如何使用gmail api获取特定用户的第一条消息

pip install --upgrade google-api-python-client google-auth-httplib2 google-auth-oauthlib

import os
import base64
import json
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from googleapiclient.discovery import build

# 如果修改这些 SCOPES，删除文件 token.json。
SCOPES = ['https://www.googleapis.com/auth/gmail.readonly']

def main():
    """Shows basic usage of the Gmail API.
    Lists the user's first message.
    """
    creds = None
    # token.json 存储用户的访问和刷新令牌，首次运行时会创建。
    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)
    # 如果没有有效的凭据，允许用户登录。
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file(
                'credentials.json', SCOPES)
            creds = flow.run_local_server(port=0)
        # 保存凭据以供下次使用
        with open('token.json', 'w') as token:
            token.write(creds.to_json())

    # 调用 Gmail API
    service = build('gmail', 'v1', credentials=creds)

    # 获取用户的邮件列表
    results = service.users().messages().list(userId='me', maxResults=1, orderBy='ascending').execute()
    messages = results.get('messages', [])

    if not messages:
        print('没有找到消息。')
    else:
        # 获取第一条消息的 ID
        first_message_id = messages[0]['id']
        # 获取消息详细信息
        message = service.users().messages().get(userId='me', id=first_message_id).execute()
        
        # 打印消息主题
        for header in message['payload']['headers']:
            if header['name'] == 'Subject':
                print('第一条消息的主题:', header['value'])
        
        # 打印消息内容（可选）
        if 'data' in message['payload']['parts'][0]['body']:
            data = message['payload']['parts'][0]['body']['data']
            decoded_data = base64.urlsafe_b64decode(data).decode('utf-8')
            print('消息内容:', decoded_data)

if __name__ == '__main__':
    main()