设计模式 中介者模式(Mediator Pattern)

意图

　　用一个中介对象来封装一系列的对象交互。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。

适用性

　　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。

　　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。

　　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。 

结构图

　　

Code

// Mediator


/* Notes:
 * Consider a mediator as a hub, which objects that need to talk -
 * but do not wish to be interdependent - can use. 
 */
 
namespace Mediator_DesignPattern
{
    using System;

    class Mediator 
    {
        private DataProviderColleague dataProvider;
        private DataConsumerColleague dataConsumer;
        public void IntroduceColleagues(DataProviderColleague c1, DataConsumerColleague c2)
        {
            dataProvider = c1;
            dataConsumer = c2;            
        }
        
        public void DataChanged()
        {
            int i = dataProvider.MyData;
            dataConsumer.NewValue(i);
        }
    }

    class DataConsumerColleague 
    {
        public void NewValue(int i)
        {
            Console.WriteLine("New value {0}", i);
        }
    }

    class DataProviderColleague
    {
        private Mediator mediator;
        private int iMyData=0;
        public int MyData 
        {
            get 
            {
                return iMyData;
            }
            set 
            {
                iMyData = value;
            }
        }
        public DataProviderColleague(Mediator m)
        {
            mediator = m;
        }

        public void ChangeData()
        {
            iMyData = 403;

            // Inform mediator that I have changed the data
            if (mediator != null)
                mediator.DataChanged();    
        }        
    }

    /// <summary>
    ///    Summary description for Client.
    /// </summary>
    public class Client
    {
        public static int Main(string[] args)
        {            
            Mediator m = new Mediator();
            DataProviderColleague c1 = new DataProviderColleague(m);
            DataConsumerColleague c2 = new DataConsumerColleague();
            m.IntroduceColleagues(c1,c2);

            c1.ChangeData();

            return 0;
        }
    }
}