var express = require(‘express‘);var path = require(‘path‘);var favicon = require(‘serve-favicon‘);var logger = require(‘morgan‘);var cookieParser = require(‘cookie-parser‘);var bodyParser = require(‘body-parser‘);var routes = require(‘./routes/index‘);var users = require(‘./routes/users‘);var fs = require(‘fs‘);var app = express();  // view engine setupapp.set(‘views‘, path.join(__dirname, ‘views‘));app.set(‘view engine‘, ‘ejs‘);// uncomment after placing your favicon in /public//app.use(favicon(__dirname + ‘/public/favicon.ico‘));app.use(logger(‘dev‘));  //从这里这里开始添加中间件，因为之前没添加过，所以会实例化一个Router，在实例化的时候会添加两个中间件（query和init），因此这个中间件是第三个app.use(bodyParser.json());app.use(bodyParser.urlencoded({ extended: false }));app.use(cookieParser());app.use(express.static(path.join(__dirname, ‘public‘)));app.use(‘/‘, routes); //routes是“./routes/index.js”文件中创建的Router实例，也就是通过这句代码在顶层Router里面添加了新的Routerapp.use(‘/users‘, users);//var count = routes.stack.length;var count = app._router.stack.count;var content = "";console.log(count);/*for (var i = 0; i<count; i++) {    content+=dump_obj(routes.stack[i]) + "\r\n\r\n";    console.log(app._router.stack[i]);};*/console.log(app._router.stack[7]);  //输出顶层Router中的一个特殊中间件，即app.use(‘/‘,routes)语句添加的routes，该中间件也是Router对象/*fs.writeFile(‘message.txt‘, content, function (err) {  if (err) throw err;  console.log(‘It\‘s saved!‘);});function dump_obj(myObject) {    var s = "";    for (var property in myObject) {     s = s + "\n "+property +": " + myObject[property] ;    }    return s;}*/
// catch 404 and forward to error handlerapp.use(function(req, res, next) {    var err = new Error(‘Not Found‘);    err.status = 404;    next(err);});// error handlers// development error handler// will print stacktraceif (app.get(‘env‘) === ‘development‘) {    app.use(function(err, req, res, next) {        res.status(err.status || 500);        res.render(‘error‘, {            message: err.message,            error: err        });    });}// production error handler// no stacktraces leaked to userapp.use(function(err, req, res, next) {    res.status(err.status || 500);    res.render(‘error‘, {        message: err.message,        error: {}    });});module.exports = app;

var express = require(‘express‘);var router = express.Router();  //这里新实例化一个Router，直接调用app(application.js)中的app.use()或app[method]能保证在app中的Router实例只有一个，但是我们仍然可以再手动实例化新的Router，app.Router其实是最顶层的中间件容器，只能有一个var users = {    ‘byvoid‘:{        name : "Carbo",        website : ‘http://www.byvoid.com‘    }};/*--------- test start 下面是测试代码，在新创建的Router中添加中间件，待会儿要输出进行验证 ---------*/var route = router.route(‘/user‘);route.get(function(req,res,next){},function(req,res){});  //第一个中间件添加了两个处理函数，下面的输出会进行验证router.all(‘user/:username‘,function(req,res,next){    if(users[req.params.username]){        next();    }    else{        next(new Error(req.params.username+‘does not exist.‘));    }});router.get(‘/user/:username‘,function(req,res){    res.send(JSON.stringify(users[req.params.username]));});

router.get(‘/user/:username‘,function(req,res){    res.send(‘user:‘ + req.params.username);});
/*--------- test end -----------*/

/* GET home page. */router.get(‘/‘, function(req, res) {  res.render(‘index‘, { title: ‘Express‘ });});module.exports = router;