简单理解C#中的抽象工厂模式是什么概念！

    /// <summary> 
    /// 抽象工厂模式示例 
    /// </summary> 
    class AbstractFactory
    {
        //定义厨师的抽象工厂 
        public interface Chef
        {
            //这里定义厨师的公共操作 
            //返回抽象面条 
            Noodle MakeNoodle();
            //返回抽象米饭
            Rice MakeRice();
            //返回抽象面包 
            Bread MakeBread();
        }

        //定义北方厨师，实现厨师接口 
        class NorthChef : Chef
        {
            public Noodle MakeNoodle()
            {
                Console.WriteLine("\n制作北方面条...");
                Noodle noodle = new NorthNoodle();
                return noodle;
            }
            public Rice MakeRice()
            {
                Console.WriteLine("\n制作北方米饭...");
                Rice rice = new NorthRice();
                return rice;
            }
            public Bread MakeBread()
            {
                Console.WriteLine("\n正在制作北方面包..");
                Bread bread = new NorthBread(); return bread;
            }
        }
        //定义南方厨师，实现厨师接口 
        class SouthChef : Chef
        {
            public Noodle MakeNoodle()
            {
                Console.WriteLine("\n正在制作南方面条。。。");
                Noodle noodle = new SouthNoodle();
                return noodle;
            }
            public Rice MakeRice()
            {
                Console.WriteLine("\n正在制作南方米饭。。。");
                Rice rice = new SouthRice();
                return rice;
            }
            public Bread MakeBread()
            {
                Console.WriteLine("\n正在制作南方面包。。。");
                Bread bread = new SouthBread();
                return bread;
            }
        }

        //定义面条产品 
        public interface Noodle
        {
            //这里定义面条的公共操作 
        }
        class NorthNoodle : Noodle
        {
            public NorthNoodle()
            {
                Console.WriteLine("\n一碗地道的北方面条产生了");
            }
        }
        class SouthNoodle : Noodle
        {
            public SouthNoodle()
            {
                Console.WriteLine("\n一碗地道的南方面条产生了");
            }
        }
        //定义米饭产品 
        public interface Rice
        {
            //这里定义米饭的公共操作 
        }
        class NorthRice : Rice
        {
            public NorthRice()
            {
                Console.WriteLine("\n一碗地道的北方米饭产生了,真好吃");
            }
        }
        class SouthRice : Rice
        {
            public SouthRice()
            {
                Console.WriteLine("\n一碗地道的南方米饭产生了，真难吃");
            }
        }
        //定义面包 
        public interface Bread
        {
            //这里可以定义一些面包的公共操作 
        }
        class NorthBread : Bread
        {
            public NorthBread()
            {
                Console.WriteLine("\n一个地道的北方面包产生了");
            }
        }
        class SouthBread : Bread
        {
            public SouthBread()
            {
                Console.WriteLine("\n一个地道的南方面包产生了");
            }
        }
    }

       /// <summary> 
        /// 应用程序的主入口点。 
        /// </summary> 
        [STAThread] 
        static void Main(string[] args) 
        { 
            //针对接口编程，创建对象尽量返回上层接口，避免使用具体类 
            //下面隐藏了具体的创建各种面条，米饭和面包的过程 
            Chef northChef=new NorthChef(); 
            northChef.MakeNoodle(); 
            northChef.MakeRice(); 
            northChef.MakeBread(); 
            Chef southChef=new SouthChef(); 
            southChef.MakeBread(); 
            southChef.MakeNoodle(); 
            southChef.MakeRice(); 
            Console.ReadLine(); 
        }