转：Mediator模式

using System;

using System.Linq;

using System.Text;



namespace DesignPatterns.Mediator

{

    //MediatorR

    abstract class AbstractChatroom

    {

        public abstract void Register(Participant participant);

        public abstract void Send(string from, string to, string message);

    }



    //ConcreteMediator

    class Chatroom : AbstractChatroom

    {

        private System.Collections.Hashtable participants = new System.Collections.Hashtable();

        public override void Register(Participant participant)

        {

            if (participants[participant.Name] == null)

            {

                participants[participant.Name] = participant;

            }

            participant.Chatroom = this;

        }

        public override void Send(string from, string to, string message)

        {

            Participant pto = (Participant)participants[to];

            if (pto != null)

            {

                pto.Receive(from, message);

            }

        }

    }

    /**********************************************************************************/

    //AbstractColleague

    class Participant

    {

        private Chatroom chatroom;

        private string name;



        //Constructor

        public Participant(string name)

        {

            this.name = name;

        }

        //Properties

        public string Name

        {

            get { return name; }

        }

        public Chatroom Chatroom

        {

            set { chatroom = value; }

            get { return chatroom; }



        }

        public void Send(string to, string message)

        {

            chatroom.Send(name, to, message);

        }

        public virtual void Receive(string from, string message)

        {

            Console.WriteLine("{0} to {1}:'{2}'", from, name, message);

        }

    }





    //ConcreteColleaguel

    class Beatle : Participant

    {

        //Constructor

        public Beatle(string name)

            : base(name)

        { }

        public override void Receive(string from, string message)

        {

            Console.Write("To a Beatle: ");

            base.Receive(from, message);

        }

    }



    //ConcreteColleague2

    class NonBeatle : Participant

    {

        //Constructor

        public NonBeatle(string name)

            : base(name)

        { }

        public override void Receive(string from, string message)

        {

            Console.Write("To a non-Beatle:");

            base.Receive(from, message);

        }

    }



    class Program

    {



        //客户端调用如下：

        static void Main(string[] args)

        {

            //create chatroom

            Chatroom chatroom = new Chatroom();

            //Create participants and register them

            Participant George = new Beatle("George");

            Participant Paul = new Beatle("Paul");

            Participant Ringo = new Beatle("Ringo");

            Participant John = new NonBeatle("John");

            Participant Yoko = new NonBeatle("Yoko");

            chatroom.Register(George);

            chatroom.Register(Paul);

            chatroom.Register(Ringo);

            chatroom.Register(John);

            chatroom.Register(Yoko);



            //chatting participants

            George.Send("Yoko", "你说错话了");

            Yoko.Send("George", "哪里说错了?");

            //Yoko.Send("John", "Hi John");

            //Paul.Send("Ringo", "All you need is love");

            //Ringo.Send("George", "My sweet Lord");

            //Paul.Send("John", "Can't buy me love");

            //John.Send("Yoko", "My sweet love");

            Console.ReadKey();

        }

    }

}