下載及匯出檔案

Google Drive API 支援多種下載和匯出動作， 列於下表：

下載內容
使用 files.get 方法搭配 alt=media 網址參數的 Blob 檔案內容。
舊版 Blob 檔案內容，使用 revisions.get 方法搭配 alt=media 網址參數。
在瀏覽器中使用 webContentLink 欄位的 Blob 檔案內容。
匯出
Google Workspace 文件內容，採用應用程式可處理的格式，使用 files.export。
在瀏覽器中使用 exportLinks 欄位傳送的 Google Workspace 文件內容。
透過瀏覽器使用 exportLinks 欄位，在舊版瀏覽器中存取 Google Workspace 文件內容。

請先確認使用者能夠 方法是使用capabilities.canDownload files 資源。

本指南的其餘部分提供了執行這些類型的詳細操作說明 下載及匯出動作

下載 blob 檔案內容

如要下載儲存在雲端硬碟中的 blob 檔案，請使用含有要下載檔案 ID 的 files.get 方法 和 alt=media 網址參數alt=media 網址參數會告訴系統 要求下載內容做為替代回應的伺服器 格式。

alt=media 網址參數是一個系統 參數 且所有 Google REST API 均提供相同格式的檔案如果針對 Drive API，您不需要明確設定這個參數。

以下程式碼範例說明如何使用 files.get 方法下載 連結至 Drive API 用戶端程式庫

Java

drive/snippets/drive_v3/src/main/java/DownloadFile.java
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

/* Class to demonstrate use-case of drive's download file. */
public class DownloadFile {

  /**
   * Download a Document file in PDF format.
   *
   * @param realFileId file ID of any workspace document format file.
   * @return byte array stream if successful, {@code null} otherwise.
   * @throws IOException if service account credentials file not found.
   */
  public static ByteArrayOutputStream downloadFile(String realFileId) throws IOException {
        /* Load pre-authorized user credentials from the environment.
           TODO(developer) - See https://developers.google.com/identity for
          guides on implementing OAuth2 for your application.*/
    GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
        .createScoped(Arrays.asList(DriveScopes.DRIVE_FILE));
    HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(
        credentials);

    // Build a new authorized API client service.
    Drive service = new Drive.Builder(new NetHttpTransport(),
        GsonFactory.getDefaultInstance(),
        requestInitializer)
        .setApplicationName("Drive samples")
        .build();

    try {
      OutputStream outputStream = new ByteArrayOutputStream();

      service.files().get(realFileId)
          .executeMediaAndDownloadTo(outputStream);

      return (ByteArrayOutputStream) outputStream;
    } catch (GoogleJsonResponseException e) {
      // TODO(developer) - handle error appropriately
      System.err.println("Unable to move file: " + e.getDetails());
      throw e;
    }
  }
}

Python

drive/snippets/drive-v3/file_snippet/download_file.py
import io

import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
from googleapiclient.http import MediaIoBaseDownload


def download_file(real_file_id):
  """Downloads a file
  Args:
      real_file_id: ID of the file to download
  Returns : IO object with location.

  Load pre-authorized user credentials from the environment.
  TODO(developer) - See https://developers.google.com/identity
  for guides on implementing OAuth2 for the application.
  """
  creds, _ = google.auth.default()

  try:
    # create drive api client
    service = build("drive", "v3", credentials=creds)

    file_id = real_file_id

    # pylint: disable=maybe-no-member
    request = service.files().get_media(fileId=file_id)
    file = io.BytesIO()
    downloader = MediaIoBaseDownload(file, request)
    done = False
    while done is False:
      status, done = downloader.next_chunk()
      print(f"Download {int(status.progress() * 100)}.")

  except HttpError as error:
    print(f"An error occurred: {error}")
    file = None

  return file.getvalue()


if __name__ == "__main__":
  download_file(real_file_id="1KuPmvGq8yoYgbfW74OENMCB5H0n_2Jm9")

Node.js

drive/snippets/drive_v3/file_snippets/download_file.js
/**
 * Downloads a file
 * @param{string} realFileId file ID
 * @return{obj} file status
 * */
async function downloadFile(realFileId) {
  // Get credentials and build service
  // TODO (developer) - Use appropriate auth mechanism for your app

  const {GoogleAuth} = require('google-auth-library');
  const {google} = require('googleapis');

  const auth = new GoogleAuth({
    scopes: 'https://www.googleapis.com/auth/drive',
  });
  const service = google.drive({version: 'v3', auth});

  fileId = realFileId;
  try {
    const file = await service.files.get({
      fileId: fileId,
      alt: 'media',
    });
    console.log(file.status);
    return file.status;
  } catch (err) {
    // TODO(developer) - Handle error
    throw err;
  }
}

PHP

drive/snippets/drive_v3/src/DriveDownloadFile.php
use Google\Client;
use Google\Service\Drive;
function downloadFile()
 {
    try {

      $client = new Client();
      $client->useApplicationDefaultCredentials();
      $client->addScope(Drive::DRIVE);
      $driveService = new Drive($client);
      $realFileId = readline("Enter File Id: ");
      $fileId = '0BwwA4oUTeiV1UVNwOHItT0xfa2M';
      $fileId = $realFileId;
      $response = $driveService->files->get($fileId, array(
          'alt' => 'media'));
      $content = $response->getBody()->getContents();
      return $content;

    } catch(Exception $e) {
      echo "Error Message: ".$e;
    }

}

.NET

drive/snippets/drive_v3/DriveV3Snippets/DownloadFile.cs
using Google.Apis.Auth.OAuth2;
using Google.Apis.Download;
using Google.Apis.Drive.v3;
using Google.Apis.Services;

namespace DriveV3Snippets
{
    // Class to demonstrate use-case of drive's download file.
    public class DownloadFile
    {
        /// <summary>
        /// Download a Document file in PDF format.
        /// </summary>
        /// <param name="fileId">file ID of any workspace document format file.</param>
        /// <returns>byte array stream if successful, null otherwise.</returns>
        public static MemoryStream DriveDownloadFile(string fileId)
        {
            try
            {
                /* Load pre-authorized user credentials from the environment.
                 TODO(developer) - See https://developers.google.com/identity for 
                 guides on implementing OAuth2 for your application. */
                GoogleCredential credential = GoogleCredential
                    .GetApplicationDefault()
                    .CreateScoped(DriveService.Scope.Drive);

                // Create Drive API service.
                var service = new DriveService(new BaseClientService.Initializer
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "Drive API Snippets"
                });

                var request = service.Files.Get(fileId);
                var stream = new MemoryStream();

                // Add a handler which will be notified on progress changes.
                // It will notify on each chunk download and when the
                // download is completed or failed.
                request.MediaDownloader.ProgressChanged +=
                    progress =>
                    {
                        switch (progress.Status)
                        {
                            case DownloadStatus.Downloading:
                            {
                                Console.WriteLine(progress.BytesDownloaded);
                                break;
                            }
                            case DownloadStatus.Completed:
                            {
                                Console.WriteLine("Download complete.");
                                break;
                            }
                            case DownloadStatus.Failed:
                            {
                                Console.WriteLine("Download failed.");
                                break;
                            }
                        }
                    };
                request.Download(stream);

                return stream;
            }
            catch (Exception e)
            {
                // TODO(developer) - handle error appropriately
                if (e is AggregateException)
                {
                    Console.WriteLine("Credential Not found");
                }
                else
                {
                    throw;
                }
            }
            return null;
        }
    }
}

此程式碼範例使用程式庫方法新增 alt=media 網址參數 指向基礎 HTTP 要求

從應用程式下載檔案的作業範圍，必須允許範圍 可以讀取檔案內容。舉例來說，如果應用程式使用 drive.readonly.metadata 範圍權限不足，無法下載檔案內容。 這個程式碼範例使用了受限制的「雲端硬碟」檔案範圍，方便使用者 查看及管理所有雲端硬碟檔案。如要進一步瞭解 雲端硬碟範圍，請參閱「選擇 Google Drive API」 範圍。

具有編輯權限的使用者可限制唯讀使用者下載 將 copyRequiresWriterPermission 新增至 false。

識別為檔案 濫用 （例如有害軟體），只能由檔案擁有者下載。 而且也必須加入 get 查詢參數 acknowledgeAbuse=true 表示使用者已瞭解下載風險 垃圾軟體或其他不當檔案您的應用程式應具有互動性 在使用查詢參數前發出警告

已下載部分內容

部分下載只涉及下載檔案的特定部分。個人中心 可以使用 byte： 範圍 並加上 Range 標頭。例如：

Range: bytes=500-999

下載較舊版本的 blob 檔案內容

如要下載舊版的 blob 檔案內容，請使用 revisions.get 方法，ID 為 要下載的檔案、修訂版本 ID 以及 alt=media 網址參數。 alt=media 網址參數會告知伺服器系統下載的內容 做為替代回應格式的要求與 files.get 類似， revisions.get 方法也接受選用的查詢參數 acknowledgeAbuse 和 Range 標頭。進一步瞭解下載 修訂版本，請參閱下載及發布檔案 修訂版本。

在瀏覽器中下載 blob 檔案內容

如要下載儲存在雲端硬碟的 blob 檔案內容， 而不是透過 API 使用 webContentLink 欄位， files 資源。如果使用者下載了 檔案存取權、下載檔案的連結及其內容 。您可以將使用者重新導向至這個網址，或提供可點擊的網址 連結。

匯出 Google Workspace 文件內容

如要匯出 Google Workspace 文件位元組內容，請使用 files.export 方法搭配要匯出的檔案 ID 以及正確的 MIME 類型。已匯出 大小上限為 10 MB。

以下程式碼範例說明如何使用 files.export 方法匯出 透過 Drive API 用戶端使用 PDF 格式的 Google Workspace 文件 程式庫：

Java

drive/snippets/drive_v3/src/main/java/ExportPdf.java
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

/* Class to demonstrate use-case of drive's export pdf. */
public class ExportPdf {

  /**
   * Download a Document file in PDF format.
   *
   * @param realFileId file ID of any workspace document format file.
   * @return byte array stream if successful, {@code null} otherwise.
   * @throws IOException if service account credentials file not found.
   */
  public static ByteArrayOutputStream exportPdf(String realFileId) throws IOException {
    // Load pre-authorized user credentials from the environment.
    // TODO(developer) - See https://developers.google.com/identity for
    // guides on implementing OAuth2 for your application.
    GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
        .createScoped(Arrays.asList(DriveScopes.DRIVE_FILE));
    HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(
        credentials);

    // Build a new authorized API client service.
    Drive service = new Drive.Builder(new NetHttpTransport(),
        GsonFactory.getDefaultInstance(),
        requestInitializer)
        .setApplicationName("Drive samples")
        .build();

    OutputStream outputStream = new ByteArrayOutputStream();
    try {
      service.files().export(realFileId, "application/pdf")
          .executeMediaAndDownloadTo(outputStream);

      return (ByteArrayOutputStream) outputStream;
    } catch (GoogleJsonResponseException e) {
      // TODO(developer) - handle error appropriately
      System.err.println("Unable to export file: " + e.getDetails());
      throw e;
    }
  }
}

Python

drive/snippets/drive-v3/file_snippet/export_pdf.py
import io

import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
from googleapiclient.http import MediaIoBaseDownload


def export_pdf(real_file_id):
  """Download a Document file in PDF format.
  Args:
      real_file_id : file ID of any workspace document format file
  Returns : IO object with location

  Load pre-authorized user credentials from the environment.
  TODO(developer) - See https://developers.google.com/identity
  for guides on implementing OAuth2 for the application.
  """
  creds, _ = google.auth.default()

  try:
    # create drive api client
    service = build("drive", "v3", credentials=creds)

    file_id = real_file_id

    # pylint: disable=maybe-no-member
    request = service.files().export_media(
        fileId=file_id, mimeType="application/pdf"
    )
    file = io.BytesIO()
    downloader = MediaIoBaseDownload(file, request)
    done = False
    while done is False:
      status, done = downloader.next_chunk()
      print(f"Download {int(status.progress() * 100)}.")

  except HttpError as error:
    print(f"An error occurred: {error}")
    file = None

  return file.getvalue()


if __name__ == "__main__":
  export_pdf(real_file_id="1zbp8wAyuImX91Jt9mI-CAX_1TqkBLDEDcr2WeXBbKUY")

Node.js

drive/snippets/drive_v3/file_snippets/export_pdf.js
/**
 * Download a Document file in PDF format
 * @param{string} fileId file ID
 * @return{obj} file status
 * */
async function exportPdf(fileId) {
  const {GoogleAuth} = require('google-auth-library');
  const {google} = require('googleapis');

  // Get credentials and build service
  // TODO (developer) - Use appropriate auth mechanism for your app
  const auth = new GoogleAuth({
    scopes: 'https://www.googleapis.com/auth/drive',
  });
  const service = google.drive({version: 'v3', auth});

  try {
    const result = await service.files.export({
      fileId: fileId,
      mimeType: 'application/pdf',
    });
    console.log(result.status);
    return result;
  } catch (err) {
    // TODO(developer) - Handle error
    throw err;
  }
}

PHP

drive/snippets/drive_v3/src/DriveExportPdf.php
use Google\Client;
use Google\Service\Drive;
function exportPdf()
{
    try {
        $client = new Client();
        $client->useApplicationDefaultCredentials();
        $client->addScope(Drive::DRIVE);
        $driveService = new Drive($client);
        $realFileId = readline("Enter File Id: ");
        $fileId = '1ZdR3L3qP4Bkq8noWLJHSr_iBau0DNT4Kli4SxNc2YEo';
        $fileId = $realFileId;
        $response = $driveService->files->export($fileId, 'application/pdf', array(
            'alt' => 'media'));
        $content = $response->getBody()->getContents();
        return $content;

    }  catch(Exception $e) {
         echo "Error Message: ".$e;
    }

}

.NET

drive/snippets/drive_v3/DriveV3Snippets/ExportPdf.cs
using Google.Apis.Auth.OAuth2;
using Google.Apis.Download;
using Google.Apis.Drive.v3;
using Google.Apis.Services;

namespace DriveV3Snippets
{
    // Class to demonstrate use of Drive export pdf
    public class ExportPdf
    {
        /// <summary>
        /// Download a Document file in PDF format.
        /// </summary>
        /// <param name="fileId">Id of the file.</param>
        /// <returns>Byte array stream if successful, null otherwise</returns>
        public static MemoryStream DriveExportPdf(string fileId)
        {
            try
            {
                /* Load pre-authorized user credentials from the environment.
                 TODO(developer) - See https://developers.google.com/identity for 
                 guides on implementing OAuth2 for your application. */
                GoogleCredential credential = GoogleCredential.GetApplicationDefault()
                    .CreateScoped(DriveService.Scope.Drive);

                // Create Drive API service.
                var service = new DriveService(new BaseClientService.Initializer
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "Drive API Snippets"
                });

                var request = service.Files.Export(fileId, "application/pdf");
                var stream = new MemoryStream();
                // Add a handler which will be notified on progress changes.
                // It will notify on each chunk download and when the
                // download is completed or failed.
                request.MediaDownloader.ProgressChanged +=
                    progress =>
                    {
                        switch (progress.Status)
                        {
                            case DownloadStatus.Downloading:
                            {
                                Console.WriteLine(progress.BytesDownloaded);
                                break;
                            }
                            case DownloadStatus.Completed:
                            {
                                Console.WriteLine("Download complete.");
                                break;
                            }
                            case DownloadStatus.Failed:
                            {
                                Console.WriteLine("Download failed.");
                                break;
                            }
                        }
                    };
                request.Download(stream);
                return stream;
            }
            catch (Exception e)
            {
                // TODO(developer) - handle error appropriately
                if (e is AggregateException)
                {
                    Console.WriteLine("Credential Not found");
                }
                else
                {
                    throw;
                }
            }
            return null;
        }
    }
}

這個程式碼範例使用了受限制的 drive 範圍，可讓使用者查看並 管理所有雲端硬碟檔案如要進一步瞭解 雲端硬碟範圍，請參閱「選擇 Google Drive API」 範圍。

程式碼範例也會將匯出的 MIME 類型宣告為 application/pdf。換 各種 Google Workspace 支援匯出 MIME 類型的完整清單 文件，請參閱「匯出 Google Workspace 的 MIME 類型」 文件。

在瀏覽器中匯出 Google Workspace 文件內容

如要在瀏覽器中匯出 Google Workspace 文件內容，請使用 exportLinks 欄位， files 資源。視文件內容而定 類型，下載檔案的連結，以及每個 MIME 都會傳回其內容 可用的類型。您可以將使用者重新導向至特定網址，或以網址的形式提供 可點擊的連結。

在瀏覽器中將 Google Workspace 文件內容匯出到較舊版本

如何將 Google Workspace 文件內容匯出至 瀏覽器，請使用 revisions.get 方法 附加下載檔案的 ID 和修訂版本 ID。如果使用者 檔案的下載權限、下載檔案的連結及其內容 。您可以將使用者重新導向至這個網址，或提供可點擊的網址 連結。