http.createServer 详解 并 实现 use，get，post，all 等方法

const http = require('http');
const hostname = '127.0.0.1';
const port = 3000;
const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello, World!\n');
});
/** 
  注意，设置了 hostname 就只开放对应的hostname访问了哦
  Linux 可以使用 netstat -ntpl检查端口开放情况
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1380/sshd           
tcp        0      0 127.0.0.1:3000          0.0.0.0:*               LISTEN      1794/node           
tcp6       0      0 :::80                   :::*                    LISTEN      3019/node           
tcp6       0      0 :::22                   :::*                    LISTEN      1380/sshd           
*/
server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

const http = require('http');
function addCookie(res, { name, value, expireHours }){
  var cookieString=name+"="+escape(value);
  //判断是否设置过期时间
  if(expireHours > 0){
    var date = new Date();
    date.setTime(date.getTime+expireHours*3600*1000);
    cookieString = cookieString+"; expire="+date.toGMTString();
  }
  const cookies = res.getHeader('Set-Cookie');
  cookies.push(cookieString);
  res.setHeader('Set-Cookie', cookies);
}
function getQuery(req) {
    const search = {};
  (req.originalUrl.split('?').slice(1) || []).forEach(item => {
    const [key, value] = item.split('=');
    search[key] = value; 
  })
  console.log(search);
  return search;
}
const server = http.createServer((req, res) => {
  console.log(req instanceof http.IncomingMessage); // true
  res.setHeader('Content-Type', 'text/html');
  res.setHeader('Set-Cookie', ['type=ninja', 'language=javascript']);
  const contentType = res.getHeader('content-type');
  // 'text/html'
  console.log(contentType)
  addCookie(res, {name: "ljy998", value: "999", expireHours: 30})
  const cookies = res.getHeader('set-cookie');
  // ['type=ninja', 'language=javascript']
  console.log(cookies)
  // Object
  console.log(typeof cookies)
  // 每次用户请求都会进入此方法。
  // http://127.0.0.1:3000/index.html?abc=666
  // /index.html?abc=666 GET undefined undefined undefined
  res.end(`${req.url} ${req.method} ${req.query} ${req.params} ${req.body}`);
});
server.on('clientError', (err, socket) => {
  socket.end('HTTP/1.1 400 Bad Request\r\n\r\n');
});
server.listen(3000, function(){
  console.log("web service start, port 3000")
});

use 的实现demo

const http = require('http');
function call(handle, route, err, req, res, next) {
    var arity = handle.length;
    var error = err;
    var hasError = Boolean(err);
    try {
      if (hasError && arity === 4) {
        // error-handling middleware
        handle(err, req, res, next);
        return;
      } else if (!hasError && arity < 4) {
        // request-handling middleware
        handle(req, res, next);
        return;
      }
    } catch (e) {
      // replace the error
      error = e;
    }
    // continue
    next(error);
  }
const proto = {};
proto.handle = function handle(req, res) {
  var index = 0;
  var stack = this.stack;
  function next(err) {
    var layer = stack[index++];
    var route = layer.route;
    call(layer.handle, route, err, req, res, next);
  }
  next();
}
proto.use = function use(route, fn) { // 支持只传入一个fn
  var handle = fn;
  var path = route;
  // default route to '/'
  if (typeof route !== 'string') { // 支持只传入一个fn
    handle = route;
    path = '/';
  }
  if (path[path.length - 1] === '/') {
    path = path.slice(0, -1);
  }
  this.stack.push({ route: path, handle: handle });
}
function createServer() {
  function app(req, res, next){ 
    // 首次的时候没有next， next = undefined
    console.log(req.url)
    app.handle(req, res, next); 
  }
  app.use = proto.use;
  app.handle = proto.handle;
  app.route = '/';
  app.stack = [];
  return app;
}
const app = createServer()
app.use(function(req, res, next) {
  res.__fn = function () {
    console.log("__fn")
    return 'hello world'
  }
  next()
})
app.use(function(req, res, next) {
    const result = res.__fn()
    res.end(result)
})
// http.createServer(fn) 中的 fn 所有的http请求都会进入这个方法
const server = http.createServer(app)
server.listen(3000, function(){
  console.log("web service start, port 3000")
});