namespace RefactoringLib.SwitchToStrategy.Before{    public class ClientCode    {        public decimal CalculateShipping()        {            ShippingInfo shippingInfo = new ShippingInfo();            return shippingInfo.CalculateShippingAmount(State.Alaska);        }    }    public enum State    {        Alaska,        NewYork,        Florida    }    public class ShippingInfo    {        public decimal CalculateShippingAmount(State shipToState)        {            switch (shipToState)            {                case State.Alaska:                    return GetAlaskaShippingAmount();                case State.NewYork:                    return GetNewYorkShippingAmount();                case State.Florida:                    return GetFloridaShippingAmount();                default:                    return 0m;            }        }        private decimal GetAlaskaShippingAmount()        {            return 15m;        }        private decimal GetNewYorkShippingAmount()        {            return 10m;        }        private decimal GetFloridaShippingAmount()        {            return 3m;        }    }}

 

namespace RefactoringLib.SwitchToStrategy.End{    public class ClientCode    {        public decimal CalculateShipping()        {            ShippingInfo shippingInfo = new ShippingInfo();            return shippingInfo.CalculateShippingAmount(State.Alaska);        }    }    public enum State    {        Alaska,        NewYork,        Florida    }    public class ShippingInfo    {        public IDictionary
      
        ShippingCalculatons { get; set; }        public ShippingInfo()        {            ShippingCalculatons = new Dictionary
       
                     {                { State.Alaska, new AlaskaShippingCalculation() },                { State.NewYork, new NewYorkShippingCalculation() },                { State.Florida, new FloridaShippingCalculation() }            };        }        public decimal CalculateShippingAmount(State state)        {            return ShippingCalculatons[state].Calculate();        }    }    public interface IShippingCalculaton    {        decimal Calculate();    }    public class AlaskaShippingCalculation : IShippingCalculaton    {        public decimal Calculate()        {            return 15m;        }    }    public class NewYorkShippingCalculation : IShippingCalculaton    {        public decimal Calculate()        {            return 10m;        }    }    public class FloridaShippingCalculation : IShippingCalculaton    {        public decimal Calculate()        {            return 5m;        }    }}
       
      

 

 参考：