关于事件的一个小例子

 public class SBY 
    {
        public delegate Boolean isSucceed(string message);

        public event isSucceed DeliverNewspaper;

        public Boolean GetResult(string dn) 
        {
            if(DeliverNewspaper!=null)
            {
                DeliverNewspaper(dn);
                return true;
            }
            else
            {
                return false;
            }
        }
    }
    /// <summary>
    /// 订阅器
    /// </summary>
    public class A
    {
        public Boolean GetNewspaper(string message) 
        {
            if (!string.IsNullOrEmpty(message))
            {
                Console.WriteLine("A GetData");
                return true;
            }
            else
            {
                Console.WriteLine("A don't GetData");
                return false;
            }
        }
    }

    public class B
    {
        public Boolean GetNewspaper(string message)
        {
            if (!string.IsNullOrEmpty(message))
            {
                Console.WriteLine("B GetData");
                return true;
            }
            else
            {
                Console.WriteLine("B don't GetData");
                return false;
            }
        }
    }

    public class C
    {
        public Boolean GetNewspaper(string message)
        {
            if (!string.IsNullOrEmpty(message))
            {
                Console.WriteLine("C GetData");
                return true;
            }
            else
            {
                Console.WriteLine("C don't GetData");
                return false;
            }
        }
    }

    public class TestEvent
    {
        static void Main(string[] args)
        {
            A a = new A();
            B b = new B();
            SBY sby = new SBY();
            sby.DeliverNewspaper += new SBY.isSucceed(a.GetNewspaper);
            sby.DeliverNewspaper += new SBY.isSucceed(b.GetNewspaper);
            sby.GetResult("send the newspaper");
            Console.ReadLine();
        }
    }