C# 事件

    class PubEventArgs : EventArgs
    {
        private readonly string m_magazineName;
        private readonly DateTime m_pubDate;
        public PubEventArgs(string magazineName,DateTime pubDate)
        {
            m_magazineName = magazineName;
            m_pubDate = pubDate;
        }
        public string magazineName
        {
            get { return m_magazineName; }
        }
        public DateTime pubDate
        {
            get { return m_pubDate; }
        }
    }

    class Publisher  //出版社
    {
        public delegate void PubComputerEventHandler(object sender, PubEventArgs e);
        public delegate void PubLifeEventHandler(object sender, PubEventArgs e);
        public event PubComputerEventHandler PubComputer; //电脑杂志事件
        public event PubLifeEventHandler PubLife;         //生活杂志事件

        protected virtual void OnPubComputer(PubEventArgs e)  //受保护的方法
        {
            PubComputerEventHandler handler = PubComputer;  //定义临时的委托
            if (handler != null)
            {
                handler(this, e);
            }
        }

        protected virtual void OnPubLife(PubEventArgs e)
        {
            PubLifeEventHandler handler = PubLife;
            if (handler != null)
            {
                handler(this, e);
            }
        }

        public void issueComputer(string magezineName,DateTime pubDate)
        {
            Console.WriteLine(pubDate.ToShortDateString() + "发行了" + magezineName);
            OnPubComputer(new PubEventArgs(magezineName, pubDate));  //这里调用保护的虚拟方法。
        }

        public void issueLife(string magezineName, DateTime pubDate)
        {
            Console.WriteLine(pubDate.ToShortDateString() + "发行了" + magezineName);
            OnPubLife(new PubEventArgs(magezineName, pubDate));
        }

    }
    class Pubscriber  //订阅者
    {
        private string name;
        public Pubscriber(string name)
        {
            this.name = name;
        }
        public void Receive(object sender, PubEventArgs e)
        {
            Console.WriteLine("{0} {1} 已经收到{2}", e.pubDate.ToString(), name, e.magazineName);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Publisher pub = new Publisher();
            Pubscriber zs = new Pubscriber("张三");
            pub.PubComputer += new Publisher.PubComputerEventHandler(zs.Receive); //添加事件 用户张三订阅电脑杂志
            Pubscriber ls = new Pubscriber("李四");
            pub.PubComputer += new Publisher.PubComputerEventHandler(ls.Receive); //添加事件 用户李四订阅电脑杂志
            pub.PubLife += new Publisher.PubLifeEventHandler(ls.Receive);     //添加事件 用户李四订阅生活杂志
            pub.issueComputer("电脑杂志",Convert.ToDateTime("2014-01-01"));
            pub.issueLife("生活杂志",Convert.ToDateTime("2014-01-01"));
            Console.WriteLine();
            Console.WriteLine("一年后。。。");
            pub.PubComputer -= new Publisher.PubComputerEventHandler(ls.Receive);  //移除事件 用户李四取消订阅电脑杂志
            pub.issueComputer("电脑杂志", Convert.ToDateTime("2014-02-01"));
            pub.issueLife("生活杂志", Convert.ToDateTime("2014-02-01"));
            Console.ReadKey();
        }
    }