中介者（Mediator）模式

           //实例一个 m 中介者。
            ConcreteMediator m = new ConcreteMediator();
            //实例 买家 卖商家，他们的中介者都是m
            ConcreteColleague1 c1 = new ConcreteColleague1(m);
            ConcreteColleague2 c2 = new ConcreteColleague2(m);

            m.Colleague1 = c1;
            m.Colleague2 = c2;

            //买家通过中介 传话给卖家
            c1.Send("买家说-房子120W卖不");
            //卖家通过中介回复
            c2.Send("卖家说-120W你卖我10套？");

            Console.ReadLine();


 /// <summary>
    /// Mediator 抽象中介者
    /// </summary>
    public abstract class Mediator
    {
        public abstract void Send(string message, Colleague colleague);
    }

    /// <summary>
    /// Colleague 抽象同事类
    /// </summary>
    public abstract class Colleague
    {
        protected Mediator mediator;
        /// <summary>
        /// 构造函数中 得到中介者
        /// </summary> 
        public Colleague(Mediator mediator)
        {
            this.mediator = mediator;
        } 
    }

    /// <summary>
    /// ConcreteMediator  具体中介者
    /// </summary>
    public class ConcreteMediator : Mediator
    {
        public ConcreteColleague1 Colleague1
        { get; set; }

        public ConcreteColleague2 Colleague2
        { get; set; }

        public override void Send(string message, Colleague colleague)
        {
            if (colleague == Colleague1)
            {
                Colleague2.Notify(message);
            }
            else
            {
                Colleague1.Notify(message);
            }
        }
    }

    /// <summary>
    /// 具体买家
    /// </summary>
    public class ConcreteColleague1 : Colleague
    {
        public ConcreteColleague1(Mediator mediator)
            : base(mediator)
        { }

        public void Send(string message)
        {
            mediator.Send(message, this);
        }

        public void Notify(string message)
        {
            Console.WriteLine("买家得到信息：" + message);
        }

    }

    /// <summary>
    /// 具体卖家
    /// </summary>
    public class ConcreteColleague2 : Colleague
    {
        public ConcreteColleague2(Mediator mediator)
            : base(mediator)
        { }

        public void Send(string message)
        {
            mediator.Send(message, this);
        }

        public void Notify(string message)
        {
            Console.WriteLine("卖家得到信息：" + message);
        }
    }