C# 事件（2）

下边Demo如果是在vs2012 下运行需要进入调试模式，并且用合理的速度调试一遍才能正常运行出结果。

namespace ConsoleApplication2{    public delegate void MessageHanlder(Connection source, MessageArrivedEventArgs e);    public class Connection    {        public event MessageHanlder MessageArried;        private Timer pollTimer;        public string name { get; set; }        public Connection()        {            pollTimer = new Timer(700);            pollTimer.Elapsed += new ElapsedEventHandler(CheckForMsg);        }        public void Connect()        {            pollTimer.Start();        }        public void DisConnect()        {            pollTimer.Stop();        }        private static Random random = new Random();        void CheckForMsg(object sources, ElapsedEventArgs e)        {            Console.WriteLine("Checking for new messages");            if ((random.Next(9) == 0) && (MessageArried != null))//使用了委托语法，但语法略有不同，其含义为“事件是否有订阅者？”如果没有订阅者，MessageArrived就是null，也就不会引发事件。            {                MessageArried(this, new MessageArrivedEventArgs("Hello Mum!"));            }        }    }    class Display    {        public void DisplayMsg(Connection source, MessageArrivedEventArgs e)        {            Console.WriteLine("message arrived from:{0}", source.name);            Console.WriteLine("message Text:{0}", e.Message);        }    }    class Program    {        static void Main(string[] args)        {            Connection conn1 = new Connection();            conn1.name = "First conneciton";            Connection conn2 = new Connection();            conn2.name = "second connection";            Display display = new Display();            conn1.MessageArried += new MessageHanlder(display.DisplayMsg);//注册事件            conn2.MessageArried += delegate(Connection source, MessageArrivedEventArgs e)//匿名方式注册事件            {                Console.WriteLine("dddddddddd message arrived from:{0}", source.name);                Console.WriteLine("dddddddddd message Text:{0}", e.Message);            };            conn2.Connect();            conn1.Connect();            Console.ReadKey();        }    }    public class MessageArrivedEventArgs : EventArgs    {        private string message;        public string Message        {            get { return message; }        }        public MessageArrivedEventArgs()        {            message = "No message sent";        }        public MessageArrivedEventArgs(string newmsge)        {            message = newmsge;        }    }}