C# 自定义事件

C＃自定义事件和java有所不同，涉及到委托。下面代码包括自定义事件从事件定义到事件触发和执行的全过程。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Timers;//using System.Timers;namespace EventTest{    //定义一个委托MessageHandler，可以看作是一个类。    public delegate void MessageHandler(string messageText);    class Connections    {//定义一个事件MessageArrive，是委托的实例        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)            {//触发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();    //将一个委托实例赋值给事件MessageArrive，参数为方法DisplayMessage,方法的参数要与委托类的参数一致。            connector.MessageArrive += new MessageHandler(displayor.DisplayMessage);            connector.Connect();            Console.ReadKey();        }    }    public class Display    {        public void DisplayMessage(string text)        {            Console.WriteLine(text);        }    }}