C# 接口事件 测试

using System;
using System.Collections.Generic;
using System.Text;

namespace ImplementInterfaceEvents
{
    interface IDrawingObject
    {
        event EventHandler ShapeChanged;
    }

    public class MyEventArgs : EventArgs
    {
        private string dispalyMsg;

        public string DispalyMsg
        {
            get { return dispalyMsg; }
        }

        public MyEventArgs()
            : this(string.Empty)
        {
        }

        public MyEventArgs(string msg)
        {
            this.dispalyMsg = msg;
        }
    }

    public class Shape : IDrawingObject
    {
        public event EventHandler ShapeChanged;

        public void ChangeShape()
        {
            Console.WriteLine("Do something here before the event…");
            OnShapeChanged(new MyEventArgs("hello"));
            Console.WriteLine("or do something here after the event .");
        }

        protected virtual void OnShapeChanged(MyEventArgs e)
        {
            if (ShapeChanged != null)
            {
                ShapeChanged(this, e);
            }
        }

    }

    public class TestDemo
    {
        static void Main(string[] args)
        {

            Shape s = new Shape();
            s.ShapeChanged += new EventHandler(s_ShapeChanged);
            s.ChangeShape();
            Console.ReadLine();
        }

        static void s_ShapeChanged(object sender, EventArgs e)
        {
            Console.WriteLine(((MyEventArgs)e).DispalyMsg);
            Console.WriteLine("s_ShapeChanged");
        }

    }
}