[Decode error - output not utf-8]----------------------------- 购物清单 方便面 : 100 x 50 = 5000 | 4000 菊花茶 : 10 x 50 = 500 | 500----------------------------- 优惠使用 : 国庆1折优惠 购物合计 4500 -> 450[Finished in 0.6s]
首先封装收银机类，怎么把商品设进，怎么把收银金额输出。
然后封装商品，和金额独立
然后进行收银策略编写。打折，满返针对的是最后的结果。
收银机添加设置策略接口，调用原生金额接口，调用策略接口，获得策略后金额接口
下个需求到商品的具体折扣，譬如买几送几
封装策略到商品处，商品创建的时候根据自己的名字到工厂去领取自己的“福利”
后续还想实施，组合折扣，譬如买牙膏同时买牙刷，减5块钱
架构要大改了(・-・*) ，暂时搁置
/** * by JackChen 2016-3-15 19.20.01 * 看完马士兵老师策略模式后作业 * * 原文是讲解comparable接口 和 compareTo * * 所有实现了comparable接口的类都可以用于比较。 * * 而更高级的是，我不同场景需要不同的比较时，通过定制本类的比较器， * 借用比较器的compareTo，得到不同的比较结果 * * 已实现 * 1. 单个物品多个数量 * 2. 多个物品多个数量 * 3. 多个物品结算打印 * 4. 多个物品总金额折扣策略（几折、满返） * 5. 单个物品优惠策略（多少个送多少个） * * 待实现 * 6. 单个物品 买多个送多个 跟购物物品无关 * 7. 组合购买 *//// 收银策略类//普通收钱var NormalStrategy = function() { var self = this; self.type = "total"; self.description = "没有使用优惠";};NormalStrategy.prototype = {};NormalStrategy.prototype.constructor = NormalStrategy;NormalStrategy.prototype.desc = function() { return this.description;};NormalStrategy.prototype.discount = function(money) { return money;};//折扣策略var PrecentOffStrategy = function(description, precent) { var self = this; self.type = "total"; self.precent = precent; self.description = description + (precent*10) + "折优惠";};PrecentOffStrategy.prototype = new NormalStrategy();PrecentOffStrategy.prototype.constructor = PrecentOffStrategy;PrecentOffStrategy.prototype.desc = function() { return this.description;};PrecentOffStrategy.prototype.discount = function(money) { return money * this.precent;};//满返策略var GivebackStrategy = function(description, enough, giveback) { var self = this; self.type = "total"; self.enough = enough; self.giveback = giveback; self.description = description + "满"+ enough + "返" + giveback + "优惠";};GivebackStrategy.prototype = new NormalStrategy();GivebackStrategy.prototype.constructor = GivebackStrategy;GivebackStrategy.prototype.desc = function() { return this.description;};GivebackStrategy.prototype.discount = function(money) { if (money >= this.enough) { money -= this.giveback; }; return money;};/// 销售品种折扣工厂var SaleItemStrategyFactory = function() {};SaleItemStrategyFactory.prototype = {};SaleItemStrategyFactory.prototype.constructor = SaleItemStrategyFactory;SaleItemStrategyFactory.prototype.getInstance = function(name) { var self = this; var strategy = null; switch (name) { case "方便面": strategy = new BuyMoreStrategy("特惠",4,1); break; default: // statements_def break; } return strategy;};//普通var ItemNormalStrategy = function() { var self = this; self.type = "total"; self.description = "没有优惠";};ItemNormalStrategy.prototype = {};ItemNormalStrategy.prototype.constructor = ItemNormalStrategy;ItemNormalStrategy.prototype.desc = function() { return this.description;};ItemNormalStrategy.prototype.discount = function(money) { return money;};//买几送几var BuyMoreStrategy = function(description, buy, free) { var self = this; self.type = "total"; self.buy = buy; self.free = free; self.description = description + "买"+ buy + "送" + free;};BuyMoreStrategy.prototype = new ItemNormalStrategy();BuyMoreStrategy.prototype.constructor = BuyMoreStrategy;BuyMoreStrategy.prototype.desc = function() { return this.description;};BuyMoreStrategy.prototype.discount = function(item) { var give = item.num / (this.buy + this.free); var left = item.num % (this.buy + this.free); money = (give* this.buy + left)*item.price; return money;};/// 销售品种var SaleItem = function(name , price) { var self = this; self.name = name; self.price = price; self.num = 1; self.strategy = factory.getInstance(self.name);};SaleItem.prototype = {};SaleItem.prototype.constructor = SaleItem;SaleItem.prototype.clone = function() { var self = this; var cloneItem = new SaleItem(); cloneItem.name = self.name; cloneItem.price = self.price; cloneItem.num = self.num; cloneItem.strategy = self.strategy; return cloneItem;};SaleItem.prototype.count = function() { return this.price * this.num;};SaleItem.prototype.discountProcess = function(money) { if (this.strategy) { money = this.strategy.discount(this); }; return money;};SaleItem.prototype.discount = function() { return this.discountProcess(this.count());};/// 收银策略类var CashRegister = function() { var self = this; self.totalDiscountStrategy = new NormalStrategy(); self.arr = [];};CashRegister.prototype = {};CashRegister.prototype.constructor = CashRegister;//添加商品CashRegister.prototype.add = function(item, num) { var self = this; if (num) { item.num = num; }; self.arr.push(item);};//添加折扣策略CashRegister.prototype.setTotalDiscountStrategy = function(strategy) { this.totalDiscountStrategy = strategy;};//总计金额CashRegister.prototype.count = function() { var self = this; var totalMoney = 0; self.arr.forEach( function(item, index) { totalMoney += item.discount(); }); return totalMoney;};//折扣加入CashRegister.prototype.discountProcess = function(money) { var self = this; if (self.totalDiscountStrategy) { money = self.totalDiscountStrategy.discount(money); }; return money;};//折后金额CashRegister.prototype.discount = function() { var self = this; var totalMoney = self.count(); return self.discountProcess( totalMoney );};//结算清单CashRegister.prototype.print = function() { var self = this; console.log('-----------------------------'); console.log(' 购物清单 '); console.log(''); var totalMoney = 0; self.arr.forEach(function(item, index) { console.log(" %s : %s x %s = %s | ",item.name, item.price, item.num, item.count(),item.discount()); }); console.log('-----------------------------'); console.log(' 优惠使用 : ' + self.totalDiscountStrategy.desc()) console.log(' 购物合计 ' + self.count() +" -> "+ self.discount() ); console.log('');};/// 测试类var factory = new SaleItemStrategyFactory();var cashRegister = new CashRegister();cashRegister.setTotalDiscountStrategy(new PrecentOffStrategy("国庆",0.1));// cashRegister.setTotalDiscountStrategy(new GivebackStrategy("劳动节",500,300));// cashRegister.setTotalDiscountStrategy(new GivebackStrategy("劳动节",1000,500));cashRegister.add(new SaleItem("方便面",100),50);cashRegister.add(new SaleItem("菊花茶",10),50);cashRegister.print();