下载对象

本页面介绍如何从 Cloud Storage 中的存储分区下载对象。如需查看概念性概览，请参阅上传和下载。

控制台

  1. 在 Google Cloud Console 中打开 Cloud Storage 浏览器。
    打开 Cloud Storage 浏览器

  2. 在存储分区列表中，找到包含要下载的对象的存储分区，并点击其名称。

    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. 选择下载。

请参阅问题排查，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。

gsutil

使用 gsutil cp 命令：

gsutil cp gs://BUCKET_NAME/OBJECT_NAME SAVE_TO_LOCATION

其中：

  • BUCKET_NAME 是包含要下载的对象的存储分区名称，例如 my-bucket。

  • OBJECT_NAME 是要下载的对象的名称，例如 pets/dog.png。

  • SAVE_TO_LOCATION 是保存对象的本地路径，例如 Desktop/Images。

如果成功，则响应类似如下示例：

Operation completed over 1 objects/58.8 KiB.

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;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name) {
  gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

  int count = 0;
  std::string line;
  while (std::getline(stream, line, '\n')) {
    ++count;
  }

  std::cout << "The object has " << count << " lines\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;
using System.IO;

public class DownloadFileSample
{
    public void DownloadFile(
        string bucketName = "your-unique-bucket-name",
        string objectName = "my-file-name",
        string localPath = "my-local-path/my-file-name")
    {
        var storage = StorageClient.Create();
        using var outputFile = File.OpenWrite(localPath);
        storage.DownloadObject(bucketName, objectName, outputFile);
        Console.WriteLine($"Downloaded {objectName} to {localPath}.");
    }
}

Go

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

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"time"

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

// downloadFile downloads an object.
func downloadFile(w io.Writer, bucket, object string) ([]byte, 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*50)
	defer cancel()

	rc, err := client.Bucket(bucket).Object(object).NewReader(ctx)
	if err != nil {
		return nil, fmt.Errorf("Object(%q).NewReader: %v", object, err)
	}
	defer rc.Close()

	data, err := ioutil.ReadAll(rc)
	if err != nil {
		return nil, fmt.Errorf("ioutil.ReadAll: %v", err)
	}
	fmt.Fprintf(w, "Blob %v downloaded.\n", object)
	return data, 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.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.nio.file.Paths;

public class DownloadObject {
  public static void downloadObject(
      String projectId, String bucketName, String objectName, String destFilePath) {
    // 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";

    // The path to which the file should be downloaded
    // String destFilePath = "/local/path/to/file.txt";

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

    Blob blob = storage.get(BlobId.of(bucketName, objectName));
    blob.downloadTo(Paths.get(destFilePath));

    System.out.println(
        "Downloaded object "
            + objectName
            + " from bucket name "
            + bucketName
            + " to "
            + destFilePath);
  }
}

Node.js

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

您可以使用 File.download() 或 File.createReadStream() 方法下载对象。
/**
 * 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';

// The path to which the file should be downloaded
// const destFileName = '/local/path/to/file.txt';

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

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

async function downloadFile() {
  const options = {
    destination: destFileName,
  };

  // Downloads the file
  await storage.bucket(bucketName).file(fileName).download(options);

  console.log(
    `gs://${bucketName}/${fileName} downloaded to ${destFileName}.`
  );
}

downloadFile().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;

/**
 * Download an object from Cloud Storage and save it as a local file.
 *
 * @param string $bucketName the name of your Google Cloud bucket.
 * @param string $objectName the name of your Google Cloud object.
 * @param string $destination the local destination to save the encrypted object.
 *
 * @return void
 */
function download_object($bucketName, $objectName, $destination)
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $object->downloadToFile($destination);
    printf('Downloaded gs://%s/%s to %s' . PHP_EOL,
        $bucketName, $objectName, basename($destination));
}

Python

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

from google.cloud import storage

def download_blob(bucket_name, source_blob_name, destination_file_name):
    """Downloads a blob from the bucket."""
    # bucket_name = "your-bucket-name"
    # source_blob_name = "storage-object-name"
    # destination_file_name = "local/path/to/file"

    storage_client = storage.Client()

    bucket = storage_client.bucket(bucket_name)

    # Construct a client side representation of a blob.
    # Note `Bucket.blob` differs from `Bucket.get_blob` as it doesn't retrieve
    # any content from Google Cloud Storage. As we don't need additional data,
    # using `Bucket.blob` is preferred here.
    blob = bucket.blob(source_blob_name)
    blob.download_to_filename(destination_file_name)

    print(
        "Blob {} downloaded to {}.".format(
            source_blob_name, destination_file_name
        )
    )

Ruby

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

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

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

  # The path to which the file should be downloaded
  # local_file_path = "/local/path/to/file.txt"

  require "google/cloud/storage"

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

  file.download local_file_path

  puts "Downloaded #{file.name} to #{local_file_path}"
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" \
  -o "SAVE_TO_LOCATION" \
  "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/o/OBJECT_NAME?alt=media"

    其中：

    • OAUTH2_TOKEN 是您在第 1 步中生成的访问令牌。
    • SAVE_TO_LOCATION 是您想要将对象保存到的位置的路径，例如 Desktop/dog.png。
    • BUCKET_NAME 是包含要下载的对象的存储分区名称，例如 my-bucket。
    • OBJECT_NAME 是要下载的对象的名称，例如 pets/dog.png。如需了解如何对对象名称进行网址编码以使其具备路径安全性，请参阅对 URI 路径部分进行编码。

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 GET Object 请求调用 XML API：

    curl -X GET \
  -H "Authorization: Bearer OAUTH2_TOKEN" \
  -o "SAVE_TO_LOCATION" \
  "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。
    • SAVE_TO_LOCATION 是您想要将对象保存到的位置的路径，例如 Desktop/dog.png。
    • BUCKET_NAME 是包含要下载的对象的存储分区名称，例如 my-bucket。
    • OBJECT_NAME 是要下载的对象的名称，例如 pets/dog.png。

要轻松下载存储分区或子目录中的所有对象，请使用 gsutil cp 命令。

后续步骤

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