302班

    protected void btnCancle_Click(object sender, EventArgs e)
    {
        Set_Controls(this.Page);//调用
    }
//首先定义一个方法
    private void Set_Controls(Control ctl)
    {
        //当控件没有子控件时  
        if (!ctl.HasControls())
        {
            switch (ctl.GetType().ToString())
            {
                case "System.Web.UI.WebControls.Label":
                    break;
                case "System.Web.UI.WebControls.TextBox":
                    ((TextBox)ctl).Text="";
                    break;
                case "System.Web.UI.WebControls.DropDownList":
                    ((DropDownList)ctl).SelectedIndex = -1;
                    break;
            }
        }
        else   //当控件有子控件时  
        {

            int i = 0;
            while (i < ctl.Controls.Count)
            {
                Set_Controls(ctl.Controls[i]);
                i++;
            }
        }
    }