加载login.aspx时,table居上。如图登录提示错误后,table居中,如图想让页面加载时就如图2,居中,怎么做?(30分)
代码:<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="login.aspx.cs" Inherits="WebApp_DataManage.login" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
   <title>
            <%=page_title%>
</title>
<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" Content="C#">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style type="text/css">
 BODY { MARGIN: 0px; BACKGROUND-COLOR: #66b3ff}
 .style3 { FONT-SIZE: 12px; COLOR: #666666 }
 .style4 { FONT-SIZE: 12px; COLOR: #ffffff }
a:link {
color: #FFFFFF;
text-decoration: none;
}
a:visited {
color: #FFFFFF;
text-decoration: none;
}
a:hover {
color: #FF0000;
text-decoration: underline;
}
a:active {
color: #FFFFFF;
text-decoration: none;
}
body,td,th {
font-size: 12px;
}
a {
font-size: 12px;
}
</style>
</head>
<body MS_POSITIONING="GridLayout" oncontextmenu="return false;" onselectstart="return false;"
ondragstart="return false;" scroll="no">
   <table width="100%" height="100%" border="0" align="center">
<td>
<form id="Form1" method= "post" runat="server">
<div align="center">
<table border="0">                                <td  width="650" height="400" background="images/login/login.jpg">
                                    <table width="100%" border="0">
<tr>
<td width="55%" rowspan="4">
<div style="DISPLAY:none">

</div>
    <asp:ValidationSummary ID="ValidationSummary1" runat="server" Font-Size="12px" 
                                                        ShowMessageBox="True" />
</td>
<td width="38%" height="70" colspan="2">&nbsp;</td>
<td width="7%">&nbsp;</td>
</tr>
<tr>
<td colspan="2">
                                                <table width="267" border="0">
<tr>
<td width="20"><div align="right">
                                                                <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" 
                                                                    ControlToValidate="UserID" ErrorMessage="用户名2-15字以内!" Font-Size="12px" 
                                                                    ValidationExpression="^[*\W\w\s\S]{2,15}">*</asp:RegularExpressionValidator>
                                                                <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
                                                                    ControlToValidate="UserID" ErrorMessage="请输入用户名!" Font-Size="12px">*</asp:RequiredFieldValidator>
                                                                <img src="images/login/arrow.gif" width="4" height="7"></div>
</td>
<td><span class="style3">用户名</span></td>
<td colspan="2">
<asp:TextBox id="UserID" runat="server" Width="100px" CssClass="textbox_1" Height="18px" BorderColor="#000000"
BorderWidth="1px" MaxLength="15" tabIndex="1"></asp:TextBox>
</td>
<td rowspan="3">
                                                                <asp:ImageButton ID="ImageButton_login" runat="server" 
                                                                    ImageUrl="images/login/button.gif" onclick="ImageButton_login_Click" 
                                                                    TabIndex="4"/>
                                                            </td>
</tr>
<tr>
<td width="20"><div align="right">
                                                                <asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" 
                                                                    ControlToValidate="UserPSW" ErrorMessage="密码6-15字以内!" Font-Size="12px" 
                                                                    ValidationExpression="^[*\W\w\s\S]{6,15}">*</asp:RegularExpressionValidator>
                                                                <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" 
                                                                    ControlToValidate="UserPSW" ErrorMessage="请输入密码!" Font-Size="12px">*</asp:RequiredFieldValidator>
                                                                <img src="images/login/arrow.gif" width="4" height="7"></div>
</td>
<td><span class="style3">密 码</span></td>
<td colspan="2">
<asp:TextBox id="UserPSW" runat="server" Width="100px" Height="18px" BorderColor="#000000" BorderWidth="1px"
CssClass="textbox_1" TextMode="Password" Font-Size="12px" MaxLength="15" tabIndex="2"></asp:TextBox>
</td>
</tr>
<tr>
<td width="20"><div align="right">
                                                                <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" 
                                                                    ControlToValidate="ValidateCode" ErrorMessage="请输入验证码!" Font-Size="12px">*</asp:RequiredFieldValidator>
                                                                <img src="images/login/arrow.gif" width="4" height="7"></div>
</td>
<td><span class="style3">验证码</span></td>
<td width="48">
<asp:TextBox id="ValidateCode" runat="server" Width="48px" CssClass="textbox_1" Height="18px"
MaxLength="4" BorderColor="#000000" BorderWidth="1px" tabIndex="3"></asp:TextBox>
</td>
<td width="40">
<asp:Image id="ImageCheck" runat="server" ImageUrl="share/ValidateCode.aspx" Width="40px"></asp:Image>
</td>
</tr>
</table>
</td>
<td>&nbsp;</td>
</tr>
<tr>
                                                
<td><div align="center"><span class="style4"><a href="?"><font color="#ffffff" tabIndex="5">看不清验证码?</font></a></span></div></td>
<td><div align="center"><a href="help/JumpPage/JumpPage.htm"  target="_blank">无法登陆系统?</a></div></td>
<td>&nbsp;</td>
</tr>
<tr>
<td colspan="2">&nbsp;</td>
<td>&nbsp;</td>
</tr>
</table>
</td>
</tr>
</table>
</div>
</form>
<div align="center" style="FONT-SIZE: 12px"><asp:Label id="label_Version" 
                            runat="server" ForeColor="White"></asp:Label></div>
</td>
</tr>
</table>
        <SCRIPT language="javascript">
            if (self != top)
            { top.location = self.location; }
</SCRIPT>
</body>
</html>

解决方案 »

  1.   

    <table   width= "100% "   border= "0 "   cellspacing= "0 "   cellpadding= "0 "   height= "100% ">     //“顶天立地”的框架   height= "100 "很重要 
        <tr>   
            <td> &nbsp; </td> 
        </tr> 
        <tr>   
            <td   align= "center ">     //中间一层,里面是你自己的表格 
                <table   border= "1 "   cellspacing= "0 "   cellpadding= "0 "> 
                    <tr> 
                        <td> &nbsp; </td> 
                    </tr> 
                </table> 
            </td> 
        </tr> 
        <tr> 
            <td> &nbsp; </td> 
        </tr> 
    </table>