C# 自訂事件

C＃自訂事件和java有所不同，涉及到委託。下面程式碼封裝括自訂事件從事件定義到事件觸發和執行的全過程。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Timers;//using System.Timers;namespace EventTest{    //定義一個委託MessageHandler，可以看作是一個類。    public delegate void MessageHandler(string messageText);    class Connections    {//定義一個事件MessageArrive，是委託的執行個體        public event MessageHandler MessageArrive;        private Timer pollTimer;        private static Random random = new Random();        public Connections()        {            this.pollTimer = new Timer();            pollTimer.Elapsed += new ElapsedEventHandler(Display);        }        public void Connect()        {            pollTimer.Start();        }        public void Disconnect()        {            pollTimer.Stop();        }        public void Display(object source, ElapsedEventArgs e)        {            Console.WriteLine("New Message Coming");            if (random.Next(9) == 0 && MessageArrive != null)            {//觸發MessageArrive事件                MessageArrive("New Message Arrived, And has been handled successfully");            }        }        static void Main(string[] args)        {            Connections connector = new Connections();            Display displayor = new Display();    //將一個委託執行個體賦值給事件MessageArrive，參數為方法DisplayMessage,方法的參數要與委託類的參數一致。            connector.MessageArrive += new MessageHandler(displayor.DisplayMessage);            connector.Connect();            Console.ReadKey();        }    }    public class Display    {        public void DisplayMessage(string text)        {            Console.WriteLine(text);        }    }}