The Mediator design pattern defines an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.

簡單來說~ 中介者模式封裝一個類(Mediator)~ 將Mediator中的兩個對像進行互動~

換句話說~ Mediator促進兩個對象之間的鬆散~ 並允許使用它來改變它們兩個互動方式~

學習目標: 中介者模式的概念及實務

學習難度: ☆☆☆

using System;

namespace ConsoleApp1
{

    public abstract class Mediator //抽象中介者
    {
        public abstract void Send(string message, Player player); //抽象發送方法(訊息、Player)
    }

    public class ConcreteMediator : Mediator //實體中介者 (讓兩個對象物件進行交互)
    {
        ConcretePlayer1 player1; //實體玩家1

        ConcretePlayer2 player2; //實體玩家2

        public ConcretePlayer1 Player1 //建構實體玩家1
        {
            set { player1 = value; }
        }

        public ConcretePlayer2 Player2 //建構實體玩家2
        {
            set { player2 = value; }
        }

        public override void Send(string message, Player player) //建構實體發送方法
        {
            if (player == player1) //當player1傳訊息
            {
                player2.Notify(message); //player2收到通知
            }
            else
            {
                player1.Notify(message); //player1收到通知
            }
        }
    }



    public abstract class Player //抽象玩家
    {
        protected Mediator mediator; //定義中介者

        // Constructor

        public Player(Mediator mediator) //建構Player，讓Player能有中介者的parameter
        {
            this.mediator = mediator;
        }
    }

    public class ConcretePlayer1 : Player //實體玩家1
    {
        //建構實體玩家1，讓它能接受mediator，然後mediator的定義繼承抽象類

        public ConcretePlayer1(Mediator mediator) : base(mediator)
        {

        }

        //建構發送訊息的實體方法
        public void Send(string message)
        {
            mediator.Send(message, this); //從中介者送..
        }

        //建構接收訊息的實體方法
        public void Notify(string message)
        {
            Console.WriteLine("Player1 gets message: " + message);
        }
    }


    public class ConcretePlayer2 : Player //實體玩家2
    {
        //建構實體玩家2，讓它能接受mediator，然後mediator的定義繼承抽象類

        public ConcretePlayer2(Mediator mediator) : base(mediator)
        {

        }

        //建構發送訊息的實體方法
        public void Send(string message)
        {
            mediator.Send(message, this); //從中介者送..
        }

        //建構接收訊息的實體方法
        public void Notify(string message)
        {
            Console.WriteLine("Player2 gets message: " + message);
        }
    }


    public class MainProgram
    {
        public static void Main(string[] args)
        {
            //實體化中介者

            ConcreteMediator mediator = new ConcreteMediator();

            //實體化player1、player2，並將中介者塞入

            ConcretePlayer1 player1 = new ConcretePlayer1(mediator);

            ConcretePlayer2 player2 = new ConcretePlayer2(mediator);

            mediator.Player1 = player1;

            mediator.Player2 = player2;

            player1.Send("How are you?");

            player2.Send("Fine, thanks");
        }
    }
}

參考資料:

https://www.dofactory.com/net/mediator-design-pattern