express源码（3）

//express.jsvar Application = require("./application");function createApplication(){    var app = new Application();    return app;}exports = module.exports = createApplication;//index.js
/*    这里是我们的业务模块*/var express = require("./app");var app = new express();app.use("/",function(req,res){    res.writeHead(200,{"Content-type":"text/plain"});//mime.json文件    res.end("Hello my homepage~!");});app.use("/dnedu",function(req,res){    res.writeHead(200,{"Content-type":"text/plain"});//mime.json文件    res.end("Hello,welcome to dnedu~!");});app.listen(3000);//app.js
//var express = require("./lib/express");exports = module.exports = require("./lib/express");//可以不用变量保存直接等于require引入的对象