问如何在nodejs控制器中添加中间件？

EN

'use strict';

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

const signupController = require('../controller/signup.controller');
const signinController = require('../controller/signin.controller');
const userListController = require('../controller/userList.controller');
const productController = require('../controller/product.controller');

const passport = require('passport');
require('../config/passport')(passport);


router.get('/users', passport.authenticate('jwt', {session: false}), userListController.getUserList);

router.post('/product', productController.addProduct)

router.post('/user/signup', signupController.Signup);

router.post('/user/signin', signinController.Signin);


module.exports = router;

'use strict';
var mongoose = require('mongoose');
var Product = require('../model/product.model');
var multer = require('multer');
var path = require('path');


// File storage configuration
const storage = multer.diskStorage({
    destination: (req, file, cb) => {
        cb(null, '...store some where in filesystem...');
    }
});

// File filter configuration
const fileFilter = (req, file, cb) => {
    if (path.extname(file) === '.gpg') {
        cb(null, true);
    } else {
        cb(null, false);
    }
};

// File upload configuration
const upload = multer({
    storage: storage,
    limits: {
        fileSize: 1024 * 1024 * 5
    },
    //fileFilter: fileFilter
});


// Loader module
exports.addProduct = (req, res, next) => {
    console.log(req.file);
    ...    
}