如何在Node.js中使用Gmail API发送带有附件的电子邮件？

npm install googleapis google-auth-library nodemailer

{
  "installed": {
    "client_id": "YOUR_CLIENT_ID",
    "project_id": "YOUR_PROJECT_ID",
    "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    "token_uri": "https://accounts.google.com/o/oauth2/token",
    "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    "client_secret": "YOUR_CLIENT_SECRET",
    "redirect_uris": ["urn:ietf:wg:oauth:2.0:oob", "http://localhost"]
  }
}

const fs = require('fs');
const readline = require('readline');
const { google } = require('googleapis');
const { OAuth2Client } = require('google-auth-library');
const nodemailer = require('nodemailer');

// 读取凭据文件
const credentials = require('./credentials.json');

// 定义要发送的邮件内容
const emailContent = {
  to: 'recipient@example.com',
  subject: '邮件主题',
  text: '邮件正文',
  attachments: [
    {
      filename: '附件文件名',
      path: '附件文件路径'
    }
  ]
};

// 创建OAuth 2.0客户端
const oAuth2Client = new OAuth2Client(
  credentials.installed.client_id,
  credentials.installed.client_secret,
  credentials.installed.redirect_uris[0]
);

// 获取访问令牌
async function getAccessToken() {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: ['https://www.googleapis.com/auth/gmail.send']
  });

  console.log('请访问以下URL并授权：\n', authUrl);

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  });

  return new Promise((resolve, reject) => {
    rl.question('请输入授权码：', (code) => {
      rl.close();
      oAuth2Client.getToken(code, (err, token) => {
        if (err) {
          reject(err);
        } else {
          resolve(token);
        }
      });
    });
  });
}

// 发送邮件
async function sendEmail(auth) {
  const transporter = nodemailer.createTransport({
    service: 'gmail',
    auth: {
      type: 'OAuth2',
      user: 'your.email@gmail.com',
      clientId: credentials.installed.client_id,
      clientSecret: credentials.installed.client_secret,
      refreshToken: auth.refresh_token,
      accessToken: auth.access_token
    }
  });

  const mailOptions = {
    from: 'your.email@gmail.com',
    ...emailContent
  };

  transporter.sendMail(mailOptions, (err, info) => {
    if (err) {
      console.error('发送邮件时出错：', err);
    } else {
      console.log('邮件已发送：', info.response);
    }
  });
}

// 主函数
async function main() {
  try {
    const token = await getAccessToken();
    oAuth2Client.setCredentials(token);
    sendEmail(token);
  } catch (err) {
    console.error('发生错误：', err);
  }
}

// 执行主函数
main();

node sendEmail.js