const mqtt = require('mqtt');

exports.main = async (event, context) => {
  return new Promise((resolve, reject) => {
    // 连接到 MQTT 服务器
    const client = mqtt.connect('wss://mqtt.example.com:8083/mqtt', {
      username: 'your-username',
      password: 'your-password',
    });

    // 连接成功
    client.on('connect', () => {
      console.log('MQTT 连接成功');
      client.subscribe('test/topic', (err) => {
        if (err) {
          console.error('订阅失败:', err);
          reject(err);
        } else {
          console.log('订阅成功');
        }
      });
    });

    // 接收消息
    client.on('message', (topic, message) => {
      console.log(`收到消息: ${message.toString()}`);
      resolve({
        topic,
        message: message.toString(),
      });
    });

    // 连接失败
    client.on('error', (error) => {
      console.error('MQTT 连接失败:', error);
      reject(error);
    });
  });
};

注意：  需要用return new Promise((resolve, reject) => { 包起来。我没包起来，导致项目中可用，但是云函数中用不了。