责任链模式

    public abstract class Handler
    {
        private Handler _nextHandler;

        public Response HandleMessage(Request request)
        {
            Response response = null;
            //判断是否是自己的处理级别
            if (request.GetRequestLevel().Equals(this.GetHandlerLevel()))
            {
                response = Echo(request);
            }
            else
            {
                //不属于自己的处理级别，判断是否有下一个处理者
                if (_nextHandler != null)
                {
                    response = _nextHandler.HandleMessage(request);
                }
            }

            return response;
        }

        //设置下一个处理者
        public void SetNextHandler(Handler handler)
        {
            _nextHandler = handler;
        }
        //每个处理者都必须实现处理任务
        protected abstract Response Echo(Request request);
        //每个处理者都有一个处理级别
        protected abstract Level GetHandlerLevel();
    }

    public class ConcreteHandler1 : Handler
    {
        /// <summary>
        /// 定义自己的业务逻辑
        /// </summary>
        /// <param name="request"></param>
        /// <returns></returns>
        protected override Response Echo(Request request)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// 设置自己的处理级别
        /// </summary>
        /// <returns></returns>
        protected override Level GetHandlerLevel()
        {
            throw new NotImplementedException();
        }
    }

    public class ConcreteHandler2 : Handler
    {
        /// <summary>
        /// 定义自己的业务逻辑
        /// </summary>
        /// <param name="request"></param>
        /// <returns></returns>
        protected override Response Echo(Request request)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// 设置自己的处理级别
        /// </summary>
        /// <returns></returns>
        protected override Level GetHandlerLevel()
        {
            throw new NotImplementedException();
        }
    }

    public class ConcreteHandler3 : Handler
    {
        /// <summary>
        /// 定义自己的业务逻辑
        /// </summary>
        /// <param name="request"></param>
        /// <returns></returns>
        protected override Response Echo(Request request)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// 设置自己的处理级别
        /// </summary>
        /// <returns></returns>
        protected override Level GetHandlerLevel()
        {
            throw new NotImplementedException();
        }
    }

    /// <summary>
    /// 请求与处理级别
    /// </summary>
    public class Level
    {

    }

    /// <summary>
    /// 定义一个请求
    /// </summary>
    public class Request
    {
        public Level GetRequestLevel()
        {
            return null;
        }
    }

    /// <summary>
    /// 处理者返回的数据
    /// </summary>
    public class Response
    {
    }

    /// <summary>
    /// 场景类
    /// </summary>
    class Program
    {

        private static void Main(string[] args)
        {
            //声明所有的处理节点 
            Handler handler1 = new ConcreteHandler1();

            Handler handler2 = new ConcreteHandler2();

            Handler handler3 = new ConcreteHandler3();
            //设置链中的阶段顺序
            handler1.SetNextHandler(handler2);

            handler2.SetNextHandler(handler3);
            //提交请求，返回结果
            handler1.HandleMessage(new Request());

            Console.ReadKey();
        }

    }