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js策略模式
策略模式定义了算法家族,分别封装起来,让他们之间可以相互替换,此模式让算法的变化不会影响到使用算法的客户。
先上C#版本:
namespace 策略模式 { //现金收取父类 abstract class CashSuper { //抽象方法:收取现金,参数为原价,返回为当前价 public abstract double acceptCash(double money); } }
namespace 策略模式 { //正常收费,继承CashSuper class CashNormal : CashSuper { public override double acceptCash(double money) { return money; } } }
namespace 策略模式 { //打折收费,继承CashSuper class CashRebate : CashSuper { private double moneyRebate = 1d; //初始化时,必需要输入折扣率,如八折,就是0.8 public CashRebate(string moneyRebate) { this.moneyRebate = double.Parse(moneyRebate); } public override double acceptCash(double money) { return money * moneyRebate; } } }
namespace 策略模式 { //返利收费,继承CashSuper class CashReturn : CashSuper { private double moneyCondition = 0.0d; private double moneyReturn = 0.0d; //初始化时必须要输入返利条件和返利值,比如满300返100,则moneyCondition为300,moneyReturn为100 public CashReturn(string moneyCondition, string moneyReturn) { this.moneyCondition = double.Parse(moneyCondition); this.moneyReturn = double.Parse(moneyReturn); } public override double acceptCash(double money) { double result = money; //若大于返利条件,则需要减去返利值 if (money >= moneyCondition) result = money - Math.Floor(money / moneyCondition) * moneyReturn; return result; } } }
namespace 策略模式 { //现金收取工厂 class CashContext { CashSuper cs = null; //根据条件返回相应的对象 public CashContext(string type) { switch (type) { case "正常收费": cs = new CashNormal(); break; case "满300返100": cs = new CashReturn("300", "100"); break; case "打8折": cs = new CashRebate("0.8"); break; } } public double GetResult(double money) { return cs.acceptCash(money); } } }
//调用: CashContext csuper = new CashContext(cbxType.SelectedItem.ToString()); totalPrices = csuper.GetResult(Convert.ToDouble(txtPrice.Text) * Convert.ToDouble(txtNum.Text)); lbxList.Items.Add("单价:" + txtPrice.Text + " 数量:" + txtNum.Text + " " + cbxType.SelectedItem + " 合计:" + totalPrices.ToString());
js模拟C#的策略模式:
//现金收取父类 var CashSuper = function(){}; CashSuper.prototype.acceptCash = function(money){ throw new Error(‘具体实现必须由子类重写‘); }; //正常收费,继承CashSuper var CashNormal = function(){}; CashNormal.prototype = new CashSuper(); CashNormal.prototype.acceptCash = function(money){ return money; }; //打折收费,继承CashSuper var CashRebate = function(moneyRebate){ this.moneyRebate = moneyRebate; }; CashRebate.prototype = new CashSuper(); CashRebate.prototype.acceptCash = function(money){ return money * this.moneyRebate; }; //返利收费,继承CashSuper var CashReturn = function(moneyCondition,moneyReturn){ this.moneyCondition = moneyCondition; this.moneyReturn = moneyReturn; }; CashReturn.prototype = new CashSuper(); CashReturn.prototype.acceptCash = function(money){ var result = money; ////若大于返利条件,则需要减去返利值 if (money >= this.moneyCondition) result = money - money / this.moneyCondition * this.moneyReturn; return result; }; //现金收取工厂 var CashContext = function(type){ this.cs; switch(type){ case ‘正常收费‘: this.cs = new CashNormal(); break; case ‘满300返100‘: this.cs = new CashReturn(300,100); break; case ‘打8折‘: this.cs = new CashRebate(0.8); break; } }; CashContext.prototype.getResult = function(money){ return this.cs.acceptCash(money); }; //调用: var type = ‘满300返100‘, //计算方式 price = 300, //单价 num = 2; //数量 var csuper = new CashContext(type); var totalPrices = csuper.getResult(price * num); alert(‘单价:‘ + price + ‘,数量:‘ + num + ‘,计算方式:‘ + type + ‘,合计:‘ + totalPrices);
js特性实现策略模式:
//策略对象 var cashStrategy = { //正常收费 cashNormal:function(){ return this.money; }, //打折收费 cashRebate:function(moneyRebate){ return this.money * moneyRebate; }, //返利收费 cashReturn:function(moneyCondition,moneyReturn){ var result = this.money; ////若大于返利条件,则需要减去返利值 if (this.money >= moneyCondition) result = this.money - this.money / moneyCondition * moneyReturn; return result; } }; //策略工厂 var CashContext = (function(){ //收取现金 var acceptCash = function(){ var type = [].shift.call(arguments), args = arguments; return function(money){ this.money = money; return cashStrategy[type].apply(this,args); }; }; var Fn = function(type){ this.cs = null; switch(type){ case ‘正常收费‘: this.cs = acceptCash(‘cashNormal‘); break; case ‘打8折‘: this.cs = acceptCash(‘cashRebate‘,0.8); break; case ‘满300返100‘: this.cs = acceptCash(‘cashReturn‘,300,100); break; } }; Fn.prototype.getResult = function(money){ return this.cs.call(this,money); }; return Fn; })(); //调用: var type = ‘满300返100‘, //计算方式 price = 300, //单价 num = 2; //数量 var csuper = new CashContext(type); var totalPrices = csuper.getResult(price * num); alert(‘单价:‘ + price + ‘,数量:‘ + num + ‘,计算方式:‘ + type + ‘,合计:‘ + totalPrices);
总结:js利用字典匹配就能轻松实现策略模式,由于他是动态语言不少模式是隐含的天生具有的,策略模式也是一个简单到不能算模式的模式。
js策略模式
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