学步园

 //简单工厂模式
    public abstract class pizza

    { }

    public class pizzaA : pizza

    { }

    public class pizzaB : pizza

    { }

    //现在这个pizza可以为许多需要pizza信息"客户"服务
    public class simplePizzaFactory

    {

        public pizza createPizza(string type)

        {

            pizza p = null;

            if (type == "A")

            {

                p = new pizzaA();

            }

            else if (type == "B")

            {

                p = new pizzaB();

            }

            return p;

        }

    }

    public class pizzaStore

    {

        simplePizzaFactory factory;

        public pizzaStore(simplePizzaFactory factory)

        {

            this.factory = factory;

        }

        public pizza OrderPizza(string type)

        {

            return factory.createPizza(type);

            //do somethingelse
        }

    }

    class Program

    {

        static void Main(string[] args)

        {

            simplePizzaFactory factory=new simplePizzaFactory();

            pizzaStore store = new pizzaStore(factory);

            store.OrderPizza("A");

            Console.Read();

        }

    }

  //设计模式原则：要依赖抽象，不要依赖具体类

    //工厂方法模式
    //定义了一个创建对象的接口，但由子类决定要实例化的类是哪一个
    //工厂方法让类把实例化推迟到子类
    public abstract class pizza
    { }
    public class pizzaA : pizza
    { }
    public class pizzaB : pizza
    { }
    //这是抽象创建者类，它定义了一个抽象的工厂方法
    //让子类实现此方法制造产品
    public abstract class pizzaStore
    {
        protected abstract pizza CreatePizza(string type);
        public pizza OrderPizza(string type)
        {
            pizza p =  CreatePizza(type);
            //do somethingelse   
            return p;
        }
    }
    public class StoreA : pizzaStore
    {
        protected override pizza CreatePizza(string type)
        {
            if (type == "A")
            {
                return new pizzaA();
            }
            else if (type == "B")
            {
                return new pizzaB();
            }
            else return null;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            pizzaStore storeA = new StoreA();
            storeA.OrderPizza("A");
            Console.Read();
        }
    }