事件的理解

        public Form1()        {            InitializeComponent();            this.button1.Click += new EventHandler(btn1_click);            this.button2.Click += new EventHandler(btn1_click);            this.button2.Click += new EventHandler(btn2_click);        }        private void btn1_click(object sender, EventArgs e)        {            if (((Button)sender).Name == "button1")            {                MessageBox.Show("1");            }            else            {                MessageBox.Show("2");            }        }        private void btn2_click(object sender, EventArgs e)        {            MessageBox.Show("Hello!");        }