CSharp: Factory Method Pattern in donet 6

    /// <summary>
    /// The Product declares the interface, which is common to all objects 
    /// that can be produced by the creator <see cref="Restaurants.Common.Restaurant"/> and its subclasses.
    /// 工厂方法模式 Factory Method - Creational Pattern
    /// </summary>
    public interface IMeal
    {

        /// <summary>
        /// 
        /// </summary>
        void ShowDescription();
    }

    /// <summary>
    /// The Creator class declares the factory method that returns new product objects.
    /// 工厂方法模式 Factory Method - Creational Pattern
    /// </summary>
    public abstract class Restaurant
    {
        /// <summary>
        /// The factory method that returns new product objects.
        /// It’s important that the return type of this method matches the product interface.
        /// You can declare the factory method as abstract to force all subclasses to implement their own versions of the method.
        /// As an alternative, the base factory method can return some default product type.
        /// </summary>
        /// <returns>Meal.</returns>
        public abstract IMeal PrepareMainCourse();

        /// <summary>
        /// Note, despite its name, product creation is not the primary responsibility of the creator. 
        /// Usually, the creator class already has some core business logic related to products.
        /// The factory method helps to decouple this logic using the concrete product classes.
        /// </summary>
        public void OrderDailySpecial()
        {
            Console.WriteLine("Geovin Du 要饮料:苏打水");

            var mainCourse = PrepareMainCourse();
            mainCourse.ShowDescription();
        }
    }

   /// <summary>
    /// Concrete products are different implementations of the product interface <see cref="IMeal"/>.
    /// </summary>
    public class GreenSalad : IMeal
    {

        /// <summary>
        /// 
        /// </summary>
        public void ShowDescription()
        {
            Console.WriteLine("涂聚文叫单：蔬菜沙拉——有生菜、黄瓜和青橄榄");
        }
    }

    /// <summary>
    /// Concrete products are different implementations of the product interface <see cref="IMeal"/>.
    /// </summary>
    public class Hamburger : IMeal
    {

        /// <summary>
        /// 
        /// </summary>
        public void ShowDescription()
        {
            Console.WriteLine("Geovin Du叫单：汉堡-加牛肉，伍斯特沙司和奶酪。再来一份中餐：鸳鸯火锅.");
        }
    }

   /// <summary>
    /// Concrete creators override the base factory method so it returns a different type of product.
    /// 工厂方法模式 Factory Method - Creational Pattern
    /// </summary>
    public class VegetarianRestaurant : Restaurant
    {

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public override IMeal PrepareMainCourse()
        {
            return new GreenSalad();
        }
    }

    /// <summary>
    /// Concrete creators override the base factory method so it returns a different type of product.
    /// 工厂方法模式 Factory Method - Creational Pattern
    /// </summary>
    public class FastFoodRestaurant : Restaurant
    {

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public override IMeal PrepareMainCourse()
        {
            return new Hamburger();
        }
    }

    /// <summary>
    /// 工厂方法模式 Factory Method - Creational Pattern
    /// 
    /// </summary>
    public class Executor : PatternExecutor
    {

        /// <summary>
        /// 
        /// </summary>
        public override string Name => "工厂方法模式 Factory Method - Creational Pattern";
        /// <summary>
        /// 
        /// </summary>
        public override void Execute()
        {
            Restaurant restaurant = InitializeRestaurant();

            restaurant.OrderDailySpecial();
        }
        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private Restaurant InitializeRestaurant()
        {
            // This is usually stored within some configuration
            var choosenType = typeof(FastFoodRestaurant).FullName;
            choosenType = typeof(VegetarianRestaurant).FullName;
            return Assembly.GetExecutingAssembly().CreateInstance(choosenType) as Restaurant;
        }
    }

调用：

            Console.WriteLine("Hello, Geovin Du! 学习 .net 6 ");
            //Geovin.Du.DuEmail.EmailExecutor.Execute();
            //Geovin.Du.DuStock.StockExecutor.Execute();
            // Geovin.Du.DuShoppingCart.ShoppingCartExecutor.Execute();
            //Geovin.Du.DuNullObject.SmartphoneApplicationExecutor.Execute();
           
            Geovin.Du.DuFactoryMethod.Executor ex = new Geovin.Du.DuFactoryMethod.Executor();
            ex.Execute();

输出：

Hello, Geovin Du! 学习 .net 6
Geovin Du 要饮料:苏打水
涂聚文叫单：蔬菜沙拉——有生菜、黄瓜和青橄榄