使用母版后 在内容页找内容页面上的控件

foreach (Control control in this.Controls[0].Controls)
            {
                if (control is HtmlForm)
                {
                    foreach (Control con in control.Controls)
                    {
                        if (con is ContentPlaceHolder)
                        {
                            foreach (Control ctrl in con.Controls)
                            {
                                   string id = ctrl.UniqueID;
                                    if (ctrl  is  Label)
                                    {
                                        this.TextBox1.Text = "abc";
                                    }
                            }
                        }
                    }
                }
            }