ASP.NET 采用MasterPage 后的控件组织结构

你可以在Page指令页设置启用Trace单页面跟踪，或者在Web.config中再启用全局跟踪，就可以看到Control Tree了。

 采用MasterPage后的页面结构如下：

            //Page  --ASP.about_aspx
            //    Master Page   --ASP.site_master
            //        (Master page markup and controls)
            //        ContentPlaceHolder    --HeadContent
            //            Content page markup and server controls
            //            (Master page markup and controls)
            //        ContentPlaceHolder    --MainContent
            //            Content page markup and server controls
            //            (Master page markup and controls)

无论我们用FindControl查找控件，或者是添加控件，一定是添加到ContenPlaceHolder内部的！

下面代码实现了动态添加控件以及两种查找控件的方法。

       //BMK FindControlRecursive
        /// <summary>
        /// 迭代遍历控件，查找子控件
        /// </summary>
        /// <param name="rootControl">包含控件的容器</param>
        /// <param name="controlIDToBeSEEK">要查找的控件的ID</param>
        /// <returns></returns>
        private Control FindControlRecursive(Control rootControl, string controlIDToBeSEEK)
        {
            if (rootControl.ID == controlIDToBeSEEK)
                return rootControl;

            foreach (Control control in rootControl.Controls)
            {
                Control controlToReturn = FindControlRecursive(control, controlIDToBeSEEK);
                if (controlToReturn != null)
                    return controlToReturn;
            }
            return null;
        }



        //再有Masterpage 的时候，控件必须加到ContentPlaceHolder内
        //要查找控件，也必须ContentPlaceHolder内FindControl，无论层次怎样，总能得到有效结果
        protected void Button1_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < 5; i++)
            {
               TextBox  txtDynamicAdded = new TextBox();
               txtDynamicAdded.ID = "txt" + i.ToString();
                txtDynamicAdded.Text = "Hello,World!";
                //可视状态,否则PostBack后动态添加的控件会不见
                ViewState[txtDynamicAdded.ID] = true;
                this.Master.FindControl("MainContent").Controls.Add(txtDynamicAdded);
            }

            Control ctrlFindbutton = FindControlRecursive(this, "Button1");
            if (ctrlFindbutton != null)
            {
                Button btnFind = (Button)ctrlFindbutton;
                btnFind.Text = "find" + DateTime.Now.ToString("T");
            }

            //如何才能访问MainContent呢
            Control cc = this.Master.FindControl("MainContent").FindControl("Button1");


            //Page  --ASP.about_aspx
            //    Master Page   --ASP.site_master
            //        (Master page markup and controls)
            //        ContentPlaceHolder    --HeadContent
            //            Content page markup and server controls
            //            (Master page markup and controls)
            //        ContentPlaceHolder    --MainContent
            //            Content page markup and server controls
            //            (Master page markup and controls)

        }