接口+配置文件+反射实现充值优惠

网吧举办优惠活动，要求灵活可扩展。分为满50加10，满100加30，充120%，充150%

appconfig

    <add key="无" value="NoDiscount"/>
    <add key="满50送10" value="ManFifty"/>
    <add key="满100送30" value="ManOneHundred"/>
    <add key="充120%" value="Charge120"/>
    <add key="充150%" value="Charge150"/>

接口+实现类

 /**
     * 优惠力度，接口+实现类
     * 
     */
    public interface IDiscount
    {
        decimal getRecharge(decimal recharge);
    }
    public class NoDiscount : IDiscount
    {
        public decimal getRecharge(decimal recharge)
        {
            return recharge;
        }
    }
    public class ManFifty : IDiscount
    {
        public decimal getRecharge(decimal recharge)
        {
            return recharge + 10;
        }
    }
   
    public class ManOneHundred : IDiscount
    {
        public decimal getRecharge(decimal recharge)
        {
            return recharge + 30;
        }
    }
    public class Charge120 : IDiscount
    {
        public decimal getRecharge(decimal recharge)
        {
            return recharge * decimal.Parse("1.2");
        }
    }
    public class Charge150 : IDiscount
    {
        public decimal getRecharge(decimal recharge)
        {
            return recharge * decimal.Parse("1.5");
        }
    }

B层

 //配置文件+反射计算优惠后的充值金额
 string discount = list["discount"].ToString();
 string preferential = System.Configuration.ConfigurationManager.AppSettings[discount];
 IDiscount idiscount = (IDiscount)Assembly.Load("BLL").CreateInstance("BLL."+preferential);
 
decimal recharge= idiscount.getRecharge(Convert.ToDecimal(list["rechargeCash"].ToString()));

U层

list.Add("rechargeCash", cbCash.Text.Trim());

 string[] keys= System.Configuration.ConfigurationManager.AppSettings.AllKeys;
            for (int i =2; i < keys.Length; i++)
            {
                string key = keys[i];
                cbType.Items.Add(key);
            }
            cbType.SelectedIndex = 0;