Observer 观察者模式

namespace DemoObserver
{
    public interface IAccountObservre
    {
        void Update(userAccount args);
    }



    public class Emailer : IAccountObservre
    {
        public void Update(UserAccountArgs args)
        {
            //....
            string toAddress = args.ToAddress;
        }
    }

    public class Mobile : IAccountObservre
    {
        public void Update(UserAccountArgs args)
        {
            //....
            string mobileNumber = args.MobileNumber;
        }
    }


    public abstract class Subject
    {
        ArrayList<IAccountObservre> observerList = new ArrayList<IAccountObservre>();


        protected virtual void Notify(UserAccount args)
        {
            foreach (IAccountObservre observer in observerList)
            {
                observer.Update(args);
            }
        }


        public void AddObserver(IAccountObservre observer)
        {
            observerList.Add(observer);
        }

        public void RemoveObserver(IAccountObservre observer)
        {
            observerList.Remove(observer);
        }
    }

    public class BankAccount : Subject
    {

        public void Withdraw(int data)
        {
            //....
            UserAccountArgs args = new UserAccountArgs();
            //....
            Notify(args);

        }
    }
}