关于内容页修改母版页控件的问题，各位大神，帮帮忙

allin1987 2013-09-23 10:53:59

母版页 MasterPage.master

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="Test_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></title>

    <asp:ContentPlaceHolder id="head" runat="server">

    </asp:ContentPlaceHolder>

</head>

<body>

    <form id="form1" runat="server">

    <div>

        <asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server">

        

            <asp:Button ID="Button1" runat="server" Text="Button" />

        

        </asp:ContentPlaceHolder>

    </div>

    </form>

</body>

</html>

内容页 default.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/Test/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Test_Default" %>



<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">

</asp:Content>

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;



public partial class Test_Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        Button btn = this.Page.Master.FindControl("Button1") as Button;



        btn.Text = "Button2";

    }

}

我打开 default.aspx 的时候出现
Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 12: Button btn = this.Page.Master.FindControl("Button1") as Button;
Line 13:
Line 14: btn.Text = "Button2";
Line 15: }
Line 16: }

Source File: d:\home\olap\Test\Default.aspx.cs Line: 14

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
Test_Default.Page_Load(Object sender, EventArgs e) in d:\home\olap\Test\Default.aspx.cs:14
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +91
System.Web.UI.Control.LoadRecursive() +74
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2207

是哪里出问题了？？？

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allin1987 2013-09-23

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跟大括号 } 有什么关系吗？

insus 2013-09-23

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把16行移到14至18行之外。再试。

allin1987 2013-09-23

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顶一下都沉到第2页了

罗卜基斯 2013-09-23

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<asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server"> <asp:Button ID="Button1" runat="server" Text="Button" /> </asp:ContentPlaceHolder> 把标红色的部分放到ContentPlaceHolder的外部去，因为ContentPlaceHolder是针对内容页的

allin1987 2013-09-23

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谢谢啦，按你说的解决了，可是我想button这个控件在contentplaceholder1里面，应该怎么做啊？？？

insus 2013-09-23

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Insus.NET指的是下面三句：


<asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server">         
   <asp:Button ID="Button1" runat="server" Text="Button" />         
</asp:ContentPlaceHolder>