http.createServer(app).listen(app.get('port'), function(){

  console.log('Express server listening on port ' + app.get('port'));

});

/**

 * Module dependencies.

 */

var connect = require('connect')

  , proto = require('./application')

  , Route = require('./router/route')

  , Router = require('./router')

  , req = require('./request')

  , res = require('./response')

  , utils = connect.utils;

/**

 * Expose `createApplication()`.

 */

exports = module.exports = createApplication;

/**

 * Expose mime.

 */

exports.mime = connect.mime;

/**

 * Create an express application.

 *

 * @return {Function}

 * @api public

 */

function createApplication() {

  var app = connect();

  //将application中的方法全部拷贝到connect对象上去。

  utils.merge(app, proto);

  //设置app 的request对象的原型为req，本身的属性为connect对象

  app.request = { __proto__: req, app: app };

  //设置app的response对象原型为res ，本身的属性为connect对象

  app.response = { __proto__: res, app: app };

  //调用application中的方法init

  app.init();

  return app;

}

/**

 * Expose connect.middleware as express.*

 * for example `express.logger` etc.

 */

/**

 * 加载connect模块中得所有中间件

 */

for (var key in connect.middleware) {

  Object.defineProperty(

      exports

    , key

    , Object.getOwnPropertyDescriptor(connect.middleware, key));

}

/**

 * Error on createServer().

 */

/**

 *  将创建服务器的方法输出

 * @returns {Function}

 */

exports.createServer = function(){

  console.warn('Warning: express.createServer() is deprecated, express');

  console.warn('applications no longer inherit from http.Server,');

  console.warn('please use:');

  console.warn('');

  console.warn('  var express = require("express");');

  console.warn('  var app = express();');

  console.warn('');

  //加载创建应用程序的方法，开始创建application

  return createApplication();

};

/**

 * Expose the prototypes.

 */

exports.application = proto;

exports.request = req;

exports.response = res;

/**

 * Expose constructors.

 */

exports.Route = Route;

exports.Router = Router;

// Error handler title

exports.errorHandler.title = 'Express';

function createApplication() {

  var app = connect();

  //将application中的方法全部拷贝到connect对象上去。

  utils.merge(app, proto);

  //设置app 的request对象的原型为req，本身的属性为connect对象

  app.request = { __proto__: req, app: app };

  //设置app的response对象原型为res ，本身的属性为connect对象

  app.response = { __proto__: res, app: app };

  //调用application中的方法init

  app.init();

  return app;

}

app.init = function(){

  this.cache = {};

  this.settings = {};

  this.engines = {};

  //默认配置

  this.defaultConfiguration();

};

app.defaultConfiguration = function(){

  // default settings

  this.enable('x-powered-by');

  this.enable('etag');

  this.set('env', process.env.NODE_ENV || 'development');

  this.set('subdomain offset', 2);

  debug('booting in %s mode', this.get('env'));

  // implicit middleware

  //调用中间件

  this.use(connect.query());

  this.use(middleware.init(this));

  // inherit protos

  //继承原型

  this.on('mount', function(parent){

    this.request.__proto__ = parent.request;

    this.response.__proto__ = parent.response;

    this.engines.__proto__ = parent.engines;

    this.settings.__proto__ = parent.settings;

  });

  //router

  //路由

  this._router = new Router(this);

  this.routes = this._router.map;

  this.__defineGetter__('router', function(){

    this._usedRouter = true;

    this._router.caseSensitive = this.enabled('case sensitive routing');

    this._router.strict = this.enabled('strict routing');

    return this._router.middleware;

  });

  // setup locals

  this.locals = locals(this);

  // default locals

  this.locals.settings = this.settings;

  // default configuration

  this.set('view', View);

  this.set('views', process.cwd() + '/views');

  this.set('jsonp callback name', 'callback');

  this.configure('development', function(){

    this.set('json spaces', 2);

  });

  this.configure('production', function(){

    this.enable('view cache');

  });

};