【Python】Gmail APIを使ってメールを受信する方法

gmailclient.py

# coding: utf-8

from __future__ import print_function
import httplib2
import os
import base64
import email

from apiclient import discovery, errors
import oauth2client
from oauth2client import client
from oauth2client import tools

try:
    import argparse
    flags = argparse.ArgumentParser(parents=[tools.argparser]).parse_args()
except ImportError:
    flags = None


class GmailClient(object):
    
    SCOPES = 'https://mail.google.com/'
    CLIENT_SECRET_FILE = 'client_secret.json'
    APPLICATION_NAME = 'Gmail Client'
    
    def __init__(self, **kwargs):
        if "user_id" in kwargs:
            self.user_id = user_id
        else:
            self.user_id = "me"

        credentials = self.credentials()
        http = credentials.authorize(httplib2.Http())
        self.service = discovery.build('gmail', 'v1', http=http)

    # Gmailの認証処理
    def credentials(self):
        home_dir = os.path.expanduser('~')
        credential_dir = os.path.join(home_dir, '.credentials')
        if not os.path.exists(credential_dir):
            os.makedirs(credential_dir)
        
        credential_path = os.path.join(credential_dir,
            'gmail-python-quickstart.json')

        store = oauth2client.file.Storage(credential_path)
        credentials = store.get()
        
        if not credentials or credentials.invalid:
            flow = client.flow_from_clientsecrets(self.CLIENT_SECRET_FILE, self.SCOPES)
            flow.user_agent = self.APPLICATION_NAME
            if flags:
                credentials = tools.run_flow(flow, store, flags)
            else: # Needed only for compatibility with Python 2.6
                credentials = tools.run(flow, store)
            print('Storing credentials to ' + credential_path)
        
        return credentials

    # メールリストを取得
    def get_messages(self, q=""):
        try:
            results = self.service.users().messages().list(userId=self.user_id, q=q).execute()
            for msg in results.get("messages", []):
                message = self.service.users().messages().get(userId=self.user_id, id=msg["id"], format='raw').execute()
                msg_str = base64.urlsafe_b64decode(message['raw']).decode("utf-8")
                self.msg = email.message_from_string(msg_str)
                yield self
        except errors.HttpError as error:
            raise("An error occurred: %s" % error)

    # 件名を取得
    @property
    def subject(self):
        subjects = email.header.decode_header(self.msg.get("Subject"))
        for subject in subjects:
            if isinstance(subject[0], bytes) and subject[1] is not None:
                return subject[0].decode(subject[1])
            else:
                return subject[0].decode()

    # 本文を取得
    @property
    def body(self):
        if self.msg.is_multipart():
            for payload in self.msg.get_payload():
                if payload.get_content_type() == "text/plain":
                    charset = self.msg.get_param("charset")
                    if charset is None:
                        return payload.get_payload(decode=True).decode("iso-2022-jp")
                    else:
                        return payload.get_payload(decode=True).decode(charset)
        else:
            charset = self.msg.get_param("charset")
            return self.msg.get_payload(decode=True).decode(charset)

if __name__ == '__main__':
    Gmail = GmailClient()
    messages = Gmail.get_messages()

    if not messages:
        print('No messages found.')
    else:
        for message in messages:
            print(message.subject)
            print(message.body)