express路由探析（续）

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 setup
app.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Router
app.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 handler
app.use(function(req, res, next) {
    var err = new Error(‘Not Found‘);
    err.status = 404;
    next(err);
});

// error handlers

// development error handler
// will print stacktrace
if (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 user
app.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;