Node.js 常见设计模式详解：单例、适配器、装饰与观察者

/*singleInstance.js*/
var _instance = null;//定义初始化_instance
module.exports = function(time){
   function Car(time){
     this.time = time;
   }
   this.getInstance = function(){
     if(_instance != null){
       return _instance;
     }else{
       return new Car(time);
     }
   }
}

/*target.js*/
module.exports = function(){
  this.request = function(){//原接口
    console.log('Target::request');
  }
}

/*adapter.js*/
var util = require('util');
var Target = require('./target.js');
var Adaptee = require('./adaptee.js');
function Adapter(){
  Target.call(this);
  this.request = function(){//重写原接口
    var adapteeObj = new Adaptee();//重写的内容
    adapteeObj.specialRequest();
  }
}
util.inherits(Adapter, Target);//通过继承原模块, 获得原接口
module.exports = Adapter;

/*Base.js*/
module.exports = function(){
  this.dosomething = function(){
   console.log("Nice to meet u.");
  }
}

/*Decorator.js*/
var util = require("util);
var Base = require('./Base');
function Decorator(){
  Base.call(this);
  this.dosomething = function(){
     Base.dosomething();
     console.log('I am a decorator');//拓展内容
  }
}
util.inherits(Decorator, Base);//继承
module.exports = Decorator;

/*被观察者*/
module.exports = function(){
  var m_obserSet = [];//观察者列表
  var _self = this;
  this.addObser = function(observer){
    m_obserSet.push(observer);//添加观察者
  }
  this.doAction = function(){
    console.log("Observable do some action");
    _self.notifyAllObeser();
  }
  this.notifyAllObeser = function(){//发生动作
    for(var key in m_obserSet){//逐个通知观察者
      m_obserSet[key].update();//观察者执行回调
    }
  }
}