application.js

1 模块依赖

var finalhandler = require('finalhandler');
var Router = require('./router');
var methods = require('methods');
var middleware = require('./middleware/init');
var query = require('./middleware/query');
var debug = require('debug')('express:application');
var View = require('./view');
var http = require('http');
var compileETag = require('./utils').compileETag;
var compileQueryParser = require('./utils').compileQueryParser;
var compileTrust = require('./utils').compileTrust;
var deprecate = require('depd')('express');
var flatten = require('array-flatten');
var merge = require('utils-merge');
var resolve = require('path').resolve;
var setPrototypeOf = require('setprototypeof')
var slice = Array.prototype.slice;

2 导出对象

var app = exports = module.exports = {};

整个文件暴露就是这个app对象初始化时里面没有东西的后面会补充。

3 app.init()

app.init = function init() {
  this.cache = {};
  this.engines = {};
  this.settings = {};

  this.defaultConfiguration();
};

添加三个空对象属性 cache engines setting 后面会补充内容

4 app.defaultConfiguration()

app.defaultConfiguration = function defaultConfiguration() {
  var env = process.env.NODE_ENV || 'development';

  // default settings
  this.enable('x-powered-by');
  this.set('etag', 'weak');
  this.set('env', env);
  this.set('query parser', 'extended');
  this.set('subdomain offset', 2);
  this.set('trust proxy', false);

  // trust proxy inherit back-compat
  Object.defineProperty(this.settings, trustProxyDefaultSymbol, {
    configurable: true,
    value: true
  });

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

  this.on('mount', function onmount(parent) {
    // inherit trust proxy
    if (this.settings[trustProxyDefaultSymbol] === true
      && typeof parent.settings['trust proxy fn'] === 'function') {
      delete this.settings['trust proxy'];
      delete this.settings['trust proxy fn'];
    }

    // inherit protos
    setPrototypeOf(this.request, parent.request)
    setPrototypeOf(this.response, parent.response)
    setPrototypeOf(this.engines, parent.engines)
    setPrototypeOf(this.settings, parent.settings)
  });

  // setup locals
  this.locals = Object.create(null);

  // top-most app is mounted at /
  this.mountpath = '/';

  // default locals
  this.locals.settings = this.settings;

  // default configuration
  this.set('view', View);
  this.set('views', resolve('views'));
  this.set('jsonp callback name', 'callback');

  if (env === 'production') {
    this.enable('view cache');
  }

  Object.defineProperty(this, 'router', {
    get: function() {
      throw new Error('\'app.router\' is deprecated!\nPlease see the 3.x to 4.x migration guide for details on how to update your app.');
    }
  });
};

1.获取环境

 var env = process.env.NODE_ENV || 'development';

2.设置网络有关的配置

[tag]
[x-powered-by]
[query parser]
[subdomain offset]
[trust proxy]

我所了解的只有x-powered-by 是隐藏响应头的重要信息 query parser 是查询字符串解析 trust proxy 使用代理服务器 subdomain offset 所忽略的字符偏移量(不过不知道有什么用。。。) 以后了解后会补上

3.在setting设置为trustProxyDefaultSymbol的属性
4.设置mount事件当使用代理服务器或者子应用时候才会响应事件(主要用于子域名时使用)
5.设置local属性
6.设置项目根目录
7.将app的setting属性给local属性中的setting
8.用app.set()方法在app.setting属性上做设置
9.如果环境是production 就开启view cache(页面缓存的作用)
10.设置无法直接在app.router上获取路由

初始化app的属性就是这两个函数进行的

5 app.lazyrouter�()

app.lazyrouter = function lazyrouter() {
  if (!this._router) {
    this._router = new Router({
      caseSensitive: this.enabled('case sensitive routing'),
      strict: this.enabled('strict routing')
    });

    this._router.use(query(this.get('query parser fn')));
    this._router.use(middleware.init(this));
  }
};

对app._router的属性懒加载

源码解释为啥这段代码不放在初始化的方法上因为担心app.setting属性会有改变所以等他初始化后再创建

6 app.handle()

app.handle = function handle(req, res, callback) {
  var router = this._router;

  // final handler
  var done = callback || finalhandler(req, res, {
    env: this.get('env'),
    onerror: logerror.bind(this)
  });

  // no routes
  if (!router) {
    debug('no routes defined on app');
    done();
    return;
  }

  router.handle(req, res, done);
};

1.获取路由属性_router
2.判断是否有callback 假如没有就finalhandler (这finalhandler是一个只进行错误处理的callback)
3.判断是否没有router (不过这是express开发者的调试判断正常是不会进去的)
4.然后交由路由处理

7 app.use()

app.use = function use(fn) {
  var offset = 0;
  var path = '/';

  // default path to '/'
  // disambiguate app.use([fn])
  if (typeof fn !== 'function') {
    var arg = fn;

    while (Array.isArray(arg) && arg.length !== 0) {
      arg = arg[0];
    }

    // first arg is the path
    if (typeof arg !== 'function') {
      offset = 1;
      path = fn;
    }
  }

  var fns = flatten(slice.call(arguments, offset));

  if (fns.length === 0) {
    throw new TypeError('app.use() requires middleware functions');
  }

  // setup router
  this.lazyrouter();
  var router = this._router;

  fns.forEach(function (fn) {
    // non-express app
    if (!fn || !fn.handle || !fn.set) {
      return router.use(path, fn);
    }

    debug('.use app under %s', path);
    fn.mountpath = path;
    fn.parent = this;

    // restore .app property on req and res
    router.use(path, function mounted_app(req, res, next) {
      var orig = req.app;
      fn.handle(req, res, function (err) {
        setPrototypeOf(req, orig.request)
        setPrototypeOf(res, orig.response)
        next(err);
      });
    });

    // mounted an app
    fn.emit('mount', this);
  }, this);

  return this;
};

1.设置路径变量path 和偏移变量offset
2.进行判断：

[如果参数不是函数] 1.把参数的值传给变量 2.假如该变量是复合数组则一直循环直到第一个值不是数组 3.如果该变量还不是函数则偏移变量为1 路径变量为该变量的值

3.通过偏移变量获取下一个参数，并将其扁平化(即将复合数组变成为一个数组) 4.假如下一个参数都没有callback 则报错 5.懒加载获取路由 6.对callback数组进行循环处理

[假如该callback不含handle和set时] 则使用router.use方法
[假如有] 1.设置子应用的mountpath为路径变量 2.设置子应用的父应用 3.重新保存子应用的req属性和res属性 4.触发emit事件

8 app.route()

app.route = function(path){
  this.lazyrouter();
  return this._router.route(path);
};

Router.route的代理方法

9 app.engine()

app.engine = function engine(ext, fn) {
  if (typeof fn !== 'function') {
    throw new Error('callback function required');
  }

  // get file extension
  var extension = ext[0] !== '.'
    ? '.' + ext
    : ext;

  // store engine
  this.engines[extension] = fn;

  return this;
};

假如所设置的引擎没加后缀符号. 则补充上并将其设置在engines属性上

10 app.param()

app.param = function param(name, fn) {
  this.lazyrouter();

  if (Array.isArray(name)) {
    for (var i = 0; i < name.length; i++) {
      this.param(name[i], fn);
    }

    return this;
  }

  this._router.param(name, fn);

  return this;
};

Router.param()的代理方法假如name是数组则遍历调用Router.param()

11 app.set()

app.set = function set(setting, val) {
  if (arguments.length === 1) {
    // app.get(setting)
    return this.settings[setting];
  }

  debug('set "%s" to %o', setting, val);

  // set value
  this.settings[setting] = val;

  // trigger matched settings
  switch (setting) {
    case 'etag':
      this.set('etag fn', compileETag(val));
      break;
    case 'query parser':
      this.set('query parser fn', compileQueryParser(val));
      break;
    case 'trust proxy':
      this.set('trust proxy fn', compileTrust(val));

      // trust proxy inherit back-compat
      Object.defineProperty(this.settings, trustProxyDefaultSymbol, {
        configurable: true,
        value: false
      });

      break;
  }

  return this;
};

将想要保存的配置信息保存在app的setting属性
1.假如只有一个参数则是getter方法
2.在setting属性设置键值
3.假如要设置的键名是etag query parser trust proxy其中一个则另做处理

12 app.path()

app.path = function path() {
  return this.parent
    ? this.parent.path() + this.mountpath
    : '';
};

返回app的绝对路径假如是子应用则在父应用的绝对路径加子应用的绝对路径

13 app.enabled()

app.enabled = function enabled(setting) {
  return Boolean(this.set(setting));
};

检查该setting是不是可用(enable)

14 app.disabled()

app.disabled = function disabled(setting) {
  return !this.set(setting);
};

检查该setting是不是不可用(disable)

15 app.enable()

app.enable = function enable(setting) {
  return this.set(setting, true);
};

设置该setting为可用

16 app.disable()

app.disable = function disable(setting) {
  return this.set(setting, false);
};

设置该setting为不可用

17 methods.foreach()

methods.forEach(function(method){
  app[method] = function(path){
    if (method === 'get' && arguments.length === 1) {
      // app.get(setting)
      return this.set(path);
    }

    this.lazyrouter();

    var route = this._router.route(path);
    route[method].apply(route, slice.call(arguments, 1));
    return this;
  };
});

methods是模块methods所暴露的方法
是为了获取http所有VERB
1.将VERB数组进行遍历
2.给app添加所有VERB的方法
3.该方法是假如get方法而且参数只有一个则判断为是调用app.set方法
4.假如不是则调用route.VERB方法进行处理

18 app.all()

app.all = function all(path) {
  this.lazyrouter();

  var route = this._router.route(path);
  var args = slice.call(arguments, 1);

  for (var i = 0; i < methods.length; i++) {
    route[methods[i]].apply(route, args);
  }

  return this;
};

调用app中的每一个VERB方法

19 app.listen()

app.listen = function listen() {
  var server = http.createServer(this);
  return server.listen.apply(server, arguments);
};

可以跟前面的express.js中的代码:

var app = function(req, res, next) {
    app.handle(req, res, next);
  };

进行呼应为什么app一开始是一个函数因为会放在http.createServer(req,res,next)的回调函数中因此整个express可以说是一个函数也是在这里做文章后面的调用也是交给了app.handle()处理

20 app.render()

app.render = function render(name, options, callback) {
  var cache = this.cache;
  var done = callback;
  var engines = this.engines;
  var opts = options;
  var renderOptions = {};
  var view;

  // support callback function as second arg
  if (typeof options === 'function') {
    done = options;
    opts = {};
  }

  // merge app.locals
  merge(renderOptions, this.locals);

  // merge options._locals
  if (opts._locals) {
    merge(renderOptions, opts._locals);
  }

  // merge options
  merge(renderOptions, opts);

  // set .cache unless explicitly provided
  if (renderOptions.cache == null) {
    renderOptions.cache = this.enabled('view cache');
  }

  // primed cache
  if (renderOptions.cache) {
    view = cache[name];
  }

  // view
  if (!view) {
    var View = this.get('view');

    view = new View(name, {
      defaultEngine: this.get('view engine'),
      root: this.get('views'),
      engines: engines
    });

    if (!view.path) {
      var dirs = Array.isArray(view.root) && view.root.length > 1
        ? 'directories "' + view.root.slice(0, -1).join('", "') + '" or "' + view.root[view.root.length - 1] + '"'
        : 'directory "' + view.root + '"'
      var err = new Error('Failed to lookup view "' + name + '" in views ' + dirs);
      err.view = view;
      return done(err);
    }

    // prime the cache
    if (renderOptions.cache) {
      cache[name] = view;
    }
  }

  // render
  tryRender(view, renderOptions, done);
};

这个东西不是今晚要聊的板子所以以后要研究的时候再看接下来再研究router.js

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application.js

1 模块依赖

2 导出对象

3 app.init()

4 app.defaultConfiguration()

5 app.lazyrouter�()

6 app.handle()

7 app.use()

8 app.route()

9 app.engine()

10 app.param()

11 app.set()

12 app.path()

13 app.enabled()

14 app.disabled()

15 app.enable()

16 app.disable()

17 methods.foreach()

18 app.all()

19 app.listen()

20 app.render()

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application.md

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application.js

1 模块依赖

2 导出对象

3 app.init()

4 app.defaultConfiguration()

5 app.lazyrouter�()

6 app.handle()

7 app.use()

8 app.route()

9 app.engine()

10 app.param()

11 app.set()

12 app.path()

13 app.enabled()

14 app.disabled()

15 app.enable()

16 app.disable()

17 methods.foreach()

18 app.all()

19 app.listen()

20 app.render()