前端微前端架构实战：如何避免应用变成巨石

把所有组件都塞进一个大文件里，无论有用没用，全堆在一起。这种结构一旦膨胀，谁碰谁崩。

解决方案

1. Module Federation (Webpack 5)

这是目前最推荐的方案之一，利用 Webpack 5 的原生能力实现运行时模块共享。

主机应用配置

// webpack.config.js
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  plugins: [
    new ModuleFederationPlugin({
      name: 'host',
      remotes: {
        dashboard: 'dashboard@http://localhost:3001/remoteEntry.js',
        users: 'users@http://localhost:3002/remoteEntry.js',
        products: 'products@http://localhost:3003/remoteEntry.js',
        orders: 'orders@http://localhost:3004/remoteEntry.js',
        settings: 'settings@http://localhost:3005/remoteEntry.js',
      },
      shared: {
        react: { singleton: true, requiredVersion: '^18.2.0' },
        'react-dom': { singleton: true, requiredVersion: '^18.2.0' },
      },
    }),
  ],
};

这里的关键是 shared 字段，确保 React 等核心库只加载一份，避免重复消耗内存。远程应用只需暴露对应的组件即可。

远程应用配置

// dashboard/webpack.config.js
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  plugins: [
    new ModuleFederationPlugin({
      name: 'dashboard',
      filename: 'remoteEntry.js',
      exposes: {
        './Dashboard': './src/Dashboard',
      },
      shared: {
        react: { singleton: true, requiredVersion: '^18.2.0' },
        'react-dom': { singleton: true, requiredVersion: '^18.2.0' },
      },
    }),
  ],
};

主机应用使用

// App.jsx
import React, { lazy, Suspense } from 'react';
import Header from './components/Header';
import Sidebar from './components/Sidebar';

const Dashboard = lazy(() => import('dashboard/Dashboard'));
const Users = lazy(() => import('users/Users'));
const Products = lazy(() => import('products/Products'));
const Orders = lazy(() => import('orders/Orders'));
const Settings = lazy(() => import('settings/Settings'));

function App() {
  return (
    <div>
      <Header />
      <div>
        <Sidebar />
        <main>
          <Suspense fallback={<div>加载中...</div>}>
            <Dashboard />
            <Users />
            <Products />
            <Orders />
            <Settings />
          </Suspense>
        </main>
      </div>
    </div>
  );
}

export default App;

通过 lazy 和 Suspense，我们可以按需加载这些远程模块，显著减少首屏体积。

2. Single-SPA

如果你不想被 Webpack 绑定，Single-SPA 提供了更底层的框架无关支持。

注册应用

// src/registerApplications.js
import { registerApplication, start } from 'single-spa';

registerApplication({
  name: '@my-org/dashboard',
  app: () => import('@my-org/dashboard'),
  activeWhen: (location) => location.pathname.startsWith('/dashboard'),
});

registerApplication({
  name: '@my-org/users',
  app: () => import('@my-org/users'),
  activeWhen: (location) => location.pathname.startsWith('/users'),
});

start();

这里通过 URL 路径来激活不同的微应用，非常适合多路由场景。

微应用生命周期

// packages/dashboard/src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import singleSpaReact from 'single-spa-react';
import Dashboard from './Dashboard';

const lifecycles = singleSpaReact({
  React,
  ReactDOM,
  rootComponent: Dashboard,
  errorBoundary(err, info, props) {
    return <div>应用出错了</div>;
  },
});

export const bootstrap = lifecycles.bootstrap;
export const mount = lifecycles.mount;
export const unmount = lifecycles.unmount;

3. Qiankun

基于 Single-SPA 封装，更适合企业级开发，提供了沙箱隔离等开箱即用的功能。

主应用注册

// src/main.js
import { registerMicroApps, start } from 'qiankun';

registerMicroApps([
  {
    name: 'dashboard',
    entry: '//localhost:3001',
    container: '#micro-app-container',
    activeRule: '/dashboard',
  },
  {
    name: 'users',
    entry: '//localhost:3002',
    container: '#micro-app-container',
    activeRule: '/users',
  },
]);

start();

微应用适配

// packages/dashboard/src/main.js
import { createApp } from 'vue';
import App from './App.vue';
import router from './router';

let instance = null;

function render(props) {
  const { container } = props;
  instance = createApp(App);
  instance.use(router);
  instance.mount(container ? container.querySelector('#app') : '#app');
}

if (!window.__POWERED_BY_QIANKUN__) {
  render({});
}

export async function bootstrap() {
  console.log('dashboard bootstraped');
}

export async function mount(props) {
  console.log('dashboard mounted', props);
  render(props);
}

export async function unmount() {
  console.log('dashboard unmounted');
  instance.unmount();
  instance = null;
}

注意 __POWERED_BY_QIANKUN__ 全局变量的判断，这是防止样式冲突和重复渲染的关键。

核心建议

微前端不是银弹，但在特定规模下是必要的选择。将应用拆分成多个独立的微应用，团队协作更高效，构建时间更短，再也不用担心巨石应用的问题了。根据团队技术栈和业务复杂度，选择合适的方案落地即可。