protected void ImageButton_delete_Click(object sender, ImageClickEventArgs e)
{
ImageButton imageButton = sender as ImageButton;
string id = imageButton.CommandArgument;
Class clazz = new Class();
clazz.Id = id;
ClassBLL classBLL = new ClassBLL();
classBLL.delete(clazz);
Response.Write("<script>alert('删除成功！');location.href='showClasses.aspx';</script>");
}