二、koa+React服务端渲染:添加路由

目标

上一次做了一个简单的hello world,这个我给单页面应用加入路由,这里我用的是react-router v4。这里为了简单就只设置两个页面,一个home页面,一个about页面

项目设置

安装路由包

npm install react-router react-router-dom --save

编写应用

  1. 创建home和about组件
    /app/web/component/home/home.js
import React from 'react';

const Home = () => {
  return (
    
Home
); }; export default Home;

/app/web/component/about/about.js

import React from 'react';

const About = () => {
  return (
    
About
); }; export default About;
  1. 设置浏览器端路由
    /app/web/component/app/admin.js
import React from 'react';
import { Route, Link } from 'react-router-dom';
import Home from '../home/home';
import About from '../about/about';

const App = ({ msg }) => {
  return (
    
Hello { msg }
  • Home
  • About

) }; export default App;

这样当访问/admin的时候就会渲染home组件,访问/admin/about就会渲染about组件
然后我们期望浏览器端是使用H5的history API实现路由,所以我们使用BrowserRouter,修改
/app/web/page/browser/admin.js

import React from 'react';
import ReactDOM from 'react-dom';
import { BrowserRouter } from 'react-router-dom';

import AdminApp from '../../component/app/admin';

ReactDOM.hydrate((
  
    
  
), document.getElementById('root'));
  1. 设置服务端路由
    首先,我们要确保当浏览器访问/admin 和 /admin/about这样的以/admin开头的路由的时候,服务器能够渲染出页面。也就是说,当访问/admin/about的时候,服务器不能返回404。我们修改
    /app/router.js
const admin = require('./controller/admin');

module.exports = app => {
  const { router } = app;
  // 匹配所有/admin开头的url
  router.get('/admin(.*)', admin.admin);
};

/admin(.*) 代表所有访问以/admin开头的url时,都会被admin这个controller处理。这样就不会返回404了。
当然,光是不反回404还是不够的,我们需要react根据url渲染出对应的html文本,我们还需要修改
/app/web/page/server/admin.js

import React from 'react';
import { StaticRouter } from 'react-router-dom';

import AdminLayout from '../../component/layout/admin_layout';
import AdminApp from '../../component/app/admin';

const server = context => {
  return (
    
      
        
      
    
  )
};
export default server;

上面代码关键点在于给StaticRouter传入了一个context.url,但是目前为止,我们还没有再服务端传入这个属性,所有需要修改
/app/middleware/react_view.js

const assert = require('assert');
const path = require('path');
const fs = require('fs');
const ReactDOMServer = require('react-dom/server');

const defaults = {
  view: path.resolve(process.cwd(), 'view'),
  extname: 'js'
};

module.exports = (options, app) => {
  options = options || {};
  options = Object.assign({}, defaults, options);
  assert(typeof options.view === 'string', 'options.view required, and must be a string');
  assert(fs.existsSync(options.view), `Directory ${options.view} not exists`);
  options.extname = options.extname.trim().replace(/^\.?/, '.');
  app.context.render = function (filename, _context) {
    if (!path.extname(filename)) {
      filename += options.extname;
    }
    let filepath = path.isAbsolute(filename) ? filename : path.resolve(options.view, filename);
    const context = Object.assign({}, this.state, _context);
    // 添加 url 属性
    if (!context.url) {
      context.url = this.url;
    }
    try {
      let view = require(filepath);
      view = view.default || component;
      this.body = ReactDOMServer.renderToString(view(context));
      this.type = 'html';
    } catch (err) {
      err.code = 'REACT';
      throw err;
    }
  }
};

目前为止,路由就加上了,执行命令

npm run build && npm run start

在浏览器输入http://localhost:3000/admin应该能看到

输入http://localhost:3000/admin/about应该能看到

项目地址:https://github.com/leitc/isomorphic-react/tree/0.2

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