大概实现思路：封装一个app对象，创建由（http创建）server属性，然后创建一个stack的数组，用来储存use上挂载的方法。 来了来请求，判断路径且循环调用stack里的方法。
app：代码如下
var http = require('http');
var url = require('url');
var proto = {
stack: []
};
function createServer() {
var app = {
task: function(req, res) {
app.handle(req, res);
}
}
//把proto中的属性拷贝到app对象里
Object.assign(app, proto);
return app;
}
//装载函数
proto.use = function(route, fn) {
var path = route;
var handle = fn;
if (typeof route != 'string') {
handle = route;
path = "/";
}
this.stack.push({
handle: handle,
path: path
});
}
//循环调用函数
proto.handle = function(req, res) {
var stack = this.stack;
var index = 0;
function next(err) {
var layer = stack[index++];
var route = layer.path;
var handle = layer.handle;
var path = url.parse(req.url).pathname;
//是否匹配路径,是否匹配开头
if (path.startsWith(route)) {
if (err) {
if (handle.length == 4) {
handle(err, req, res, next);
} else {
next(err);
}
} else {
handle(req, res, next);
}
} else {
next();
}
}
next();
}
proto.listen = function(port) {
var server = http.createServer(this.task);
server.listen(port);
}
module.exports = createServer;
git地址：https://github.com/hi363138911/express
个人博客： http://www.liangtongzhuo.com
