设计模式 - 22）中介者模式

使用中介模式，大家通过往中介发消息，和从中介接受消息。从而避免了多个端之间的耦合。就像你看房，你不需要联系各个房东，你只需要联系中介，由中介去联系各个房东和各个租客。

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

abstract class Colleague
{
    protected Mediator mediator;

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

    public abstract void Notify(string message);
}

class ConcreteColleague : Colleague
{        
    public string Name { get; set; }
 
    public ConcreteColleague(Mediator mediator) : base(mediator) { }

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

    public override void Notify(string message)
    {
        Console.WriteLine(string.Format("{0}收到消息:{1}", Name, message));
    }
}

class ConcreteMediator : Mediator
{
    IList<Colleague> _colleagueList = new List<Colleague>();

    public void AddColleague(Colleague colleague)
    {
        _colleagueList.Add(colleague);
    }

    public void RemoveColleague(Colleague colleague)
    {
        _colleagueList.Remove(colleague);
    }

    public override void Send(string message, Colleague colleague)
    {
        foreach (Colleague coll in _colleagueList)
        {
            if (coll == colleague) continue;

            coll.Notify(message);
        }
    }
}

ConcreteMediator ccm = new ConcreteMediator();
ConcreteColleague ccA = new ConcreteColleague(ccm);
ccA.Name = "中国";

ConcreteColleague ccB = new ConcreteColleague(ccm);
ccB.Name = "巴基斯坦";

ConcreteColleague ccC = new ConcreteColleague(ccm);
ccC.Name = "孟加拉国";

ccm.AddColleague(ccA);
ccm.AddColleague(ccB);
ccm.AddColleague(ccC);

ccA.Send("我们是好朋友啊");

巴基斯坦收到消息:我们是好朋友啊
孟加拉国收到消息:我们是好朋友啊