C# 事件

標籤：

/// <summary>    /// 事件數目據    /// </summary>    internal sealed class NewMailEventArgs : EventArgs    {        private readonly String m_from, m_to, m_subject;        public NewMailEventArgs(String from, String to, String subject)        {            m_from = from; m_to = to; m_subject = subject;        }        /// <summary>        /// 寄件者        /// </summary>        public String From { get { return m_from; } }        /// <summary>        /// 收件者        /// </summary>        public String To { get { return m_to; } }        /// <summary>        /// 標題        /// </summary>        public String Subject { get { return m_subject; } }    }    internal class MailManager    {        private EventHandler<NewMailEventArgs> m_NewMail;        // 事件屬性        public event EventHandler<NewMailEventArgs> NewMail        {            add            {                m_NewMail += value;            }            remove            {                m_NewMail -= value;            }        }        protected virtual void OnNewMail(NewMailEventArgs e)        {             //EventHandler<NewMailEventArgs> temp =            // Interlocked.CompareExchange(ref m_NewMail, null, null);            //if (temp != null) temp(this, e);            if (m_NewMail != null)            {                m_NewMail.Invoke(this,e);            }        }        /// <summary>        /// 類比新郵件        /// </summary>        /// <param name="from"></param>        /// <param name="to"></param>        /// <param name="subject"></param>        public void SimulateNewMail(String from, String to, String subject)        {            NewMailEventArgs e = new NewMailEventArgs(from, to, subject);            OnNewMail(e);        }    }    /// <summary>    /// 傳真    /// </summary>    internal sealed class Fax    {        public Fax(MailManager mm)        {                 mm.NewMail += FaxMsg;        }        private void FaxMsg(Object sender, NewMailEventArgs e)        {            Console.WriteLine("傳真郵件資訊:");            Console.WriteLine("   From={0}, To={1}, Subject={2}",               e.From, e.To, e.Subject);        }        public void Unregister(MailManager mm)        {            mm.NewMail -= FaxMsg;        }    }    internal sealed class Pager    {        public Pager(MailManager mm)        {            mm.NewMail += SendMsgToPager;        }        private void SendMsgToPager(Object sender, NewMailEventArgs e)        {            Console.WriteLine("發送郵件到呼叫器:");            Console.WriteLine("   From={0}, To={1}, Subject={2}", e.From, e.To, e.Subject);        }        public void Unregister(MailManager mm)        {            mm.NewMail -= SendMsgToPager;        }    }

用戶端：

  static void Main(string[] args)        {            // Construct a MailManager object            MailManager mm = new MailManager();            // Construct a Fax object passing it the MailManager object            Fax fax = new Fax(mm);            // Construct a Pager object passing it the MailManager object            Pager pager = new Pager(mm);            // Simulate an incoming mail message            mm.SimulateNewMail("Jeffrey", "Kristin", "I Love You!");            // Force the Fax object to unregister itself with the MailManager            fax.Unregister(mm);            // Simulate an incoming mail message            mm.SimulateNewMail("Jeffrey", "Mom & Dad", "Happy Birthday.");        }

 

C# 事件