如何在通过Dialogflow使用Fulfillment时播放音频文件

const express = require('express');
const app = express();

app.post('/webhook', (req, res) => {
  const intent = req.body.queryResult.intent.displayName;
  
  if (intent === 'PlayAudioIntent') {
    // 播放音频文件的逻辑
    const audioUrl = 'https://example.com/audio.mp3';
    const response = {
      fulfillmentText: '正在播放音频文件，请稍候。',
      fulfillmentMessages: [
        {
          platform: 'ACTIONS_ON_GOOGLE',
          simpleResponses: {
            simpleResponses: [
              {
                textToSpeech: '正在播放音频文件，请稍候。'
              }
            ]
          }
        },
        {
          platform: 'ACTIONS_ON_GOOGLE',
          mediaContent: {
            mediaType: 'AUDIO',
            mediaObjects: [
              {
                name: '音频文件',
                description: '描述音频文件',
                largeImage: {
                  url: 'https://example.com/audio_image.png',
                  accessibilityText: '音频文件封面图'
                },
                contentUrl: audioUrl
              }
            ]
          }
        }
      ]
    };
    
    res.json(response);
  }
});

app.listen(3000, () => {
  console.log('Fulfillment服务已启动，监听端口3000');
});