关于.net的自定义控件（请各位大虾指正）

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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="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="images/sign_in.gif" border="0">
                                        Sign In</a>
                                </td>
                                <td align="center" width="75">
                                    <a href="OrderList.aspx" class="SiteLinkBold"><img src="images/account.gif" border="0">
                                        Account</a>
                                </td>
                                <td align="center" width="55">
                                    <a href="ShoppingCart.aspx" class="SiteLinkBold"><img src="images/cart.gif" border="0">
                                        Cart</a>
                                </td>
                                <td align="center" width="65">
                                    <a href="InstantOrder.asmx" class="SiteLinkBold"><img src="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="images/modernliving.gif">
                        </td>
                        <td width="94" align="right" bgcolor="#9D0000">
                            <img src="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="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="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="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>
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