如何通过路由器、控制器和index.js在节点服务器中使用socket.io？

const express = require('express');
const router = express.Router();

router.get('/chat', (req, res) => {
  res.sendFile(__dirname + '/chat.html');
});

const io = require('socket.io')(server);

io.on('connection', (socket) => {
  console.log('A user connected');

  socket.on('chat message', (msg) => {
    console.log('Message: ' + msg);
    io.emit('chat message', msg);
  });

  socket.on('disconnect', () => {
    console.log('A user disconnected');
  });
});

const express = require('express');
const http = require('http');
const socketIO = require('socket.io');
const router = require('./router');
const controller = require('./controller');

const app = express();
const server = http.createServer(app);
const io = socketIO(server);

app.use('/', router);

controller(io);

const port = 3000;
server.listen(port, () => {
  console.log('Server is running on port ' + port);
});