HelloWorld簡單例子如下：此例子好好體會下繼承 is a和組合 has a的異同。

using System;
using System.Runtime.InteropServices;

namespace TestEnviroment
{
    class Program
    {
        static void Main(string[] args)
        {
            BaseClass ins = new Ins();
            ins = new Before(ins);
            ins = new After(ins);
            ins.Do();
            Console.ReadLine();
        }
    }
    
 
public abstract class BaseClass
    {
        public abstract void Do();
    }
    public class Ins : BaseClass
    {
        public override void Do()
        {
            Console.Write("World");     //底層行為
        }
    }
    public abstract class BaseDecorator: BaseClass
    {
        public BaseClass baseClass;
        
 
public BaseDecorator(BaseClass baseClass)
        {
            this.baseClass = baseClass;
        }
    }
    public class After : BaseDecorator
    {
        public After(BaseClass baseClass) : base(baseClass) { }
        public override void Do()
        {
            base.baseClass.Do();
            Console.Write(
 
" Jack");     //擴充套件區
        }
    }
    public class Before: BaseDecorator
    {
        public Before(BaseClass baseClass) : base(baseClass) { }
        public override void Do()
        {
            Console.Write("Hello ");     //擴充套件區
            base.baseClass.Do();
        }
    }
}

下面是綜合例子：