我有一个桌面应用程序，使用GMAIL API通过REST接口读取邮件。我想使用服务帐户来下载邮件，以便我们可以使用域设置而无需用户交互。我成功地能够创建Gmail服务实例，但是当我尝试访问任何Gmail API方法（如获取邮件列表或其他任何方法）时，我会收到一个异常，该异常显示：
Google.Apis.Auth.OAuth2.Responses.TokenResponseException： Error：“access_denied”，Description：“Requested client not authorized。”
我已完成开发者控制台上的所有设置，并将范围添加到我的gapps域。
Gmail API支持服务帐户吗？使用相同的设置和服务帐户，我能够使用Drive服务和API获得Google Drive中的所有文件列表。
我使用以下的C#代码来从服务账户访问Gmail
String serviceAccountEmail =
"999999999-9nqenknknknpmdvif7onn2kvusnqct2c@developer.gserviceaccount.com";
var certificate = new X509Certificate2(
AppDomain.CurrentDomain.BaseDirectory +
"certs//fe433c710f4980a8cc3dda83e54cf7c3bb242a46-privatekey.p12",
"notasecret",
X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
string userEmail = "user@domainhere.com.au";
ServiceAccountCredential credential = new ServiceAccountCredential(
new ServiceAccountCredential.Initializer(serviceAccountEmail)
{
User = userEmail,
Scopes = new[] { "https://mail.google.com/" }
}.FromCertificate(certificate)
);
if (credential.RequestAccessTokenAsync(CancellationToken.None).Result)
{
GmailService gs = new GmailService(
new Google.Apis.Services.BaseClientService.Initializer()
{
ApplicationName = "iLink",
HttpClientInitializer = credential
}
);
UsersResource.MessagesResource.GetRequest gr =
gs.Users.Messages.Get(userEmail, msgId);
gr.Format = UsersResource.MessagesResource.GetRequest.FormatEnum.Raw;
Message m = gr.Execute();
if (gr.Format == UsersResource.MessagesResource.GetRequest.FormatEnum.Raw)
{
byte[] decodedByte = FromBase64ForUrlString(m.Raw);
string base64Encoded = Convert.ToString(decodedByte);
MailMessage msg = new MailMessage();
msg.LoadMessage(decodedByte);
}
}
这里是一些Python 3.7的代码：
from google.oauth2 import service_account
from googleapiclient.discovery import build
def setup_credentials():
key_path = 'gmailsignatureproject-zzz.json'
API_scopes =['https://www.googleapis.com/auth/gmail.settings.basic',
'https://www.googleapis.com/auth/gmail.settings.sharing']
credentials = service_account.Credentials.from_service_account_file(key_path,scopes=API_scopes)
return credentials
def test_setup_credentials():
credentials = setup_credentials()
assert credentials
def test_fetch_user_info():
credentials = setup_credentials()
credentials_delegated = credentials.with_subject("tim@vci.com.au")
gmail_service = build("gmail","v1",credentials=credentials_delegated)
addresses = gmail_service.users().settings().sendAs().list(userId='me').execute()
assert gmail_service
对于C# Gmail API v1，您可以使用以下代码获取Gmail服务。使用Gmail服务读取电子邮件。一旦在Google控制台网站上创建服务帐户，就可以下载以json格式的密钥文件。假设文件名为“service.json”。
public static GoogleCredential GetCredenetial(string serviceAccountCredentialJsonFilePath)
{
GoogleCredential credential;
using (var stream = new FileStream(serviceAccountCredentialJsonFilePath, FileMode.Open, FileAccess.Read))
{
credential = GoogleCredential.FromStream(stream)
.CreateScoped(new[] {GmailService.Scope.GmailReadonly})
.CreateWithUser(**impersonateEmail@email.com**);
}
return credential;
}
public static GmailService GetGmailService(GoogleCredential credential)
{
return new GmailService(new BaseClientService.Initializer()
{
HttpClientInitializer = credential,
ApplicationName = "Automation App",
});
}
// how to use
public static void main()
{
var credential = GetCredenetial("service.json");
var gmailService = GetGmailService(credential);
// you can use gmail service to retrieve emails.
var mMailListRequest = gmailService.Users.Messages.List("me");
mMailListRequest.LabelIds = "INBOX";
var mailListResponse = mMailListRequest.Execute();
}
Google.Apis.Auth.OAuth2.Responses.TokenResponseException: 'Error:"unauthorized_client", Description:"Client is unauthorized to retrieve access tokens using this method, or client not authorized for any of the scopes requested.", Uri:""'。我该如何为服务帐户添加权限？ - Tono Namhttps://www.googleapis.com/auth/gmail.readonly。您可以从此处获取范围列表。 - Circuit Breakerhttps://developers.google.com/gmail/api/
通过模拟服务帐户进行访问（服务帐户像特定用户从您的域一样访问API）。
在此处查看详细信息：https://developers.google.com/identity/protocols/OAuth2ServiceAccount
以下是Dartlang中相关的代码：
import 'package:googleapis_auth/auth_io.dart' as auth;
import 'package:googleapis/gmail/v1.dart' as gmail;
import 'package:http/http.dart' as http;
///credentials created with service_account here https://console.developers.google.com/apis/credentials/?project=YOUR_PROJECT_ID
final String creds = r'''
{
"private_key_id": "FILL_private_key_id",
"private_key": "FILL_private_key",
"client_email": "FILL_service_account_email",
"client_id": "FILL_client_id",
"type": "service_account"
}''';
Future<http.Client> createImpersonatedClient(String impersonatedUserEmail, List scopes) async {
var impersonatedCredentials = new auth.ServiceAccountCredentials.fromJson(creds,impersonatedUser: impersonatedUserEmail);
return auth.clientViaServiceAccount(impersonatedCredentials , scopes);
}
getUserEmails(String userEmail) async { //userEmail from YOUR_DOMAIN.COM
var client = await createImpersonatedClient(userEmail, [gmail.GmailApi.MailGoogleComScope]);
var gmailApi = new gmail.GmailApi(client);
return gmailApi.users.messages.list(userEmail, maxResults: 5);
}