簡單工廠

簡單工廠模式(Simple Factory Pattern)：又稱為靜態工廠方法(Static Factory Method)模式，它屬於類建立型模式。在簡單工廠模式中，可以根據引數的不同返回不同類的例項。簡單工廠模式專門定義一個類來負責建立其他類的例項，被建立的例項通常都具有共同的父類。

例如:

自行車商店 ,客戶要求不同的型別(編號)的車,返回不同自行車的例項

   //定義一個介面類
    var Interface = function (name,methods) {
        if(arguments.length!=2){
            throw new Error('必須輸入兩個引數,當前個數'+arguments.length);
        };
        this.name = name; //介面名
        this.methods = []; //函式名
        for(var i=0;i<methods.length;i++){
            if(typeof methods[i] !== 'string'){
                throw new Error('方法名引數必須為string');
            }else{
                this.methods.push(methods[i]);
            }

        }
    };
    //定義靜態方法,檢驗實現介面和實現類 引數object為實現類物件

    Interface.ensureImplements = function (object) {
        if(arguments.length<2){
            throw new Error('必須輸入兩個引數,當前個數' + arguments.length);
            return;
        };
        for(var i =1;i<arguments.length;i++){
            var interface = arguments[i];
            if(interface.constructor != Interface){
                throw new Error("介面沒有實現");
            };
            for(var j=0;j<interface.methods.length;j++){
                var method = interface.methods[j];
                if(!object[method] || typeof object[method]!=='function'){
                    throw new Error("介面名:"+interface.name+"方法名："+method+"沒找到");
                }
            }
        }

    };
    //封裝的繼承的方法
    function extend(subClass,superClass) {
        var f = function () {};
        f.prototype =superClass.prototype;
        subClass.prototype = new f();
        subClass.prototype.constructor = subClass;
        subClass.superclass =superClass.prototype;
        if(superClass.prototype.constructor==Object.prototype.constructor){
            superClass.prototype.constructor =superClass;
        }
    }


   //自行車類 
    function Bicycle(name,price,type,style) {
        this.name = name || "一般車";
        this.price = price || 300;
        this.type = type || 1103;
        this.style = style;
        this.getInfo =function () {
            return "型號："+this.type + "名稱："+this.name+"售價："+ this.price;
        }
        this.styleChose = function () {
            return "樣式"+this.style+"種";
        }

    }
	//好車
    function GoodBicke(name,price,type,style) {
        GoodBicke.superclass.constructor.call(this);
        this.name = name || "超好車";
        this.price = price || 10000;
        this.type = type || 1102;
        this.speed = 50;
        this.style = style || 20;
        this.run = function () {
            return "最大速度"+this.speed;
        }
    }
    //一般車
    function NormalBicke(type,name,price,style) {
        NormalBicke.superclass.constructor.call(this);
        this.name = name || "平價車";
        this.price = price || 500;
        this.type = type;
        this.style = style || 100;
        this.speed = 20;
        this.run = function () {
            return "最大速度"+this.speed;
        }

    }
    //壞車
    function BadBicke(name,price,type,style) {
        BadBicke.superclass.constructor.call(this);
        this.name = name;
        this.price = price;
        this.type = type;
        this.style = style;
        this.speed = 10;
        this.run = function () {
            return "最大速度"+this.speed;
        }

    }
	//繼承自行車類
    extend(GoodBicke,Bicycle);
    extend(NormalBicke,Bicycle);
    extend(BadBicke,Bicycle);

    /*
    定義介面
    * */

    var Bicke = new Interface('Bicke',['run','styleChose','getInfo']);
    //自行車商店類
    function shop() {};
    shop.prototype={
    //賣自行車
        sellBicke:function (type) {
            var bicke = null;
            switch (type){
                case 1101:
                    bicke = new GoodBicke();
                    break;
                case 1102:
                    bicke = new BadBicke('差車',100,type);
                    break;
                default:
                    bicke = new NormalBicke(type);
            }

            Interface.ensureImplements(bicke,Bicke);

            return bicke;
        }
    }
  //測試::
  
    var person = new shop;
    var b = person.sellBicke(1101);
    console.log(b.getInfo());
    console.log(b.run());