观察者模式

    public class Observer
    {
        public virtual void Update(string name)
        {

        }
    }

    public class ConcreteObeserver : Observer
    {
        public override void Update(string name)
        {
            Console.WriteLine(name+"发生改变触发观察者方法");
        }
    }

    public class Subject
    {
        public List<Observer> listObserver = new List<Observer>();
        private string name;
        public string Name
        {
            get { return name; }
            set
            {
                name = value;
                Modify(name);
            }
        }

        public void Add(Observer observer)
        {
            listObserver.Add(observer);
        }

        public void Modify(string name)
        {
            listObserver.ForEach(e=> {
                e.Update(name);
            });
        }
    }

    public class ConcreteSubject : Subject
    {
    }

    class Program
    {
        static void Main(string[] args)
        {
            Observer obeserver = new ConcreteObeserver();
            Subject subject = new ConcreteSubject();
            subject.Add(obeserver);
            subject.Name = "cys";
        }
    }