FindControl的使用方法

Control.FindControl (String)：在当前的命名容器中搜索带指定 id参数的服务器控件。（有点类似javascript中的getElementById(string)）

简单的例子：

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

<div>

<asp:TextBox ID="TextBox1" runat="server">TextBox</asp:TextBox>

<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />

<br />

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

</div>

</form>

如果需要获得页面中的"TextBox1",代码中可以使用this.TextBox1来引用，这里我们使用FindControl:

protected void Button1_Click(object sender, EventArgs e)

{

//Control c = this.FindControl("TextBox1");

//TextBox tb= (TextBox)c;

//FindControl返回的是一个Control类型的控件，需要强制类型转化成TextBox类型

TextBox tb=(TextBox)this.FindControl("TextBox1");

this.Label1.Text = tb.Text;   
    }

当TextBox1放到其他控件里应该怎么查找呢？

<div>

<asp:Panel ID="Panel1" runat="server" Height="50px" ;125px">

<asp:TextBox ID="TextBox1" runat="server">TextBox</asp:TextBox>

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />

</asp:Panel>

</div>

当TextBox1放到Panel里，似乎没什么影响 TextBox tb=(TextBox)this.FindControl("TextBox1")，

当查看生存页面的HTML代码是发现，TextBox的ID并没有改变，所以可以获得TextBox1。

<div>

<div id="Panel1" style="height:50px;;">

<input name="TextBox1" type="text" value="TextBoxdsd" id="TextBox1" />

<span id="Label1">TextBoxdsd</span>

<input type="submit" name="Button1" value="Button" id="Button1" />

</div>

</div>

当TextBox1放到DataGrid中

<asp:DataGrid ID="dg1" runat="server" OnSelectedIndexChanged="dg1_SelectedIndexChanged">

<Columns>

<asp:TemplateColumn>

<ItemTemplate>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</ItemTemplate>

</asp:TemplateColumn>

<asp:ButtonColumn CommandName="Select" Text="选择"></asp:ButtonColumn>

</Columns>

</asp:DataGrid>

这时候this.FindControl("TextBox1")==null,无法获得TextBox1,查看生成页面HTML发现，页面有多个

<input name="dg1$ctl02$TextBox1" type="text" id="dg1_ctl02_TextBox1" />

<input name="dg1$ctl03$TextBox1" type="text" id="dg1_ctl03_TextBox1" />

TextBox1隐藏了，给DataGrid添加选择列，通过以下方法获得被选择行的TextBox1

protected void dg1_SelectedIndexChanged(object sender, EventArgs e)

{

Control c = this.dg1.Items[this.dg1.SelectedIndex].FindControl("TextBox1");

//Control c = this.dg1.SelectedItem.FindControl("TextBox1");

TextBox tb = (TextBox)c;

tb.Text = "TextBox";

}

protected void dg1_EditCommand(object source, DataGridCommandEventArgs e)

{

TextBox tb = (TextBox)e.Item.FindControl("TextBox1");

this.Label1.Text = tb.Text.ToString();

}

如果是在DataGrid的页眉和页脚：

((TextBox)this.dg1.Controls[0].Controls[0].FindControl("TextBoxH")).Text = "Head";

((TextBox)this.dg1.Controls[0].Controls[this.dg1.Controls[0].Controls.Count -1].FindControl("TextBoxF")).Text = "Footer";

TextBox1在Repeater中

<asp:Repeater ID="Repeater1" runat="server" DataSourceID="SqlDataSource1" OnItemCommand="Repeater1_ItemCommand">

<ItemTemplate>

<asp:TextBox ID="TextBox1" runat="server" Text=""></asp:TextBox><%#DataBinder.Eval(Container.DataItem,"ProductName")%>

<asp:Button ID="btn"OnClick="btn_click" runat="server" Text="dddd" /><br />

</ItemTemplate>

</asp:Repeater>

通过按钮来获得TextBox1:

protected void btn_click(object sender, EventArgs e)

{

//获得按钮

Button btn = (Button)sender;

TextBox tb = (TextBox)btn.Parent.FindControl("TextBox1");

tb.Text = "Text";

}

或者

foreach (RepeaterItem item in this.Repeater1.Items)

{

((TextBox)item.FindControl("TextBox1")).Text = "Text2";

}

自定义控件里的TextBox1

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

引用<uc1:WebUserControl ID="WebUserControl1" runat="server" />

获取TextBox1:

((TextBox)this.WebUserControl1.FindControl("TextBox1")).Text = "userc";

模板页访问页面TextBox1

//模板页的TextBox1

TextBox tbM = (TextBox)this.FindControl("TextBox1");

//页面中的TextBox1

TextBox tbC = (TextBox)this.FindControl("ContentPlaceHolder1").FindControl("TextBox1");

tbC.Text = tbM.Text;

页面使用模板页的TextBox1

//模板页的TextBox1

TextBox tbM = (TextBox)Master.FindControl("TextBox1");

//本页面的TextBox1

//错误的方法：TextBox tbC = (TextBox)this.FindControl("TextBox1");

TextBox tbC = (TextBox)Master.FindControl("ContentPlaceHolder1").FindControl("TextBox1");

tbM.Text = tbC.Text.ToString();