页面可以被看成各种控件组成的一个集合。在页面被初始化和加载过程中，可以遍历这些控件，找到特定的控件，或者改变某些控件的属性。
先看下面的一个例子：
script runat = " server " language = " C# " >
void
Page_Load(Object sender, EventArgs e)
{
foreach(Control c in Controls)
lblControlList.Text += c.ToString() + " - " + c.ID + "<br>";
}
</
script
>
<
html
>
<
head
>
</
head
>
<
body
>
<
b
>
A List of the Controls
in
the
<
code
>
Controls
</
code
>
Collection
</
b
><
br
>
<
asp:label runat
=
"
server
"
id
=
"
lblControlList
"
/>
<
p
>
<
form runat
=
"
server
"
>
What
'
s your name?
<
asp:textbox runat
=
"
Server
"
id
=
"
txtName
"
/>
</
form
>
</
body
>
</
html
>
这个例子列出页面上所有的控件,结果如下：
A List of the Controls in the
System.Web.UI.LiteralControl -
System.Web.UI.WebControls.Label - lblControlList
System.Web.UI.LiteralControl -
System.Web.UI.HtmlControls.HtmlForm -
System.Web.UI.ResourceBasedLiteralControl -
特别要注意的一点：以上代码没有列出ID=“txtName”的TextBox控件！因为这个TextBox控件包含在Form里面，是Form的一个子控件。而我们的代码 foreach(Control c in Controls) 只关心当前页面Controls的控件，至于子控件却未能涉及。（可以把这些控件理解成一个树状的层次关系）
页面Controls
/ | \ //foreach(Control c in Controls)
控件1 控件2 控件3 // 只判断控件1、2、3属于页面Controls
/ \ //而未涉及到下属子控件
子控件1 子控件2
为了真正做到遍历所有控件集，可以用递归的方法来实现：
<script runat="server" language="C#">
void IterateThroughChildren(Control parent)
{
foreach (Control c in parent.Controls)
{
lblControlList.Text += "<li>" + c.ToString() + "</li>";
if (c.Controls.Count > 0) // 判断该控件是否有下属控件。
{
lblControlList.Text += "<ul>";
IterateThroughChildren(c); //递归，访问该控件的下属控件集。
lblControlList.Text += "</ul>";
}
}
}
void Page_Load(Object sender, EventArgs e)
{
lblControlList.Text += "<ul>";
IterateThroughChildren(this);
lblControlList.Text += "</ul>";
}
</script>
<html>
<head>
</head>
<body>
<b>A List of the Controls in the
<code>Controls</code> Collection</b><br>
<asp:label runat="server" id="lblControlList" />
<p>
<form runat="server">
What's your name?
<asp:textbox runat="Server" id="txtName" />
</form>
</body>
</html>
以上代码运行结果如下：
先看下面的一个例子：
script runat = " server " language = " C# " >
void
Page_Load(Object sender, EventArgs e)
{ foreach(Control c in Controls) lblControlList.Text += c.ToString() + " - " + c.ID + "<br>"; }
</
script
>
<
html
>
<
head
>
</
head
>
<
body
>
<
b
>
A List of the Controls
in
the
<
code
>
Controls
</
code
>
Collection
</
b
><
br
>
<
asp:label runat
=
"
server
"
id
=
"
lblControlList
"
/>
<
p
>
<
form runat
=
"
server
"
>
What
'
s your name?
<
asp:textbox runat
=
"
Server
"
id
=
"
txtName
"
/>
</
form
>
</
body
>
</
html
>这个例子列出页面上所有的控件,结果如下：
A List of the Controls in the
Controls CollectionSystem.Web.UI.LiteralControl -
System.Web.UI.WebControls.Label - lblControlList
System.Web.UI.LiteralControl -
System.Web.UI.HtmlControls.HtmlForm -
System.Web.UI.ResourceBasedLiteralControl -
特别要注意的一点：以上代码没有列出ID=“txtName”的TextBox控件！因为这个TextBox控件包含在Form里面，是Form的一个子控件。而我们的代码 foreach(Control c in Controls) 只关心当前页面Controls的控件，至于子控件却未能涉及。（可以把这些控件理解成一个树状的层次关系）
页面Controls
/ | \ //foreach(Control c in Controls)
控件1 控件2 控件3 // 只判断控件1、2、3属于页面Controls
/ \ //而未涉及到下属子控件
子控件1 子控件2
为了真正做到遍历所有控件集，可以用递归的方法来实现：
<script runat="server" language="C#">
void IterateThroughChildren(Control parent) { foreach (Control c in parent.Controls) { lblControlList.Text += "<li>" + c.ToString() + "</li>"; if (c.Controls.Count > 0) // 判断该控件是否有下属控件。 { lblControlList.Text += "<ul>"; IterateThroughChildren(c); //递归，访问该控件的下属控件集。 lblControlList.Text += "</ul>"; } } } void Page_Load(Object sender, EventArgs e){ lblControlList.Text += "<ul>"; IterateThroughChildren(this); lblControlList.Text += "</ul>"; }</script><html><head></head><body> <b>A List of the Controls in the <code>Controls</code> Collection</b><br> <asp:label runat="server" id="lblControlList" /> <p> <form runat="server"> What's your name? <asp:textbox runat="Server" id="txtName" /> </form></body></html> 以上代码运行结果如下：A List of the Controls in the Controls Collection
- System.Web.UI.LiteralControl
- System.Web.UI.WebControls.Label
- System.Web.UI.LiteralControl
- System.Web.UI.HtmlControls.HtmlForm
- System.Web.UI.LiteralControl
- System.Web.UI.WebControls.TextBox
- System.Web.UI.LiteralControl
- System.Web.UI.ResourceBasedLiteralControl
这下TextBox控件真的露出了庐山真面目。
本文转自today4king博客园博客，原文链接：http://www.cnblogs.com/jinzhao/archive/2007/10/19/930120.html，如需转载请自行联系原作者
