Unity实现设计模式——中介者模式

用一个中介者对象来封装一系列的对象交互，中介者使各对象不需要显示地相互引用，从而使其松散耦合，而且可以独立地改变它们之间的交互。

这里使用一个生活中的例子来介绍中介者模式，比如当我们在一个聊天大厅进行聊天，每个人可以根据名字给对应的人发送消息，那么A人一定要持有其余人的名字信息吗，要是突然有新的人加入进来需要告知所有人多了个人吗，显然这样的设计方式非常繁琐，我们可以转化为以中介者为中心的星型结构，极大的解耦。

1.AbstractChatroom（The ‘Mediator’ abstract class）

聊天大厅的抽象基类

    abstract class AbstractChatroom
    {
        public abstract void Register(Participant participant);
        public abstract void Send(string from, string to, string message);
    }

2.Chatroom（The ‘ConcreteMediator’ class）

    class Chatroom : AbstractChatroom
    {
        private Dictionary<string, Participant> _participants =
          new Dictionary<string, Participant>();

        public override void Register(Participant participant)
        {
            if (!_participants.ContainsValue(participant))
            {
                _participants[participant.Name] = participant;
            }

            participant.Chatroom = this;
        }

        public override void Send( string from, string to, string message)
        {
            Participant participant = _participants[to];

            if (participant != null)
            {
                participant.Receive(from, message);
            }
        }
    }

3.Participant（The ‘AbstractColleague’ class）

聊天的参与者基类

    class Participant
    {
        private Chatroom _chatroom;
        private string _name;

        // Constructor
        public Participant(string name)
        {
            this._name = name;
        }

        // Gets participant name
        public string Name
        {
            get { return _name; }
        }

        // Gets chatroom
        public Chatroom Chatroom
        {
            set { _chatroom = value; }
            get { return _chatroom; }
        }

        // Sends message to given participant
        public void Send(string to, string message)
        {
            _chatroom.Send(_name, to, message);
        }

        // Receives message from given participant
        public virtual void Receive(string from, string message)
        {
            Debug.Log(from + " to " + Name + ": '" + message + "'");
        }
    }

4.Beatle（ A ‘ConcreteColleague’ class）

聊天参与者子类

    class Beatle : Participant
    {
        // Constructor
        public Beatle(string name)
          : base(name)
        {
        }

        public override void Receive(string from, string message)
        {
            Debug.Log("To a Beatle: ");
            base.Receive(from, message);
        }
    }

5.NonBeatle（A ‘ConcreteColleague’ class）

聊天参与者子类

    class NonBeatle : Participant
    {
        // Constructor
        public NonBeatle(string name)
          : base(name)
        {
        }

        public override void Receive(string from, string message)
        {
            Debug.Log("To a non-Beatle: ");
            base.Receive(from, message);
        }
    }

6.测试

    public class MediatorExample1 : MonoBehaviour
    {
        void Start()
        {
            // 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 Beatle("John");
            Participant Yoko = new NonBeatle("Yoko");

            chatroom.Register(George);
            chatroom.Register(Paul);
            chatroom.Register(Ringo);
            chatroom.Register(John);
            chatroom.Register(Yoko);

            // Chatting participants
            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");

        }
    }