34、面向对象设计模式之工厂模式——简单工厂模式与工厂方法模式比较

用下面的例子比较：

　　

using System;

namespace LearnObject
{
    public class LeiFeng
    {
        public void Sweep()
        {
            Console.WriteLine("扫地");
        }
        public void Wash()
        {
            Console.WriteLine("洗衣服");
        }

        public void BuyRice()
        {
            Console.WriteLine("买米");
        }
    }
    public class Undergrade : LeiFeng
    {

    }

    public class Volunteer : LeiFeng
    {

    }

    public class SimpleLeiFengFactory
    {
        public static LeiFeng CreateLeiFeng(string typeName)
        {
            LeiFeng result = null;
            switch (typeName)
            {
                case "学雷锋的大学生":
                    result = new Undergrade();
                    break;
                case "社区志愿者":
                    result = new Volunteer();
                    break;
            }
            return result;
        }
    }
    public interface IFactory
    {
        LeiFeng CreateLeiFeng();
    }
    public class UndergradeFactory : IFactory
    {
        public LeiFeng CreateLeiFeng()
        {
            return new Undergrade();
        }
    }
    public class VolunteerFactory : IFactory
    {
        public LeiFeng CreateLeiFeng()
        {
            return new Volunteer();
        }
    }
    public class Program
    {
        public static void Main(string[] args)
        {
            // 不使用工厂实例化
            LeiFeng zhangsan = new Undergrade();
            zhangsan.BuyRice();
            zhangsan.Sweep();
            zhangsan.Wash();
            LeiFeng student1 = new Undergrade();
            student1.BuyRice();
            student1.Sweep();
            student1.Wash();

            //简单工厂实例化
            LeiFeng studentA = SimpleLeiFengFactory.CreateLeiFeng("学雷锋的大学生");
            studentA.BuyRice();
            studentA.Sweep();
            studentA.Wash();

            LeiFeng volunteer = SimpleLeiFengFactory.CreateLeiFeng("社区志愿者");
            volunteer.BuyRice();
            volunteer.Sweep();
            volunteer.Wash();

            //工厂方法实例化
            IFactory factory = new UndergradeFactory();
            LeiFeng student = factory.CreateLeiFeng();
            student.BuyRice();
            student.Sweep();
            student.Wash();
            factory = new VolunteerFactory();
            LeiFeng volunteer1 = factory.CreateLeiFeng();
            volunteer1.BuyRice();
            volunteer1.Sweep();
            volunteer1.Wash();
        }
    }
}