获取母版页的相关内容有两种方法

1 通过findcontrol找控件ID
 需要在此事件中~因为Page_load中时是先内容页加载然后才是母版页加载
    protected void Page_LoadComplete(object sender, EventArgs e)
    {
        Label2.Text = "现在时间是" + (Master.FindControl("Label1") as Label).Text;
        if (Request.QueryString["id"] == "dy")
        {
            (Master.FindControl("Image1") as Image).ImageUrl = "~/Images/ml0069.jpg";
        }
    }

2 通过强引用

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" Title="Untitled Page" %>
<%@ MasterType VirtualPath="~/MasterPage.master" %>