存取公開資料

Cloud Storage 中儲存的部分資料經過設定，因此任何人隨時都能讀取。您可以透過多種方式存取這項公開資料，具體取決於您想如何使用資料。

  1. 取得公開物件的名稱，以及儲存該物件的 bucket。

  2. 使用下列 URI 存取值區中的物件：

    https://storage.googleapis.com/BUCKET_NAME/OBJECT_NAME

舉例來說，Google 公開值區 gcp-public-data-landsat 包含 Landsat 公開資料集。您可以連結至公開分享的物件 LC08/01/001/003/LC08_L1GT_001003_20140812_20170420_01_T2/LC08_L1GT_001003_20140812_20170420_01_T2_B3.TIF，方法是使用下列連結：

https://storage.googleapis.com/gcp-public-data-landsat/LC08/01/001/003/LC08_L1GT_001003_20140812_20170420_01_T2/LC08_L1GT_001003_20140812_20170420_01_T2_B3.TIF

控制台

  1. 取得公開物件的名稱，以及儲存該物件的 bucket。

  2. 使用網路瀏覽器，透過下列 URI 存取物件 (如果尚未登入，系統會要求您登入)：

    https://console.cloud.google.com/storage/browser/_details/BUCKET_NAME/OBJECT_NAME

  3. 如果大眾有權限列出 bucket 的內容，您可以使用下列 URI 列出 bucket 中的所有物件：

    https://console.cloud.google.com/storage/browser/BUCKET_NAME

舉例來說，Google 公開值區 gcp-public-data-landsat 包含 Landsat 公開資料集。您可以透過下列連結存取值區：

https://console.cloud.google.com/storage/browser/gcp-public-data-landsat

指令列

  1. 如果沒有 gcloud CLI，請按照這些操作說明安裝。

    • 安裝 gcloud CLI 時，如果不想驗證，請略過執行 gcloud init 指令的步驟，改為執行下列指令：

      gcloud config set auth/disable_credentials True

  2. 取得公開物件的名稱，以及儲存該物件的 bucket。

  3. 如果列出 bucket 內容的權限已授予公開對象，您可以使用 ls 指令，列出 bucket 中包含的部分或所有物件。

    舉例來說，Google 公開值區 gcp-public-data-landsat 包含 Landsat 公開資料集。您可以使用下列指令，列出前置字串為 LC08/01/001/003/LC 的物件：

    gcloud storage ls --recursive gs://gcp-public-data-landsat/LC08/01/001/003/LC*

  4. 使用 cp 指令，下載 bucket 中包含的特定公開物件。

    舉例來說，下列指令會將檔案從 bucket gcp-public-data-landsat 下載到本機目錄：

    gcloud storage cp gs://gcp-public-data-landsat/LC08/01/001/003/LC08_L1GT_001003_20140812_20170420_01_T2/LC08_L1GT_001003_20140812_20170420_01_T2_B3.TIF .

用戶端程式庫

C++

詳情請參閱 Cloud Storage C++ API 參考文件。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。

namespace gcs = ::google::cloud::storage;
[](std::string const& bucket_name, std::string const& object_name) {
  // Create a client that does not authenticate with the server.
  auto client = gcs::Client{
      google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
          google::cloud::MakeInsecureCredentials())};

  // Read an object, the object must have been made public.
  gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

  int count = 0;
  std::string line;
  while (std::getline(stream, line, '\n')) {
    ++count;
  }
  if (stream.bad()) throw google::cloud::Status(stream.status());
  std::cout << "The object has " << count << " lines\n";
}

C#

詳情請參閱 Cloud Storage C# API 參考文件。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。


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

public class DownloadPublicFileSample
{
    public string DownloadPublicFile(
        string bucketName = "your-bucket-name",
        string objectName = "your-object-name",
        string localPath = "path/to/download/object/to")
    {
        var storage = StorageClient.CreateUnauthenticated();

        using var outputFile = File.OpenWrite(localPath);
        storage.DownloadObject(bucketName, objectName, outputFile);

        Console.WriteLine($"Downloaded public file {objectName} from bucket {bucketName} to {localPath}.");
        return localPath;
    }
}

Go

詳情請參閱 Cloud Storage Go API 參考文件。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。

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

	"cloud.google.com/go/storage"
	"google.golang.org/api/option"
)

// downloadPublicFile downloads a public object.
func downloadPublicFile(w io.Writer, bucket, object string) ([]byte, error) {
	// bucket := "bucket-name"
	// object := "object-name"
	ctx := context.Background()
	// Create a client that does not authenticate with the server.
	client, err := storage.NewClient(ctx, option.WithoutAuthentication())
	if err != nil {
		return nil, fmt.Errorf("storage.NewClient: %w", 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: %w", object, err)
	}
	defer rc.Close()

	data, err := io.ReadAll(rc)
	if err != nil {
		return nil, fmt.Errorf("io.ReadAll: %w", err)
	}
	fmt.Fprintf(w, "Blob %v downloaded.\n", object)
	return data, nil
}

Java

詳情請參閱 Cloud Storage Java API 參考文件。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。


import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.nio.file.Path;

public class DownloadPublicObject {
  public static void downloadPublicObject(
      String bucketName, String publicObjectName, Path destFilePath) {
    // The name of the bucket to access
    // String bucketName = "my-bucket";

    // The name of the remote public file to download
    // String publicObjectName = "publicfile.txt";

    // The path to which the file should be downloaded
    // Path destFilePath = Paths.get("/local/path/to/file.txt");

    // Instantiate an anonymous Google Cloud Storage client, which can only access public files
    Storage storage = StorageOptions.getUnauthenticatedInstance().getService();

    storage.downloadTo(BlobId.of(bucketName, publicObjectName), destFilePath);

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

Node.js

詳情請參閱「Cloud Storage Node.js API 參考文件」。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。

/**
 * 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 srcFilename = '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 downloadPublicFile() {
  const options = {
    destination: destFileName,
  };

  // Download public file.
  await storage.bucket(bucketName).file(srcFileName).download(options);

  console.log(
    `Downloaded public file ${srcFileName} from bucket name ${bucketName} to ${destFileName}`
  );
}

downloadPublicFile().catch(console.error);

Python

詳情請參閱「Cloud Storage Python API 參考文件」。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。

from google.cloud import storage


def download_public_file(bucket_name, source_blob_name, destination_file_name):
    """Downloads a public 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.create_anonymous_client()

    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(source_blob_name)
    blob.download_to_filename(destination_file_name)

    print(
        "Downloaded public blob {} from bucket {} to {}.".format(
            source_blob_name, bucket.name, destination_file_name
        )
    )

Ruby

詳情請參閱 Cloud Storage Ruby API 參考文件。

如要向 Cloud Storage 進行驗證，請設定應用程式預設憑證。詳情請參閱「設定用戶端程式庫的驗證機制」。

def download_public_file bucket_name:, file_name:, local_file_path:
  # The name of the bucket to access
  # bucket_name = "my-bucket"

  # The name of the remote public file to download
  # file_name = "publicfile.txt"

  # 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.anonymous
  bucket  = storage.bucket bucket_name, skip_lookup: true
  file    = bucket.file file_name

  file.download local_file_path

  puts "Downloaded public object #{file.name} from bucket #{bucket} to #{local_file_path}"
end

Rust

use google_cloud_auth::credentials::anonymous;
use google_cloud_storage::client::Storage;

pub async fn sample(bucket: &str, object: &str) -> Result<(), anyhow::Error> {
    let client = Storage::builder()
        .with_credentials(anonymous::Builder::new().build())
        .build()
        .await?;

    // Download the file.
    let mut reader = client
        .read_object(format!("projects/_/buckets/{bucket}"), object)
        .send()
        .await?;

    println!("counting newlines {object} in bucket {bucket}");
    let mut count = 0;
    while let Some(buffer) = reader.next().await.transpose()? {
        count += buffer.into_iter().filter(|c| *c == b'\n').count();
    }
    println!("Public object {object} in bucket {bucket} contains {count} newlines");
    Ok(())
}

後續步驟