设计模式：中介者模式（Mediator）

定   义：用一个中介对象来封装一系列对象的交互。中介者使各个对象不需要显示地相互作用，从而耦合松散，而且可以独立的改变他们之间的交互。

结构图：

Mediator类，抽象中介者类

  abstract class Mediator
    {
        public abstract void Send(string message, Colleague colleague);
    }

Colleague类，抽象同事类

  abstract class Colleague
    {
        protected Mediator mediator;

        public Colleague(Mediator mediator)
        {
            this.mediator = mediator;
        }
    }

ConcreteMediator类，具体中介者类：

  //具体中介者类
    class ConcreteMediator : Mediator
    {
        private ConcreteColleague1 colleague1;
        private ConcreteColleague2 colleague2;

        public ConcreteColleague1 Colleague1
        {
            set { colleague1 = value; }
        }

        public ConcreteColleague2 Colleague2
        {
            set { colleague2 = value; }
        }

        /// <summary>
        /// 重写发送消息方法，根据对象做出选择对象，做出判断
        /// </summary>
        /// <param name="message"></param>
        /// <param name="colleague"></param>
        public override void Send(string message, Colleague colleague)
        {
            if (colleague == colleague1)
            {
                colleague2.Notify(message);
            }
            else
            {
                colleague1.Notify(message);
            }

        }
    }

具体同事类：

//具体同事类1
    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("同事1得到消息：" + message);
        }
    }

    //具体同事类2
    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("同事2得到消息：" + message);
        }
    }

客户端调用：

 ConcreteMediator mediator = new ConcreteMediator();  //实例化一个中介者 

            ConcreteColleague1 colleague1 = new ConcreteColleague1(mediator);  //示例化同事1
            ConcreteColleague2 colleague2 = new ConcreteColleague2(mediator);  //实例化同事2

            //让中介者认识各个具体同事类对象
            mediator.Colleague1 = colleague1;
            mediator.Colleague2 = colleague2;

            //具体同事类对象发送的消息都是通过中介者转发
            colleague1.Send("吃饭了吗？");
            colleague2.Send("吃了，你呢？");

结果：