/// <summary>
 /// 重写发送信息的方法,根据所传对象发送到指定对象消息
 /// </summary>
 /// <param name="message"></param>
 /// <param name="colleague"></param>
 public override void Send(string message, Colleague colleague)
 {
     if (colleague == colleague1)
     {
         //同事1给同事2消息
         colleague2.Notify(message);
     }
     else
     {
         //同事2给同事1消息
         colleague1.Notify(message);
     }
 }
 /// <summary>
 /// 得到同事对象和发送消息的抽象方法
 /// </summary>
 /// <param name="message"></param>
 /// <param name="colleague"></param>
 public abstract void Send(string message, Colleague colleague);
 /// <summary>
 /// 得到同事对象和发送消息的抽象方法
 /// </summary>
 /// <param name="message"></param>
 /// <param name="colleague"></param>
 public abstract void Send(string message, Colleague colleague);