分层标准
从本章起，正式进入企业级 Web 服务器核心内容。通常，一块残缺的业务逻辑是由视图层、管制层、服务层、模型层独特定义与实现的，如下图：
从上至下，抽象层次逐步加深。从下至上，业务细节逐步清晰。视图层属于 Web 前端内容，本文采纳 JavaScript Modules 进行演示。
本章着重说说管制层与服务层，对业务逻辑外围局部进行开展。
写一个简易版的商铺治理
间接从上一章已实现的工程 host1-tech/nodejs-server-examples - 00-static 开始着手，先编写服务层内容：
$ mkdir src/services # 新建 src/services 目录寄存服务层逻辑$ tree -L 2 -I node_modules # 展现除了 node_modules 之外的目录内容构造.├── Dockerfile├── package.json├── public│ └── index.html├── src│ ├── server.js│ └── services└── yarn.lock// src/services/shop.js// 店铺数据const memoryStorage = { '1001': { name: '良品铺子' }, '1002': { name: '来伊份' }, '1003': { name: '三只松鼠' }, '1004': { name: '百草味' },};// 模仿延时async function delay(ms = 200) { await new Promise((r) => setTimeout(r, ms));}class ShopService { async init() { await delay(); } async find({ id, pageIndex = 0, pageSize = 10 }) { await delay(); if (id) { return [memoryStorage[id]].filter(Boolean); } return Object.keys(memoryStorage) .slice(pageIndex * pageSize, (pageIndex + 1) * pageSize) .map((id) => ({ id, ...memoryStorage[id] })); } async modify({ id, values }) { await delay(); const target = memoryStorage[id]; if (!target) { return null; } return Object.assign(target, values); } async remove({ id }) { await delay(); const target = memoryStorage[id]; if (!target) { return false; } return delete memoryStorage[id]; }}// 单例模式let service;module.exports = async function () { if (!service) { service = new ShopService(); await service.init(); } return service;};以上服务层提供了店铺管理所需的根底业务逻辑，存储临时以内存和延时模仿，当初通过管制层向外裸露 RESTful 接口：
$ mkdir src/controllers # 新建 src/controllers 目录寄存管制层逻辑$ tree -L 2 -I node_modules # 展现除了 node_modules 之外的目录内容构造.├── Dockerfile├── package.json├── public│ └── index.html├── src│ ├── controllers│ ├── server.js│ └── services└── yarn.lock// src/controllers/shop.jsconst { Router } = require('express');const shopService = require('../services/shop');class ShopController { shopService; async init() { this.shopService = await shopService(); const router = Router(); router.get('/', this.getAll); router.get('/:shopId', this.getOne); router.put('/:shopId', this.put); router.delete('/:shopId', this.delete); return router; } getAll = async (req, res) => { const { pageIndex, pageSize } = req.query; const shopList = await this.shopService.find({ pageIndex, pageSize }); res.send({ success: true, data: shopList }); }; getOne = async (req, res) => { const { shopId } = req.params; const shopList = await this.shopService.find({ id: shopId }); if (shopList.length) { res.send({ success: true, data: shopList[0] }); } else { res.status(404).send({ success: false, data: null }); } }; put = async (req, res) => { const { shopId } = req.params; const { name } = req.query; const shopInfo = await this.shopService.modify({ id: shopId, values: { name }, }); if (shopInfo) { res.send({ success: true, data: shopInfo }); } else { res.status(404).send({ success: false, data: null }); } }; delete = async (req, res) => { const { shopId } = req.params; const success = await this.shopService.remove({ id: shopId }); if (!success) { res.status(404); } res.send({ success }); };}module.exports = async () => { const c = new ShopController(); return await c.init();};// src/controllers/index.jsconst { Router } = require('express');const shopController = require('./shop');module.exports = async function initControllers() { const router = Router(); router.use('/api/shop', await shopController()); return router;};// src/server.jsconst express = require('express');const { resolve } = require('path');const { promisify } = require('util');+const initControllers = require('./controllers');const server = express();const port = parseInt(process.env.PORT || '9000');const publicDir = resolve('public');async function bootstrap() { server.use(express.static(publicDir));+ server.use(await initControllers()); await promisify(server.listen.bind(server, port))(); console.log(`> Started on port ${port}`);}bootstrap();当初应用 yarn start 启动利用，通过浏览器即可间接拜访接口 http://localhost:9000/api/shop 与 http://localhost:9000/api/shop/1001。
补充一个店铺治理界面
以 JavaScript Modules 写一个店铺治理界面仅作演示（理论生产中倡议应用 React 或 Vue），调用 GET、PUT、DELETE 接口对店铺信息进行查问、批改、删除：
<!-- public/index.html --><html> <head> <meta charset="utf-8" /> </head> <body>- <h1>It works!</h1>+ <div id="root"></div>++ <script type="module">+ import { refreshShopList, bindShopInfoEvents } from './index.js';++ async function bootstrap() {+ await refreshShopList();+ await bindShopInfoEvents();+ }++ bootstrap();+ </script> </body></html>// public/index.jsexport async function refreshShopList() { const res = await fetch('/api/shop'); const { data: shopList } = await res.json(); const htmlItems = shopList.map( ({ id, name }) => `<li data-shop-id="${id}"> <div data-type="text">${name}</div> <input type="text" placeholder="输出新的店铺名称" /> <a href="#" data-type="modify">确认批改</a> <a href="#" data-type="remove">删除店铺</a></li>` ); document.querySelector('#root').innerHTML = `<h1>店铺列表：</h1><ul class="shop-list">${htmlItems.join('')}</ul>`;}export async function bindShopInfoEvents() { document.querySelector('#root').addEventListener('click', async (e) => { e.preventDefault(); switch (e.target.dataset.type) { case 'modify': await modifyShopInfo(e); break; case 'remove': await removeShopInfo(e); break; } });}export async function modifyShopInfo(e) { const shopId = e.target.parentElement.dataset.shopId; const name = e.target.parentElement.querySelector('input').value; await fetch(`/api/shop/${shopId}?name=${encodeURIComponent(name)}`, { method: 'PUT', }); await refreshShopList();}export async function removeShopInfo(e) { const shopId = e.target.parentElement.dataset.shopId; const res = await fetch(`/api/shop/${shopId}`, { method: 'DELETE' }); await refreshShopList();}拜访 http://localhost:9000/ 即可体验店铺治理性能：
本章源码
host1-tech/nodejs-server-examples - 01-api-and-layering
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