1、个人理解：将主类中的不定个数的、无序的额外处理划分为多个类，在客户端的时候能够对这些额外处理随意与主体类进行组织。

看一段代码（根据别人的Java代码改的）：卖饼，手抓饼和肉夹馍两种，可以添加的辅料有煎蛋、肉松等。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 装饰者模式2{    class Program    {        static void Main(string[] args)        {            Test test = new Test();            test.test();        }    }    public abstract class Pancake    {        public string desc = "我不是一个具体的饼";        public double price = 0;        public string GetDesc()        {            return desc;        }    }    /// 
    /// 手抓饼    /// 
    public class TornCake : Pancake    {        public TornCake()        {            desc = "手抓饼";            price = 4;        }    }    /// 
    /// 肉夹馍    /// 
    public class Roujiamo : Pancake    {        public Roujiamo()        {            desc = "肉夹馍";            price = 6;        }    }    /// 
    /// 作料    /// 
    public abstract class Condiment : Pancake    {        protected Pancake pancake;        public abstract string getDesc();        public abstract void AddCondiment(Pancake pancake);    }    /// 
    /// 煎蛋    /// 
    public class FiredEgg : Condiment    {        public FiredEgg()        {            price = 1;            desc = "煎蛋";        }        public override string getDesc()        {            return pancake.GetDesc() + ", 加煎蛋";        }        public override void AddCondiment(Pancake pancake)        {            this.pancake = pancake;            pancake.price += price;            pancake.desc += ", 加" + desc;        }    }    /// 
    /// 黄瓜    /// 
    public class Cucumber : Condiment    {        public Cucumber()        {            price = 2;            desc = "黄瓜";        }        public override string getDesc()        {            return pancake.GetDesc() + ", 加" + desc; ;        }        public override void AddCondiment(Pancake pancake)        {            this.pancake = pancake;            pancake.price += 2;            pancake.desc += ", 加黄瓜";        }    }    class Test    {        public void test()        {            Pancake pancake = new TornCake();            //手抓饼基础价            Console.WriteLine("描述:{0}, 基础价格:{1}", pancake.GetDesc(), pancake.price);            Pancake roujiamo = new Roujiamo();            //肉夹馍基础价            Console.WriteLine("描述:{0}, 基础价格:{1}", roujiamo.GetDesc(), roujiamo.price);            FiredEgg fireEgg = new FiredEgg();            Cucumber Cucumber = new Cucumber();            fireEgg.AddCondiment(roujiamo);            Cucumber.AddCondiment(roujiamo);            Console.WriteLine("描述:{0}, 价格:{1}", roujiamo.GetDesc(), roujiamo.price);            Console.ReadLine();        }    }}