阅读此文请先查看网页教学网的：ASP.NET入门教程:Web服务器控件，简单讲述了Web服务器控件的使用方法。
PlaceHolder 控件用于为代码添加的控件预留空间。在页控件层次结构中为以编程方式添加的控件保留位置。
注释：PlaceHolder 不会产生任何可见的输出（仅仅是网页上其它控件的容器）。
| 属性 | 描述 | .NET |
|---|---|---|
| runat | 规定控件是服务器。必须设置为 "server"。 | 1.0 |
AccessKey, Attributes, BackColor, BorderColor, BorderStyle, BorderWidth, CssClass, Enabled, Font, EnableTheming, ForeColor, Height, IsEnabled, SkinID, Style, TabIndex, ToolTip, Width
AppRelativeTemplateSourceDirectory, BindingContainer, ClientID, Controls, EnableTheming, EnableViewState, ID, NamingContainer, Page, Parent, Site, TemplateControl, TemplateSourceDirectory, UniqueID, Visible
<asp:PlaceHolder
EnableTheming="True|False"
EnableViewState="True|False"
ID="string"
OnDataBinding="DataBinding event handler"
OnDisposed="Disposed event handler"
OnInit="Init event handler"
OnLoad="Load event handler"
OnPreRender="PreRender event handler"
OnUnload="Unload event handler"
runat="server"
SkinID="string"
Visible="True|False"
/>
备注：将 PlaceHolder 控件用作容器，从而将动态添加的服务器控件存储到网页中。PlaceHolder 控件不产生任何可见的输出，仅用作网页上其他控件的容器。您可以使用 Control.Controls 集合在 PlaceHolder 控件中添加、插入或移除控件。
下面的示例演示如何将 Web 服务器控件添加到 PlaceHolder 控件中。
Visual Basic
<%@ Page Language="VB" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
Sub Page_Load(Sender As Object, e As EventArgs)
Dim myButton As HtmlButton = New HtmlButton()
myButton.InnerText = "Button 1"
PlaceHolder1.Controls.Add(myButton)
myButton = New HtmlButton()
myButton.InnerText = "Button 2"
PlaceHolder1.Controls.Add(myButton)
myButton = New HtmlButton()
myButton.InnerText = "Button 3"
PlaceHolder1.Controls.Add(myButton)
myButton = New HtmlButton()
myButton.InnerText = "Button 4"
PlaceHolder1.Controls.Add(myButton)
End Sub
</script>
</head>
<body>
<form runat="server">
<h3>PlaceHolder Example</h3>
<asp:PlaceHolder id="PlaceHolder1"
runat="server"/>
</form>
</body>
</html>
C#
<%@ Page Language="C#" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
void Page_Load(Object sender, EventArgs e)
{
HtmlButton myButton = new HtmlButton();
myButton.InnerText = "Button 1";
PlaceHolder1.Controls.Add(myButton);
myButton = new HtmlButton();
myButton.InnerText = "Button 2";
PlaceHolder1.Controls.Add(myButton);
myButton = new HtmlButton();
myButton.InnerText = "Button 3";
PlaceHolder1.Controls.Add(myButton);
myButton = new HtmlButton();
myButton.InnerText = "Button 4";
PlaceHolder1.Controls.Add(myButton);
}
</script>
</head>
<body>
<form runat="server">
<h3>PlaceHolder Example</h3>
<asp:PlaceHolder id="PlaceHolder1"
runat="server"/>
</form>
</body>
</html>