策略模式重构条件语句

通过策略模式来重构优化代码里面的switch/case分支代码。极大程度上提高了程序的扩展性。当然，如果分支比较多，每次都需要新增加一个类，这的确是有点麻烦，可以考虑使用反射来实现。 代码：

代码语言：javascript复制

namespace DP
{
    public enum State
    {
        Alaska,
        NewYork,
        Florida
    }

    public class CalculateShippingAmount 
    {
        public CalculateShippingAmount(IDictionary<State, IGetShippingAmount> dic) => _dic = dic;

        private IDictionary<State, IGetShippingAmount> _dic { get; set; }

        public decimal Calculate(State state) => _dic[state].GetAmount();
    }

    public interface IGetShippingAmount
    {
        decimal GetAmount();
    }

    #region 具体地址的实现
    // 具体
    public class GetAlaskaShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 15;
    }

    public class GetNewYorkShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 10;
    }

    public class GetFloridaShippingAmount : IGetShippingAmount
    {
        public decimal GetAmount() => 3;
    }
    #endregion

}

调用：

代码语言：javascript复制

#region 策略模式重构 switch...case...
        static void SwitchToStrategy()
        {
            var dic = new Dictionary<State, IGetShippingAmount>
            {
                {State.Alaska,  new GetAlaskaShippingAmount() },
                {State.Florida, new GetFloridaShippingAmount() },
                {State.NewYork, new GetNewYorkShippingAmount() }
            };

            var calculate = new CalculateShippingAmount(dic);
            var result = calculate.Calculate(State.Florida);
            Console.WriteLine($"{State.Florida.ToString()}返回{result}");
        }
        #endregion

参考：使用策略模式重构switch case 代码

public state 程序 反射 重构

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