如何使用 Flutter 将文件上传到 Google Drive？

Question

我正在制作一个 Flutter 移动应用程序，并尝试将相机拍摄的图像保存到特定的 Google 驱动器帐户进行存储。我已从我的 Google 帐户获取服务帐户 JSON 文件进行身份验证。

这是我正在使用的代码：

import 'dart:io' as io;
import 'package:googleapis/drive/v3.dart' as ga;
import 'package:googleapis_auth/auth.dart';
import 'package:googleapis_auth/auth_io.dart';

uploadFileToGoogleDrive(io.File fileToUpload) async {

  // send authorization to access Google Drive
  // from https://pub.dev/packages/googleapis_auth

  ServiceAccountCredentials accountCredentials = new ServiceAccountCredentials.fromJson({
//my service account JSON information goes here
  });
  List<String> scopes = [ga.DriveApi.DriveFileScope, ga.DriveApi.DriveScope];


 
    try {
      // authenticates with Google Drive with our service account credentials
      AuthClient client = await clientViaServiceAccount(
          accountCredentials, scopes);

      ga.DriveApi drive = ga.DriveApi(client);
      ga.File file = ga.File(); // create new file record to upload to Drive
      try {
        file.name = 'image.jpg';
        
        ga.File response = await drive.files.create(file, uploadMedia: ga.Media(
            fileToUpload.openRead(), fileToUpload.lengthSync()));
   
        print('uploaded with a file size of: ${response.size}');
      } on Exception catch (e) {
        print('upload error: $e');
      }
      client.close();
    } on Exception catch (e) {
      print('credentials error: $e');
    }
  
}

我上传的文件大小为24095。没有返回任何错误消息。返回的“响应”有一个 Google 云端硬盘文件 ID，但大小为空，从网络登录时我无法在 Google 云端硬盘中上传文件。使用 Google Drive API 上传此文件的正确方法是什么？

Answer 1

这很容易，但您必须完成一系列步骤才能完成。

1. 启用 Google Drive API

单击谷歌控制台的链接： https://console.developers.google.com/apis/library? project=diary-app-339509

• 创建一个新项目并在该项目上启用 Drive API。
• 为 Android 和 IOS 创建 OAuth 客户端 ID
• 您必须填写大量详细信息才能创建它，通读该页面并填写它。
• 复制客户端 ID 以供将来使用

创建项目并启用API

创建 OAuth 客户端 ID

填写表格以创建 OAuth 客户端 ID

2. 使项目可供外部使用。

用于测试添加测试用户电子邮件地址

现在是关于 flutter 的编码部分

3.将以下包添加到pubspec.yaml中

  googleapis: ^7.0.0
  googleapis_auth: ^1.3.0
  flutter_secure_storage: ^5.0.2
  url_launcher: ^6.0.0-nullsafety

4. 从 google 获取身份验证并存储身份验证详细信息以供将来的身份验证

使用以下类来存储身份验证详细信息

import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:googleapis_auth/auth_io.dart';

class SecureStorage {
  final storage = FlutterSecureStorage();

  //Save Credentials
  Future saveCredentials(AccessToken token, String refreshToken) async {
    print(token.expiry.toIso8601String());
    await storage.write(key: "type", value: token.type);
    await storage.write(key: "data", value: token.data);
    await storage.write(key: "expiry", value: token.expiry.toString());
    await storage.write(key: "refreshToken", value: refreshToken);
  }

  //Get Saved Credentials
  Future<Map<String, dynamic>?> getCredentials() async {
    var result = await storage.readAll();
    if (result.isEmpty) return null;
    return result;
  }

  //Clear Saved Credentials
  Future clear() {
    return storage.deleteAll();
  }
}

5.最后使用此类将文件保存到云端硬盘

import 'dart:io';
import 'package:googleapis/drive/v3.dart' as ga;
import 'package:googleapis_auth/auth_io.dart';
import 'package:http/http.dart' as http;
import 'package:path/path.dart' as p;
import 'package:personal_diary/app/utils/secure_storage.dart';
import 'package:url_launcher/url_launcher.dart';

const _clientId = "YOUR CLIENT ID FROM GOOGLE CONSOLE";
const _scopes = ['https://www.googleapis.com/auth/drive.file'];

class GoogleDrive {
  final storage = SecureStorage();
  //Get Authenticated Http Client
  Future<http.Client> getHttpClient() async {
    //Get Credentials
    var credentials = await storage.getCredentials();
    if (credentials == null) {
      //Needs user authentication
      var authClient = await clientViaUserConsent(
          ClientId(_clientId),_scopes, (url) {
        //Open Url in Browser
        launch(url);
      });
      //Save Credentials
      await storage.saveCredentials(authClient.credentials.accessToken,
          authClient.credentials.refreshToken!);
      return authClient;
    } else {
      print(credentials["expiry"]);
      //Already authenticated
      return authenticatedClient(
          http.Client(),
          AccessCredentials(
              AccessToken(credentials["type"], credentials["data"],
                  DateTime.tryParse(credentials["expiry"])!),
              credentials["refreshToken"],
              _scopes));
    }
  }

// check if the directory forlder is already available in drive , if available return its id
// if not available create a folder in drive and return id
//   if not able to create id then it means user authetication has failed
  Future<String?> _getFolderId(ga.DriveApi driveApi) async {
    final mimeType = "application/vnd.google-apps.folder";
    String folderName = "personalDiaryBackup";

    try {
      final found = await driveApi.files.list(
        q: "mimeType = '$mimeType' and name = '$folderName'",
        $fields: "files(id, name)",
      );
      final files = found.files;
      if (files == null) {
        print("Sign-in first Error");
        return null;
      }

      // The folder already exists
      if (files.isNotEmpty) {
        return files.first.id;
      }

      // Create a folder
      ga.File folder = ga.File();
      folder.name = folderName;
      folder.mimeType = mimeType;
      final folderCreation = await driveApi.files.create(folder);
      print("Folder ID: ${folderCreation.id}");

      return folderCreation.id;
    } catch (e) {
      print(e);
      return null;
    }
  }

  
  uploadFileToGoogleDrive(File file) async {
    var client = await getHttpClient();
    var drive = ga.DriveApi(client);
    String? folderId =  await _getFolderId(drive);
    if(folderId == null){
      print("Sign-in first Error");
    }else {
      ga.File fileToUpload = ga.File();
      fileToUpload.parents = [folderId];
      fileToUpload.name = p.basename(file.absolute.path);
      var response = await drive.files.create(
        fileToUpload,
        uploadMedia: ga.Media(file.openRead(), file.lengthSync()),
      );
      print(response);
    }

  }




}

Answer 2

结果除了启用 API 和创建服务帐户之外，我还需要使用 JSON 中的服务帐户电子邮件地址共享我想要上传到的文件夹。