行为型设计模式——中介者模式

用一个中介对象来封装一系列的对象交互，让各对象之间复杂的网状结构，变成简单的星型结构。中介者使各对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。

适用于

①一组对象以定义良好但是复杂的方式进行通信，产生的相互依赖关系结构混乱且难以理解。

②一个对象引用其他很多对象并且直接与这些对象通信，导致难以复用该对象。

③想定制一个分布在多个类中的行为，而又不想生成太多的子类。

类图如下

 

    internal class Program
    {
        static void Main(string[] args)
        {
            //创建中介者对象
            ConcreteMediator mediator = new ConcreteMediator();
            //创建同事类对象
            ConcreteColleague1 colleague1 = new ConcreteColleague1(mediator);
            ConcreteColleague2 colleague2 = new ConcreteColleague2(mediator);
            //中介者加入各个同事类，帮助它们交互
            mediator.SetConcreteColleague1(colleague1);
            mediator.SetConcreteColleague2(colleague2);

            colleague1.Send("同事你好呀");
            colleague2.Send("你好，你好，多多关照");
        }
    }

    /// <summary>
    /// 抽象中介者，用来定义传递消息抽象方法
    /// </summary>
    internal abstract class Mediator
    {
        public abstract void send(string message, Colleague colleague);
    }

    /// <summary>
    /// 抽象同事类
    /// </summary>
    internal abstract class Colleague
    {
        protected Mediator mediator;

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

    /// <summary>
    /// 具体同事类
    /// </summary>
    internal 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收到了消息：{message}");
        }
    }

    /// <summary>
    /// 具体同事类
    /// </summary>
    internal 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收到了消息：{message}");
        }
    }

    internal class ConcreteMediator : Mediator
    {
        private ConcreteColleague1 _colleague1;
        private ConcreteColleague2 _colleague2;

        public void SetConcreteColleague1(ConcreteColleague1 colleague1)
        {
            this._colleague1 = colleague1;
        }

        public void SetConcreteColleague2(ConcreteColleague2 colleague2)
        {
            this._colleague2 = colleague2;
        }
        public override void send(string message, Colleague colleague)
        {
            if (colleague == _colleague1)
            {
                _colleague2.Notify(message);
            }
            else if (colleague == _colleague2)
            {
                _colleague1.Notify(message);
            }
        }
    }