路由

koa2 原生路由实现

简单例子

const Koa = require('koa');
const app = new Koa();

app.use(async ctx => {
  let url = ctx.request.url;
  ctx.body = url;
});
app.listen(3000);

定制化的路由

源码文件目录

├── index.js
├── package.json
└── view
    ├── 404.html
    ├── index.html
    └── todo.html

demo 源码

const Koa = require('koa');
const fs = require('fs');
const app = new Koa();

/**
 * 用Promise封装异步读取文件方法
 * @param  {string} page html文件名称
 * @return {promise}
 */
function render(page) {
  return new Promise((resolve, reject) => {
    let viewUrl = `./view/${page}`;
    fs.readFile(viewUrl, 'binary', (err, data) => {
      if (err) {
        reject(err);
      } else {
        resolve(data);
      }
    });
  });
}

/**
 * 根据URL获取HTML内容
 * @param  {string} url koa2上下文的url，ctx.url
 * @return {string}     获取HTML文件内容
 */
async function route(url) {
  let view = '404.html';
  switch (url) {
    case '/':
      view = 'index.html';
      break;
    case '/index':
      view = 'index.html';
      break;
    case '/todo':
      view = 'todo.html';
      break;
    case '/404':
      view = '404.html';
      break;
    default:
      break;
  }
  let html = await render(view);
  return html;
}

app.use(async ctx => {
  let url = ctx.request.url;
  let html = await route(url);
  ctx.body = html;
});

app.listen(3000);
console.log('[demo] route-simple is starting at port 3000');

koa-router 中间件

# koa2 对应的版本是 7.x
npm install --save koa-router@7

const Koa = require('koa');
const app = new Koa();

const Router = require('koa-router');

let home = new Router();

// 子路由1
home.get('/', async ctx => {
  let html = `
    <ul>
      <li><a href="/page/helloworld">/page/helloworld</a></li>
      <li><a href="/page/404">/page/404</a></li>
    </ul>
  `;
  ctx.body = html;
});

// 子路由2
let page = new Router();
page
  .get('/404', async ctx => {
    ctx.body = '404 page!';
  })
  .get('/helloworld', async ctx => {
    ctx.body = 'helloworld page!';
  });

// 装载所有子路由
let router = new Router();
router.use('/', home.routes(), home.allowedMethods());
router.use('/page', page.routes(), page.allowedMethods());

// 加载路由中间件
app.use(router.routes()).use(router.allowedMethods());

app.listen(3000, () => {
  console.log('[demo] route-use-middleware is starting at port 3000');
});