控件
关于.net的自定义控件
一：谈到自定义控件，就不得不说@Register（这玩艺具体怎么翻译我也不知道，只好用E文，嘿嘿）。
1.@Register语法格式：
<%@Register tagprefix="tagprefix" Namespace="namespace" Assembly="assembly"%> or
<%@Register tagprefix="tagprefix" TagName="tagname" src="pathname"%>
2.属性：
tagprefix:把别名和名称空间连接在一起
tagname:把类名和名称空间连接在一起
Namespace:哈哈，顾名思义把名称空间和tagprefix连接在一起
src:用户自定义控件的路径
Assembly:我们与tagprefix联系的名称
注：Assembly的名称不能包含已存在的文件名
（E文好的可看随机文档）
二：自定义控件的建立(.ascx)
.net的自定义控件和asp里的.inc文件非常相似（包括功能也是），我们可以在里面使用html,更可以
连接数据库等等，哎我怎么越说越不明白，还是看看例子吧：
第一个例子只是html文件：
Header.ascx
<table cellspacing="0" cellpadding="0" width="100%" border="0">
<tr>
<td colspan="2" background="images/grid_background.gif" nowrap>
<table cellspacing="0" cellpadding="0" width="100%" border="0">
<tr>
<td colspan="2">
<img src=http://www.163design.net/n/a/"images/most_secretive_place.gif">
</td>
<td align="right" nowrap>
<table cellpadding="0" cellspacing="0" border="0">
<tr valign="top">
<td align="center" width="65">
<a href="Login.aspx" class="SiteLinkBold"><img src=http://www.163design.net/n/a/"images/sign_in.gif" border="0">
Sign In</a>
</td>
<td align="center" width="75">
<a href="OrderList.aspx" class="SiteLinkBold"><img src=http://www.163design.net/n/a/"images/account.gif" border="0">
Account</a>
</td>
<td align="center" width="55">
<a href="ShoppingCart.aspx" class="SiteLinkBold"><img src=http://www.163design.net/n/a/"images/cart.gif" border="0">
Cart</a>
</td>
<td align="center" width="65">
<a href="InstantOrder.asmx" class="SiteLinkBold"><img src=http://www.163design.net/n/a/"images/services.gif" border="0">
Services</a>
</td>
<tr>
</table>
</td>
<td width="10">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td colspan="2" nowrap>
<form method="post" action="SearchResults.aspx" id="frmSearch" name="frmSearch">
<table cellspacing="0" cellpadding="0" width="100%" border="0">
<tr bgcolor="#9D0000">
<td background="images/modernliving_bkgrd.gif">
<img align="left" src=http://www.163design.net/n/a/"images/modernliving.gif">
</td>
<td width="94" align="right" bgcolor="#9D0000">
<img src=http://www.163design.net/n/a/"images/search.gif">
</td>
<td width="120" align="right" bgcolor="#9D0000">
<input type="text" name="txtSearch" ID="txtSearch" SIZE="20">
</td>
<td align="left" bgcolor="#9D0000">
<input type="image" src=http://www.163design.net/n/a/"images/arrowbutton.gif" border="0" id="image1" name="image1">
</td>
</tr>
</table>
</form>
</td>
</tr>
</table>
这里没什么可说的，大家都非常熟.
第二个例子（和上一个当然不一样了！）：
Menu.ascx
<%@ Control Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat="server">
//*******************************************************
//
// The Page_Load event on this page is used to obtain
// from a database a list of all product categories
// and databind it to an asp:datalist control.
//
// To optimize performance, this user control is output
// cached (varying based on the categoryId and selection
// passed through the querystring.
//
//*******************************************************
void Page_Load(Object sender, EventArgs e) {
// Set the curent selection of list
String selectionId = Request.Params["selection"];
if (selectionId != null) {
MyList.SelectedIndex = Int32.Parse(selectionId);
}
// Obtain list of menu categories and databind to list control
IBuySpy.ProductsDB products = new IBuySpy.ProductsDB();
MyList.DataSource = products.GetProductCategories();
MyList.DataBind();
}
</script>
<table cellspacing="0" cellpadding="0" width="145" border="0">
<tr valign="top">
<td colspan="2">
<a href="default.aspx"><img src=http://www.163design.net/n/a/"images/logo.gif" border="0"></a>
</td>
</tr>
<tr valign="top">
<td colspan="2">
<asp:DataList id="MyList" runat="server" cellpadding="3" cellspacing="0" width="145" SelectedItemStyle-BackColor="dimgray" EnableViewState="false">
<ItemTemplate>
<asp:HyperLink class="MenuUnselected" id="HyperLink1" Text='<%# DataBinder.Eval(Container.DataItem, "CategoryName") %>' NavigateUrl='<%# "productslist.aspx?CategoryID=" + DataBinder.Eval(Container.DataItem, "CategoryID") + "&selection=" + Container.ItemIndex %>' runat="server" />
</ItemTemplate>
<SelectedItemTemplate>
<asp:HyperLink class="MenuSelected" id="HyperLink2" Text='<%# DataBinder.Eval(Container.DataItem, "CategoryName") %>' NavigateUrl='<%# "productslist.aspx?CategoryID=" + DataBinder.Eval(Container.DataItem, "CategoryID") + "&selection=" + Container.ItemIndex %>' runat="server" />
</SelectedItemTemplate>
</asp:DataList>
</td>
</tr>
<tr>
<td width="10">
</td>
<td>
<br><br><br><br><br><br>
<a href="docs/docs.htm" target="_blank" class="SiteLink">IBuySpy Store<br>Documentation</a>
</td>
</tr>
</table>
三：我们建好了两个.ascx文件，也就我们自己的控件，那怎么用呢？
看下面：
default.aspx
<%@ Page Language="C#" %>
<%@ Register TagPrefix="IBuySpy" TagName="Menu" Src="_Menu.ascx" %>
<%@ Register TagPrefix="IBuySpy" TagName="Header" Src="_Header.ascx" %>
<script runat="server">
//*******************************************************
//
// The Page_Load event on this page is used to personalize
// the welcome message seen by returning IBuySpy users.
// It does this by retrieving a client-side cookie
// (persisted on the client in the Login.aspx and
// register.aspx pages) and updating a label control.
//
//*******************************************************
void Page_Load(Object sender, EventArgs e) {
// Customize welcome message if personalization cookie is present
if (Request.Cookies["IBuySpy_FullName"] != null) {
WelcomeMsg.Text = "Welcome " + Request.Cookies["IBuySpy_FullName"].Value;
}
}
</script>
<html>
<head>
<link rel="stylesheet" type="text/css" href="IBuySpy.css">
</head>
<body background="images/sitebkgrdnogray.gif" leftmargin="0" topmargin="0" rightmargin="0" bottommargin="0" marginheight="0" marginwidth="0">
<table cellspacing="0" cellpadding="0" width="100%" border="0">
<tr>
<td colspan="2">
<IBuySpy:Header ID="Header1" runat="server" />
</td>
</tr>
<tr>
<td valign="top" width=145>
<IBuySpy:Menu id="Menu1" runat="server" />
<img height="1" src=http://www.163design.net/n/a/"images/1x1.gif" width="145">
</td>
<td align="left" valign="top" width="*" nowrap>
<table height="100%" align="left" cellspacing="0" cellpadding="0" width="100%" border="0">
<tr valign="top">
<td nowrap>
<br>
<img align="left" width="24" SRC=http://www.163design.net/n/a/"images/1x1.gif">
<table cellspacing="0" cellpadding="0" width="100%">
<tr>
<td>
<table cellspacing="0" cellpadding="0" width="100%">
<tr>
<td class="HomeHead">
<asp:Label id="WelcomeMsg" runat="server">Welcome to IBuySpy.com</asp:Label>
</td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
</body>
</html>
本鸟是边学边看，不足之处请大虾指点(jiabaoxu@china.com)，谢谢！！
CNet
2000.7.30