using System;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.Form["btn2"] != null)
        {
            Response.Write("S");
        }

        Button btn1 = new Button();
        btn1.Text = "button1";
        this.form1.Controls.Add(btn1);
        btn1.Click += (o, ev) =>
            {
                Button btn2 = new Button();
                btn2.Text = "button2";
                btn2.ID="btn2";
                this.form1.Controls.Add(btn2);
            };
    }
}

------解决方案--------------------
C# code

 

private void button1_Click(object sender, EventArgs e)
        {
            Button newbtn = new Button();
            newbtn.Name = "new";
            newbtn.Text = "new";
            newbtn.Size = new Size(100, 50);
            newbtn.Location = new Point(newbtn.Location.X+200,newbtn.Location.Y+100);
            newbtn.Visible = true;
            this.Controls.Add(newbtn);
            newbtn.Click += new EventHandler(newbtn_click);
            
        }
        private void newbtn_click(object sender, EventArgs e)
        {
            MessageBox.Show("success");
        }

------解决方案--------------------

取消button注册的事件
C# code

        private void button1_Click(object sender, EventArgs e)
        {
            button2.Click -= new EventHandler(button2_Click); //取消button2注册的事件
        }

        private void button2_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Hello");
        }
//先点击button2里会弹出"Hello"对话框的;若先点button1,再点button2就不会弹出"Hello"对话框了