动态获得控件名（在带有master page结构下）

[stevenhzhang]

我现在主代码是这样

<%@ Page Language="VB" MasterPageFile="~/Admin/MasterPage.master" AutoEventWireup="false" CodeFile="Page1.aspx.vb" Inherits="Page1" title="Page 1" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:Label ID="Label1" runat="server" />
<asp:Label ID="Label2" runat="server" />
<asp:Label ID="Label3" runat="server" />
<asp:Label ID="Label4" runat="server" />
</asp:Content>

后台代码

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        For i = 1 To 3
            CType(Me.FindControl("Label" & CStr(i)), Label).Text = i
        Next
    End Sub

但是在运行的时候找不到Label1, Label2

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.

但是

[stevenhzhang]

自己解决了。

方法一：直接写

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        For i = 1 To 3
            CType(Me.Master.FindControl("ContentPlaceHolder1").FindControl("Label" & CStr(i)), Label).Text = i
        Next
    End Sub

方法二：在外面套了一个Panel

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:Panel ID="PagePanel" runat="server">
<asp:Label ID="Label1" runat="server" />
<asp:Label ID="Label2" runat="server" />
<asp:Label ID="Label3" runat="server" />
<asp:Label ID="Label4" runat="server" />
</asp:Panel>
</asp:Content>

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        For i = 1 To 3
            CType(PagePanel.FindControl("Label" & CStr(i)), Label).Text = i
        Next
    End Sub

[阿非]

使用 TryCast 代替 CType

[tzs2304]

[随风落梦]

由于是母板页，所以会不会Label1这样出现啊？你运行页面后查看下原代码，看看Id变啥了