Node.js 路由的实现方法

          url.parse(string).query
                      |
      url.parse(string).pathname   |
            |          |
            |          |
           ------ -------------------
http://localhost:8888/start?foo=bar&hello=world
                ---    -----
                 |     |
                 |     |
       querystring.parse(queryString)["foo"]  |
                      |
             querystring.parse(queryString)["hello"]

// 代码route（）方法为第二个创建的router.js那的方法。我们在这里使用
const http = require('http')
const url = require('url')

function start(route){
  function onRequest(request, response) {
    let pathName = url.parse(request.url).pathname // 通过url获取到当前访问路径
    console.log('Request for ' + pathName + 'received.')
    route(pathName,response)
  }
  http.createServer(onRequest).listen(8888)
  console.log('Server has started')
}
exports.start = start

// 通过传递过来到pathname，来进行不同的操作，如果是根目录，打印hello world
// 如果是/index 打印 pathname :/index
// 如果是其他 打印404
function route(pathname,response) {
  console.log('About to route a request for ' + pathname)
  response.writeHead(200, {'Content-Type' : 'text/plain'})
  if(pathname == '/') {
    response.write('Hello World')
    response.end()
  }else if(pathname == '/index'){
    response.write('pathname :/index')
    response.end()
  } else {
    response.write('404')
    response.end()
  }
  
}
exports.route = route

const server = require('./server')
const router = require('./router')

server.start(router.route)