;
        Console.WriteLine("Event-based hold enabled? {0}", eventBasedHold);
        bool temporaryHold = storageObject.TemporaryHold ?? false;
        Console.WriteLine("Temporary hold enabled? {0}", temporaryHold);
        Console.WriteLine($"RetentionExpirationTime\t{storageObject.RetentionExpirationTime}");
        if (storageObject.Metadata != null)
        {
            Console.WriteLine("Metadata: ");
            foreach (var metadata in storageObject.Metadata)
            {
                Console.WriteLine($"{metadata.Key}:\t{metadata.Value}");
            }
        }
        Console.WriteLine($"CustomTime:\t{storageObject.CustomTime}");
        return storageObject;
    }
}

Go

如需了解详情，请参阅 Cloud Storage Go API 参考文档。 

import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/storage"
)

// getMetadata prints all of the object attributes.
func getMetadata(w io.Writer, bucket, object string) (*storage.ObjectAttrs, error) {
	// bucket := "bucket-name"
	// object := "object-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	o := client.Bucket(bucket).Object(object)
	attrs, err := o.Attrs(ctx)
	if err != nil {
		return nil, fmt.Errorf("Object(%q).Attrs: %v", object, err)
	}
	fmt.Fprintf(w, "Bucket: %v\n", attrs.Bucket)
	fmt.Fprintf(w, "CacheControl: %v\n", attrs.CacheControl)
	fmt.Fprintf(w, "ContentDisposition: %v\n", attrs.ContentDisposition)
	fmt.Fprintf(w, "ContentEncoding: %v\n", attrs.ContentEncoding)
	fmt.Fprintf(w, "ContentLanguage: %v\n", attrs.ContentLanguage)
	fmt.Fprintf(w, "ContentType: %v\n", attrs.ContentType)
	fmt.Fprintf(w, "Crc32c: %v\n", attrs.CRC32C)
	fmt.Fprintf(w, "Generation: %v\n", attrs.Generation)
	fmt.Fprintf(w, "KmsKeyName: %v\n", attrs.KMSKeyName)
	fmt.Fprintf(w, "Md5Hash: %v\n", attrs.MD5)
	fmt.Fprintf(w, "MediaLink: %v\n", attrs.MediaLink)
	fmt.Fprintf(w, "Metageneration: %v\n", attrs.Metageneration)
	fmt.Fprintf(w, "Name: %v\n", attrs.Name)
	fmt.Fprintf(w, "Size: %v\n", attrs.Size)
	fmt.Fprintf(w, "StorageClass: %v\n", attrs.StorageClass)
	fmt.Fprintf(w, "TimeCreated: %v\n", attrs.Created)
	fmt.Fprintf(w, "Updated: %v\n", attrs.Updated)
	fmt.Fprintf(w, "Event-based hold enabled? %t\n", attrs.EventBasedHold)
	fmt.Fprintf(w, "Temporary hold enabled? %t\n", attrs.TemporaryHold)
	fmt.Fprintf(w, "Retention expiration time %v\n", attrs.RetentionExpirationTime)
	fmt.Fprintf(w, "Custom time %v\n", attrs.CustomTime)
	fmt.Fprintf(w, "\n\nMetadata\n")
	for key, value := range attrs.Metadata {
		fmt.Fprintf(w, "\t%v = %v\n", key, value)
	}
	return attrs, nil
}

Java

如需了解详情，请参阅 Cloud Storage Java API 参考文档。

import com.google.cloud.storage.Blob;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageException;
import com.google.cloud.storage.StorageOptions;
import java.util.Date;
import java.util.Map;

public class GetObjectMetadata {
  public static void getObjectMetadata(String projectId, String bucketName, String blobName)
      throws StorageException {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The ID of your GCS object
    // String objectName = "your-object-name";

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    // Select all fields
    // Fields can be selected individually e.g. Storage.BlobField.CACHE_CONTROL
    Blob blob =
        storage.get(bucketName, blobName, Storage.BlobGetOption.fields(Storage.BlobField.values()));

    // Print blob metadata
    System.out.println("Bucket: " + blob.getBucket());
    System.out.println("CacheControl: " + blob.getCacheControl());
    System.out.println("ComponentCount: " + blob.getComponentCount());
    System.out.println("ContentDisposition: " + blob.getContentDisposition());
    System.out.println("ContentEncoding: " + blob.getContentEncoding());
    System.out.println("ContentLanguage: " + blob.getContentLanguage());
    System.out.println("ContentType: " + blob.getContentType());
    System.out.println("CustomTime: " + blob.getCustomTime());
    System.out.println("Crc32c: " + blob.getCrc32c());
    System.out.println("Crc32cHexString: " + blob.getCrc32cToHexString());
    System.out.println("ETag: " + blob.getEtag());
    System.out.println("Generation: " + blob.getGeneration());
    System.out.println("Id: " + blob.getBlobId());
    System.out.println("KmsKeyName: " + blob.getKmsKeyName());
    System.out.println("Md5Hash: " + blob.getMd5());
    System.out.println("Md5HexString: " + blob.getMd5ToHexString());
    System.out.println("MediaLink: " + blob.getMediaLink());
    System.out.println("Metageneration: " + blob.getMetageneration());
    System.out.println("Name: " + blob.getName());
    System.out.println("Size: " + blob.getSize());
    System.out.println("StorageClass: " + blob.getStorageClass());
    System.out.println("TimeCreated: " + new Date(blob.getCreateTime()));
    System.out.println("Last Metadata Update: " + new Date(blob.getUpdateTime()));
    Boolean temporaryHoldIsEnabled = (blob.getTemporaryHold() != null && blob.getTemporaryHold());
    System.out.println("temporaryHold: " + (temporaryHoldIsEnabled ? "enabled" : "disabled"));
    Boolean eventBasedHoldIsEnabled =
        (blob.getEventBasedHold() != null && blob.getEventBasedHold());
    System.out.println("eventBasedHold: " + (eventBasedHoldIsEnabled ? "enabled" : "disabled"));
    if (blob.getRetentionExpirationTime() != null) {
      System.out.println("retentionExpirationTime: " + new Date(blob.getRetentionExpirationTime()));
    }
    if (blob.getMetadata() != null) {
      System.out.println("\n\n\nUser metadata:");
      for (Map.Entry<String, String> userMetadata : blob.getMetadata().entrySet()) {
        System.out.println(userMetadata.getKey() + "=" + userMetadata.getValue());
      }
    }
  }
}

Node.js

如需了解详情，请参阅 Cloud Storage Node.js API 参考文档。

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const fileName = 'your-file-name';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function getMetadata() {
  // Gets the metadata for the file
  const [metadata] = await storage
    .bucket(bucketName)
    .file(fileName)
    .getMetadata();

  console.log(`Bucket: ${metadata.bucket}`);
  console.log(`CacheControl: ${metadata.cacheControl}`);
  console.log(`ComponentCount: ${metadata.componentCount}`);
  console.log(`ContentDisposition: ${metadata.contentDisposition}`);
  console.log(`ContentEncoding: ${metadata.contentEncoding}`);
  console.log(`ContentLanguage: ${metadata.contentLanguage}`);
  console.log(`ContentType: ${metadata.contentType}`);
  console.log(`CustomTime: ${metadata.customTime}`);
  console.log(`Crc32c: ${metadata.crc32c}`);
  console.log(`ETag: ${metadata.etag}`);
  console.log(`Generation: ${metadata.generation}`);
  console.log(`Id: ${metadata.id}`);
  console.log(`KmsKeyName: ${metadata.kmsKeyName}`);
  console.log(`Md5Hash: ${metadata.md5Hash}`);
  console.log(`MediaLink: ${metadata.mediaLink}`);
  console.log(`Metageneration: ${metadata.metageneration}`);
  console.log(`Name: ${metadata.name}`);
  console.log(`Size: ${metadata.size}`);
  console.log(`StorageClass: ${metadata.storageClass}`);
  console.log(`TimeCreated: ${new Date(metadata.timeCreated)}`);
  console.log(`Last Metadata Update: ${new Date(metadata.updated)}`);
  console.log(
    `temporaryHold: ${metadata.temporaryHold ? 'enabled' : 'disabled'}`
  );
  console.log(
    `eventBasedHold: ${metadata.eventBasedHold ? 'enabled' : 'disabled'}`
  );
  if (metadata.retentionExpirationTime) {
    console.log(
      `retentionExpirationTime: ${new Date(metadata.retentionExpirationTime)}`
    );
  }
  if (metadata.metadata) {
    console.log('\n\n\nUser metadata:');
    for (const key in metadata.metadata) {
      console.log(`${key}=${metadata.metadata[key]}`);
    }
  }
}

getMetadata().catch(console.error);

PHP

如需了解详情，请参阅 Cloud Storage PHP API 参考文档。 

use Google\Cloud\Storage\StorageClient;

/**
 * List object metadata.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $objectName The name of your Cloud Storage object.
 */
function object_metadata($bucketName, $objectName)
{
    // $bucketName = 'my-bucket';
    // $objectName = 'my-object';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $info = $object->info();
    if (isset($info['name'])) {
        printf('Blob: %s' . PHP_EOL, $info['name']);
    }
    if (isset($info['bucket'])) {
        printf('Bucket: %s' . PHP_EOL, $info['bucket']);
    }
    if (isset($info['storageClass'])) {
        printf('Storage class: %s' . PHP_EOL, $info['storageClass']);
    }
    if (isset($info['id'])) {
        printf('ID: %s' . PHP_EOL, $info['id']);
    }
    if (isset($info['size'])) {
        printf('Size: %s' . PHP_EOL, $info['size']);
    }
    if (isset($info['updated'])) {
        printf('Updated: %s' . PHP_EOL, $info['updated']);
    }
    if (isset($info['generation'])) {
        printf('Generation: %s' . PHP_EOL, $info['generation']);
    }
    if (isset($info['metageneration'])) {
        printf('Metageneration: %s' . PHP_EOL, $info['metageneration']);
    }
    if (isset($info['etag'])) {
        printf('Etag: %s' . PHP_EOL, $info['etag']);
    }
    if (isset($info['crc32c'])) {
        printf('Crc32c: %s' . PHP_EOL, $info['crc32c']);
    }
    if (isset($info['md5Hash'])) {
        printf('MD5 Hash: %s' . PHP_EOL, $info['md5Hash']);
    }
    if (isset($info['contentType'])) {
        printf('Content-type: %s' . PHP_EOL, $info['contentType']);
    }
    if (isset($info['temporaryHold'])) {
        printf('Temporary hold: %s' . PHP_EOL, ($info['temporaryHold'] ? 'enabled' : 'disabled'));
    }
    if (isset($info['eventBasedHold'])) {
        printf('Event-based hold: %s' . PHP_EOL, ($info['eventBasedHold'] ? 'enabled' : 'disabled'));
    }
    if (isset($info['retentionExpirationTime'])) {
        printf('Retention Expiration Time: %s' . PHP_EOL, $info['retentionExpirationTime']);
    }
    if (isset($info['customTime'])) {
        printf('Custom Time: %s' . PHP_EOL, $info['customTime']);
    }
    if (isset($info['metadata'])) {
        printf('Metadata: %s' . PHP_EOL, print_r($info['metadata'], true));
    }
}

Python

如需了解详情，请参阅 Cloud Storage Python API 参考文档。

from google.cloud import storage

def blob_metadata(bucket_name, blob_name):
    """Prints out a blob's metadata."""
    # bucket_name = 'your-bucket-name'
    # blob_name = 'your-object-name'

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    # Retrieve a blob, and its metadata, from Google Cloud Storage.
    # Note that `get_blob` differs from `Bucket.blob`, which does not
    # make an HTTP request.
    blob = bucket.get_blob(blob_name)

    print("Blob: {}".format(blob.name))
    print("Bucket: {}".format(blob.bucket.name))
    print("Storage class: {}".format(blob.storage_class))
    print("ID: {}".format(blob.id))
    print("Size: {} bytes".format(blob.size))
    print("Updated: {}".format(blob.updated))
    print("Generation: {}".format(blob.generation))
    print("Metageneration: {}".format(blob.metageneration))
    print("Etag: {}".format(blob.etag))
    print("Owner: {}".format(blob.owner))
    print("Component count: {}".format(blob.component_count))
    print("Crc32c: {}".format(blob.crc32c))
    print("md5_hash: {}".format(blob.md5_hash))
    print("Cache-control: {}".format(blob.cache_control))
    print("Content-type: {}".format(blob.content_type))
    print("Content-disposition: {}".format(blob.content_disposition))
    print("Content-encoding: {}".format(blob.content_encoding))
    print("Content-language: {}".format(blob.content_language))
    print("Metadata: {}".format(blob.metadata))
    print("Custom Time: {}".format(blob.custom_time))
    print("Temporary hold: ", "enabled" if blob.temporary_hold else "disabled")
    print(
        "Event based hold: ",
        "enabled" if blob.event_based_hold else "disabled",
    )
    if blob.retention_expiration_time:
        print(
            "retentionExpirationTime: {}".format(
                blob.retention_expiration_time
            )
        )

Ruby

如需了解详情，请参阅 Cloud Storage Ruby API 参考文档。 

def get_metadata bucket_name:, file_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  # The ID of your GCS object
  # file_name = "your-file-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket  = storage.bucket bucket_name
  file    = bucket.file file_name

  puts "Name: #{file.name}"
  puts "Bucket: #{bucket.name}"
  puts "Storage class: #{bucket.storage_class}"
  puts "ID: #{file.id}"
  puts "Size: #{file.size} bytes"
  puts "Created: #{file.created_at}"
  puts "Updated: #{file.updated_at}"
  puts "Generation: #{file.generation}"
  puts "Metageneration: #{file.metageneration}"
  puts "Etag: #{file.etag}"
  puts "Owners: #{file.acl.owners.join ','}"
  puts "Crc32c: #{file.crc32c}"
  puts "md5_hash: #{file.md5}"
  puts "Cache-control: #{file.cache_control}"
  puts "Content-type: #{file.content_type}"
  puts "Content-disposition: #{file.content_disposition}"
  puts "Content-encoding: #{file.content_encoding}"
  puts "Content-language: #{file.content_language}"
  puts "KmsKeyName: #{file.kms_key}"
  puts "Event-based hold enabled?: #{file.event_based_hold?}"
  puts "Temporary hold enaled?: #{file.temporary_hold?}"
  puts "Retention Expiration: #{file.retention_expires_at}"
  puts "Custom Time: #{file.custom_time}"
  puts "Metadata:"
  file.metadata.each do |key, value|
    puts " - #{key} = #{value}"
  end
end

REST API

JSON API

  1. 从 OAuth 2.0 Playground 获取授权访问令牌。将 Playground 配置为使用您自己的 OAuth 凭据。

  2. 使用 cURL，通过 GET Object 请求调用 JSON API：

    curl -X GET \
  -H "Authorization: Bearer OAUTH2_TOKEN" \
  "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/o/OBJECT_NAME"

    其中：

    • OAUTH2_TOKEN 是您在第 1 步中生成的访问令牌。
    • BUCKET_NAME 是包含要查看其元数据的对象的存储分区的名称，例如 my-bucket。
    • OBJECT_NAME 是要查看其元数据的对象的名称，例如 pets/dog.png。

XML API

  1. 从 OAuth 2.0 Playground 获取授权访问令牌。将 Playground 配置为使用您自己的 OAuth 凭据。

  2. 使用 cURL，通过 HEAD Object 请求调用 XML API：

    curl -I HEAD \
  -H "Authorization: Bearer OAUTH2_TOKEN" \
  "https://storage.googleapis.com/BUCKET_NAME/OBJECT_NAME"

    其中：

    • OAUTH2_TOKEN 是您在第 1 步中生成的访问令牌。
    • BUCKET_NAME 是包含要查看其元数据的对象的存储分区的名称，例如 my-bucket。
    • OBJECT_NAME 是要查看其元数据的对象的名称，例如 pets/dog.png。

修改对象元数据

如需修改与对象关联的元数据，请执行以下操作：

控制台

  1. 在 Google Cloud Console 中，转到 Cloud Storage 浏览器页面。

    转到浏览器

  2. 在存储分区列表中，点击存放所需对象的存储分区的名称。

    此时会打开“存储分区详情”页面，其中“对象”标签页已选中。

  3. 导航到可能位于文件夹中的对象。

  4. 点击与对象关联的更多操作菜单 ()。

  5. 点击修改元数据。

  6. 在出现的叠加窗口中，对元数据执行所需的修改。

    • 对于标准元数据字段，请修改“值”。

    • 点击 + 添加项按钮添加您自己的自定义元数据。

    • 您可以修改自定义元数据的“键”和“值”。

    • 点击关联的 X 符号以删除自定义元数据。

  7. 点击保存。

如需了解如何获取有关 Cloud Storage 浏览器中失败操作的详细错误信息，请参阅问题排查。

gsutil

使用 gsutil setmeta -h 命令：

gsutil setmeta -h "METADATA_KEY:METADATA_VALUE" gs://BUCKET_NAME/OBJECT_NAME

其中：

  • METADATA_KEY 是您想要设置的元数据键，例如 Content-Type。
  • METADATA_VALUE 是您想要设置的元数据值，例如 image/png。
  • BUCKET_NAME 是包含您要修改其元数据的对象的存储分区的名称，例如 my-bucket。
  • OBJECT_NAME 是您要修改其元数据的对象的名称，例如 pets/dog.png。

如果成功，则响应类似如下示例：

Operation completed over 1 objects.

请注意，如果您要使用 gsutil 添加自定义元数据，必须在元数据键的前面加上 x-goog-meta- 前缀，以让 gsutil 识别出这是自定义元数据属性，而非标准 HTTP 标头。元数据键本身不会与 x-goog-meta- 前缀一起存储。自定义 "METADATA_KEY:METADATA_VALUE" 的一个示例是 "x-goog-meta-dogbreed:shibainu"。

代码示例

C++

如需了解详情，请参阅 Cloud Storage C++ API 参考文档。

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name, std::string const& key,
   std::string const& value) {
  StatusOr<gcs::ObjectMetadata> object_metadata =
      client.GetObjectMetadata(bucket_name, object_name);

  if (!object_metadata) {
    throw std::runtime_error(object_metadata.status().message());
  }

  gcs::ObjectMetadata desired = *object_metadata;
  desired.mutable_metadata().emplace(key, value);

  StatusOr<gcs::ObjectMetadata> updated =
      client.UpdateObject(bucket_name, object_name, desired,
                          gcs::Generation(object_metadata->generation()));

  if (!updated) throw std::runtime_error(updated.status().message());
  std::cout << "Object updated. The full metadata after the update is: "
            << *updated << "\n";
}

C#

如需了解详情，请参阅 Cloud Storage C# API 参考文档。

如需使用 C# 修改与对象关联的元数据，请参阅 PatchObject 参考文档。

Go

如需了解详情，请参阅 Cloud Storage Go API 参考文档。 

import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/storage"
)

// setMetadata sets an object's metadata.
func setMetadata(w io.Writer, bucket, object string) error {
	// bucket := "bucket-name"
	// object := "object-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	o := client.Bucket(bucket).Object(object)
	objectAttrsToUpdate := storage.ObjectAttrsToUpdate{
		Metadata: map[string]string{
			"keyToAddOrUpdate": "value",
		},
	}
	if _, err := o.Update(ctx, objectAttrsToUpdate); err != nil {
		return fmt.Errorf("ObjectHandle(%q).Update: %v", object, err)
	}
	fmt.Fprintf(w, "Updated custom metadata for object %v in bucket %v.\n", object, bucket)
	return nil
}

Node.js

如需了解详情，请参阅 Cloud Storage Node.js API 参考文档。

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const fileName = 'your-file-name';

async function setFileMetadata() {
  // Set file metadata.
  const [metadata] = await storage
    .bucket(bucketName)
    .file(fileName)
    .setMetadata({
      // Predefinded metadata for server e.g. 'cacheControl', 'contentDisposition',
      // 'contentEncoding', 'contentLanguage', 'contentType'
      contentDisposition: 'attachment; filename*=utf-8\'\'"anotherImage.jpg"',
      contentType: 'image/jpeg',

      // A note or actionable items for user e.g. uniqueId, object description,
      // or other useful information.
      metadata: {
        description: 'file description...',
        modified: '1900-01-01',
      },
    });

  console.log(
    'Updated metadata for object',
    fileName,
    'in bucket ',
    bucketName
  );
  console.log(metadata);
}

setFileMetadata().catch(console.error);

PHP

如需了解详情，请参阅 Cloud Storage PHP API 参考文档。 

use Google\Cloud\Storage\StorageClient;

/**
 * Set a metadata key and value on the specified object.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $objectName The name of your Cloud Storage object.
 */
function set_metadata($bucketName, $objectName)
{
    // $bucketName = 'my-bucket';
    // $objectName = 'my-object';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $object->update([
        'metadata' => [
            'keyToAddOrUpdate' => 'value',
        ]
    ]);

    printf('Updated custom metadata for object %s in bucket %s', $objectName, $bucketName);
}

Python

如需了解详情，请参阅 Cloud Storage Python API 参考文档。

from google.cloud import storage

def set_blob_metadata(bucket_name, blob_name):
    """Set a blob's metadata."""
    # bucket_name = 'your-bucket-name'
    # blob_name = 'your-object-name'

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)
    blob = bucket.get_blob(blob_name)
    metadata = {'color': 'Red', 'name': 'Test'}
    blob.metadata = metadata
    blob.patch()

    print("The metadata for the blob {} is {}".format(blob.name, blob.metadata))

Ruby

如需了解详情，请参阅 Cloud Storage Ruby API 参考文档。 

def set_metadata bucket_name:, file_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  # The ID of your GCS object
  # file_name = "your-file-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket  = storage.bucket bucket_name
  file    = bucket.file file_name

  file.update do |file|
    # Fixed key file metadata
    file.content_type = "text/plain"

    # Custom file metadata
    file.metadata["your-metadata-key"] = "your-metadata-value"
  end

  puts "Metadata for #{file_name} has been updated."
end

Java

如需了解详情，请参阅 Cloud Storage Java API 参考文档。

import com.google.cloud.storage.Blob;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.HashMap;
import java.util.Map;

public class SetObjectMetadata {
  public static void setObjectMetadata(String projectId, String bucketName, String objectName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The ID of your GCS object
    // String objectName = "your-object-name";

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();
    Map<String, String> newMetadata = new HashMap<>();
    newMetadata.put("keyToAddOrUpdate", "value");
    Blob blob = storage.get(bucketName, objectName);
    // Does an upsert operation, if the key already exists it's replaced by the new value, otherwise
    // it's added.
    blob.toBuilder().setMetadata(newMetadata).build().update();

    System.out.println(
        "Updated custom metadata for object " + objectName + " in bucket " + bucketName);
  }
}

REST API

JSON API

  1. 从 OAuth 2.0 Playground 获取授权访问令牌。将 Playground 配置为使用您自己的 OAuth 凭据。

  2. 创建一个包含要修改的元数据的 .json 文件。

    如需添加或修改固定键元数据（例如 contentType），请使用以下格式：

    {
  "STANDARD_METADATA_KEY": "STANDARD_METADATA_VALUE"
}

    其中：

    • STANDARD_METADATA_KEY 是您想要添加或修改的元数据的键，例如 Content-Type。
    • STANDARD_METADATA_VALUE 是您想要添加或修改的元数据的值，例如 image/png。

    如需添加或修改自定义元数据，请使用以下格式：

    {
  "metadata": {
    "CUSTOM_METADATA_KEY": "CUSTOM_METADATA_VALUE"
  }
}

    其中：

    • CUSTOM_METADATA_KEY 是您想要添加或修改的自定义元数据键，例如 dogbreed。
    • CUSTOM_METADATA_VALUE 是您要与自定义元数据键关联的值，例如 shibainu。

    如需删除自定义元数据条目，请使用以下格式：

    {
  "metadata": {
    "CUSTOM_METADATA_KEY": null
  }
}

    其中：

    • CUSTOM_METADATA_KEY 是您想要删除的自定义元数据的键，例如 dogbreed。

  3. 使用 cURL，通过 PATCH Object 请求调用 JSON API：

    curl -X PATCH --data-binary @JSON_FILE_NAME.json \
  -H "Authorization: Bearer OAUTH2_TOKEN" \
  -H "Content-Type: application/json" \
  "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/o/OBJECT_NAME"

    其中：

    • JSON_FILE_NAME 是您在第 2 步中创建的 JSON 文件的名称。
    • OAUTH2_TOKEN 是您在第 1 步中生成的访问令牌的名称。
    • BUCKET_NAME 是包含您要修改其元数据的对象的存储分区的名称，例如 my-bucket。
    • OBJECT_NAME 是您要修改其元数据的对象的名称，例如 pets/dog.png。

请注意，您还可以使用 UPDATE Object 请求更改对象的元数据。使用此方法时，系统会从对象的元数据中移除请求中未明确指定的所有元数据。

XML API

使用 XML API 时，您只能在写入对象时（例如上传、移动或替换对象时）设置元数据。按照说明（比如上传对象）操作，并遵循以下准则：

  • 将 -H "METADATA_KEY:METADATA_VALUE" 添加到您所设置的每个元数据值的请求标头中，例如 -H "Content-Type:image/png"。

  • 在任何自定义元数据值前面加上 x-goog-meta- 前缀。自定义 "METADATA_KEY:METADATA_VALUE" 的一个示例是 "x-goog-meta-dogbreed:shibainu"。

如需了解详情，请参阅使用 XML 上传对象。

后续步骤