c# 生成事件

public partial class Form1 : Form
    {
        public delegate void ActionEventHandler(object sender, ActionCancelEventArgs e);
        
 　　　　 public static event ActionEventHandler Action;

        public Form1()
        {
            
            InitializeComponent();
            button2.Click +=new EventHandler(button2_Click);
        }

        void button2_Click(object sender, EventArgs e)
        {
            ActionCancelEventArgs cancelEvent = new ActionCancelEventArgs();
            BusEntity busEntity = new BusEntity();
            OnAction(this, cancelEvent);
            if (cancelEvent.Cancel)
                label1.Text = cancelEvent.Message;
            else
                label1.Text = busEntity.TimeString;
        }

        protected void OnAction(object sender, ActionCancelEventArgs e)
        {
            if (Action != null)    //捕获空引用错误
                Action(sender, e);
        }

    }

    #region ActionCancelEventArgs 类
    public class ActionCancelEventArgs:CancelEventArgs 
    {
        string message = String.Empty;
        public ActionCancelEventArgs ():base(){}
        public ActionCancelEventArgs (bool cancel):base(cancel){}
        public ActionCancelEventArgs (bool cancel,string message):base(cancel)
        {
            this.message=message ;
        }
        public string Message
        {
            get{return message ;}
            set{message =value;}
        }

    }
    #endregion

    #region BusEntity 类
    public class BusEntity
    {
        string time = String.Empty;

        public BusEntity()
        {
            Form1.Action += new Form1.ActionEventHandler(Form1_Action);
        }

        private void Form1_Action(object sender, ActionCancelEventArgs e)
        {
            e.Cancel = !DoActions();
            if (e.Cancel)
                e.Message = "Wasn't the right time.";
        }

        private bool DoActions()
        {
            bool retVal = false;
            DateTime tm = DateTime.Now;

            if (tm.Second < 30)
            {
                time = "The time is " + DateTime.Now.ToLongTimeString();
                retVal = true;
            }
            else
                time = "";

            return retVal;
        }

        public string TimeString
        {
            get { return time; }
        }
    }
    #endregion