如果要访问的控件位于母版页的 ContentPlaceHolder 控件内部，必须首先获取对 ContentPlaceHolder 控件的引用，然后调用其 FindControl 方法获取对该控件的引用。
在内容页的Page_Load方法中设置嵌套模版页中label控件的Text属性：
首先获取主模版页的ContentPlaceHolder控件的引用，然后再获取要修改的控件的引用。
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ContentPlaceHolder pContent = (ContentPlaceHolder)Page.Master.Master.FindControl("Main");
if (pContent != null)
{
Label pLblTitle = (Label)pContent.FindControl("lbl_title");
if (pLblTitle != null)
{
pLblTitle.Text = "My Title";
}
}
}
}
附：
主模版页:
<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="Master_MasterPage" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:contentplaceholder id="Main" runat="server">
</asp:contentplaceholder>
</div>
</form>
</body>
</html>
嵌套模版页:
<%@ Master Language="C#" MasterPageFile="~/Master/Default.master" AutoEventWireup="true" CodeFile="Combines.master.cs" Inherits="Master_Combines" %>
<asp:content id="Content_combine" contentplaceholderid="Main" runat="server">
<asp:Label ID="lbl_title" runat="server" Text=""></asp:Label>
<asp:contentplaceholder id="Combine" runat="server">
</asp:contentplaceholder>
</asp:content>
内容页:
<%@ Page Language="C#" MasterPageFile="~/Master/Combines.master" AutoEventWireup="true" CodeFile="StationCombine.aspx.cs" Inherits="_Default" Title="Untitled Page" %>
<%@ MasterType VirtualPath="~/Master/Combines.master" %>
<asp:Content ID="Content1" ContentPlaceHolderID="Combine" Runat="Server">
</asp:Content>