koa2路由

例子

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

app.use( async ( ctx ) => {
  let url = ctx.request.url
  ctx.body = url
})
app.listen(9999)

现在你访问 (http://localhost:3000/hello/world)页面会输出hello/world,现在也就是说请求中url就是当前的访问的路径名称，可以根据ctx.request.url通过一定的判断或者正在就可以定制出所需要的路由

1559122941(1).jpg

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(9999)
console.log("[demo] start-quick is starting at port 9999")

执行node -harmony index.js
就可以看到输出页面

image.png

index.html

image.png