【设计模式】工厂方法（FactoryMethod）模式

看不见PPT的请自行解决DNS污染问题。

 相关类的代码：

namespace FactoryPatternConsole.Model
{
    public class Address
    {
        public string CountryCode { get; set; }
    }
}

namespace FactoryPatternConsole.Model
{
    public class Order
    {
        public decimal TotalCost { get; set; }
        public decimal WeightInKG { get; set; }
        public string CourierTrackingId { get; set; }
        public Address DispatchAddress { get; set; }
    }
}

namespace FactoryPatternConsole.Model
{
    public interface IShippingCourier
    {
        string GenerateConsignmentLabelFor(Address address);
    }
}

namespace FactoryPatternConsole.Model
{
    public class DHL : IShippingCourier
    {
        public string GenerateConsignmentLabelFor(Address address)
        {
            return "DHL-XXXX-XXXX-XXXX";
        }
    }
}

namespace FactoryPatternConsole.Model
{
    public class RoyalMail:IShippingCourier
    {
        public string GenerateConsignmentLabelFor(Address address)
        {
            return "RM-XXXX-XXXX-XXXX";
        }
    }
}

using FactoryPatternConsole.Model;

namespace FactoryPatternConsole.Factory
{
    public static class UKShippingCourierFactory
    {
        public static IShippingCourier CreateShippingCourier(Order order)
        {
            if (order.TotalCost > 100 || order.WeightInKG > 5)
            {
                return new DHL();
            }
            else
            {
                return new RoyalMail();
            }
        }
    }
}

using FactoryPatternConsole.Factory;
using FactoryPatternConsole.Model;

namespace FactoryPatternConsole.Service
{
    public class OrderService
    {
        public void Dispatch(Order order)
        {
            IShippingCourier shippingCourier = UKShippingCourierFactory.CreateShippingCourier(order);

            order.CourierTrackingId = shippingCourier.GenerateConsignmentLabelFor(order.DispatchAddress);
        }
    }
}

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 测试用代码：

using FactoryPatternConsole.Model;
using FactoryPatternConsole.Service;
using System;

namespace FactoryPatternConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            OrderService service = new OrderService();
            foreach (Order order in GetOrders())
            {
                service.Dispatch(order);
                Console.WriteLine(string.Format("TotalCost:{0}, WeightInKG:{1}, CourierTrackingId:{2}",
                    order.TotalCost, order.WeightInKG, order.CourierTrackingId));
            }
            Console.ReadLine();
        }

        public static Order[] GetOrders()
        {
            return new Order[] {
                new Order() 
                { 
                    TotalCost = 100,
                    WeightInKG = 5,
                    DispatchAddress = new Address() { CountryCode = "CN" },
                },
                new Order() 
                { 
                    TotalCost = 100.1m,
                    WeightInKG = 4,
                    DispatchAddress = new Address() { CountryCode = "CN" },
                },
                new Order() 
                { 
                    TotalCost = 100,
                    WeightInKG = 5.1m,
                    DispatchAddress = new Address() { CountryCode = "CN" },
                },
            };
        }
    }
}

---

执行结果：