Equivalent to master pages in ASP Classic_问答_开发者

Is it possible to build some kind of master page with Classic ASP without frames or开发者_Go百科 iframes?

I’m wondering if there is a way to include content pages in the main page like ASP.NET master pages do. From what I have researched, ASP Classic does support inclusion of other ASP/HTML pages into a page, but the value put into this include means the function cannot be dynamic.

You could just create functions (say, a Header() function and a Footer() function) which do nothing but output some set of markup. Those functions can take parameters too, and be called conditionally. It's not quite the same as a Master page, but it sounds like it accomplishes what you are trying to do. You would have an  on each page, and each page would call Header() & Footer().

Or you can just use  at the top and  at the bottom of each page too. I've seen both approaches.

If you are looking for the reverse, that is, a single template page which calls individual pages in it's "middle" section, then that's not really something you can do easily with ASP classic. It's a fundamental difference in approach: ASP.NET has a concept of a control tree, events, etc, while ASP Classic is essentially just a script that runs top to bottom.

This idea is from Classic ASP Master Pages | Godless Code. I’ve transcribed the code in images on that page, extended its example a bit, and also explored the limitations of this technique.

The idea is that each page has only one Server-Side Include (one  call). The single inclusion is a master template file, which you could name master.asp. The master page calls custom subroutines on each page in place of each content area. Each child page defines those subroutines with Sub, with content unique to that child page.

master.asp

<!DOCTYPE html>
<html>
    <head>
        <title><% Title() %></title>
    </head>
    <body>
        <% BodyContent() %>
    </body>
</html>

aboutUs.asp

<!--#include file="master.asp" -->

<% Sub Title %> About Us <% End Sub %>

<% Sub BodyContent %>
    <h1>About Us</h1>
    <p>
        We do things!
    </p>
<% End Sub %>

That turns into this HTML when you visit aboutUs.asp on an IIS server:

<!DOCTYPE html>
<html>
    <head>
        <title> About Us </title>
    </head>
    <body>

    <h1>About Us</h1>
    <p>
        We do things!
    </p>

    </body>
</html>

However, this approach does not allow nesting:

subtemplate.asp

<div class="innerLogo <% LogoSide() %>">
    <% LogoImg() %>
</div>

template_user.asp

<!--#include file="master.asp" -->

<% Sub Title %> Our Logo <% End Sub %>

<% Sub BodyContent %>

    <!--#include file="subtemplate.asp" -->

    <% Sub LogoSide %> leftside <% End Sub %>

    <% Sub LogoImg %>
        <img src="img/about.png" alt="About" />
    <% End Sub %>

<% End Sub %>

This will not work, because nested Subs are a syntax error:

Microsoft VBScript compilation error '800a03ea'

Syntax error

/template_user.asp, line 9
Sub LogoSide
^

Since nesting is not allowed, this templating system is, in effect, a one-time solution. If your individual pages’ subroutines become too unwieldy, you can’t use this technique again. So when using this technique, you should carefully choose where to carve out your set of templates in order to provide the best balance between flexibility and DRYness.

Rory wrote a great example for master pages in Classic ASP, but demonstrated that the "master page" approach had its limitations because Subs cannot be nested.

However, for the sake of demonstration, and because JavaScript in Classic ASP has hardly any documentation anywhere on the Internet, here's the same example that fails in ASP VBScript but won't fail in ASP JavaScript.

master.asp

<!DOCTYPE html>
<html>
    <head>
        <title><% Title() %></title>
    </head>
    <body>
        <% BodyContent() %>
    </body>
</html>

subtemplate.asp

<div class="innerLogo <% LogoSide() %>">
    <% LogoImg() %>
</div>

template_user.asp

<%@ Language= "Javascript" %> 
<!--#include file="master.asp" -->

<% function Title() { %> About Us <% } %>

<% function BodyContent() { %>

    <!--#include file="subtemplate.asp" -->

    <% function LogoSide() { %> leftside <% } %>

    <% function LogoImg() { %>
        <img src="img/about.png" alt="About" />
    <% } %>
<% } %>

It works! here are the juicy results:

<!DOCTYPE html>
<html>
    <head>
        <title> About Us </title>
    </head>
    <body>

    <div class="innerLogo  leftside ">
      <img src="img/about.png" alt="About" />
    </div>

    </body>
</html>

Remember, JavaScript, even the ECMAScript 3 version in Classic ASP, is often way more powerful and expressive than the VBScript engine that was favoured and heavily promoted by Microsoft. If you ever have to use Classic ASP, use JavaScript!

One of the ugliest problems in classic ASP is that #includes always happen, so putting two includes in an if-then-else construct always includes both – even though you only see the output that applies to your conditional value.

Even when includes work, they don't give you the result you're really looking for, which is to select a template or skin “on the fly”.

One way to handle this situation is to use a template engine such as KudzuASP that surpasses the traditional #include methodology. Here is a very simple example:

<!-- An HTML Template -->
<html>
<head><title><!--[Replace|PageTitle]-->PageTitle<!--[/Replace]--></title></head>
<body>
<table border="1" cellpadding="4" callspacing="2" width="640">
<tr>
    <td colspan="2"><!--[HeaderContent/]--></td>
</tr>
<tr>
    <td width="160"><!--[LeftColumnContent/]--></td>
    <td><!--[MainContent/]--></td>
</tr>
<tr>
    <td colspan="2"><!--[FooterContent/]--></td>
</tr>
</table>
</body>
</html>

And the ASP code looks like this:

<%@ Language=VBScript %>
<!-- #include file="./KudzuASP/_kudzu.asp" -->
<%
Dim PageTitle : PageTitle = "This is a Master Page"

'
' Create the template engine
'
Dim T_ENGINE
Set T_ENGINE = New CTemplateEngine

T_ENGINE.PutValue "PageTemplate", PageTemplate
T_ENGINE.SetHandler "HeaderContent", New CTXHeaderContent
T_ENGINE.SetHandler "LeftColumnContent", New CTXLeftColumnContent
T_ENGINE.SetHandler "MainContent", New CTXMainContent
T_ENGINE.SetHandler "FooterContent", New CTXFooterContent

'
' Custom Tage Handlers
'
Class CTXHeaderContent
    Public Sub HandleTag(vNode)
        vNode.Engine.ContentAppend "Header"
    End Sub
End Class

Class CTXLeftColumnContent
    Public Sub HandleTag(vNode)
        vNode.Engine.ContentAppend "Left<br/>Content"
    End Sub
End Class

Class CTXMainContent
    Public Sub HandleTag(vNode)
        vNode.Engine.ContentAppend "Main<br/>Content"
    End Sub
End Class

Class CTXFooterContent
    Public Sub HandleTag(vNode)
        vNode.Engine.ContentAppend "Footer"
    End Sub
End Class

'
' Evaluate the template
'
T_ENGINE.ParseFile Server.MapPath("./MasterPage.html")
T_ENGINE.EvalTemplate
%>

The template engine makes calls to your custom objects defined in the hosting ASP code page when the appropriate tags are processed. The function members of your custom classes have direct access to the hosting page and its variables and methods, as well as the template engine’s object hierarchy. In other words, the template is driving the output and the hosting ASP page during output.

This beats the include mechanism hands down, because the template engine can dynamically select which HTML template to process at runtime, and it can dynamically include libraries of custom tag handlers using the built in  tag.

UPDATE 2016.01.13: I have open sourced this project and you can find the latest code maintained at this address: https://github.com/Mumpitz/KudzuASP

I just use a Default.asp page with html, then put my code in the content area.

<%@ Language="VBScript" %>
    <!DOCTYPE html>
    <html lang="en">
        <head>
             <meta charset="utf-8" />
        </head>
        <body>
            <div id="topNav"> <!--begin top Nav-->
                <ul> 
                    <!--Be sure that all links are like this href="?page=contentPageEx"-->
                    <li><a href="?page=home">Home</a></li> 
                </ul>   
            </div> <!--end top Nav-->

            <div id="content">
                   <%
                        Dim default
                        default= Request.QueryString 
                        If default= "" Then 
                        Server.execute "includes/home.html"
                        Else 
                        Server.execute "includes/" & request("page")  & ".html"
                        end if 
                    %>   
            </div>  


            <div id="botNav"> <!--begin bot Nav-->
                <ul> 
                  <li><a href="?page=home">Home</a></li>   
                </ul>
            </div> <!--end Bot Nav-->

         </body>
</html>

Then I put all my content into an includes file with html pages.

  <!DOCTYPE html>

    <html lang="en">
        <head>
            <meta charset="utf-8" />

            <!--Search engines use this title ect...-->
            <title>Hello SEO! This is a content page!</title>
            <!--Can be styled independently-->
            <style>
              p {
                    color: #0094ff;   
                }  
            </style>
        </head>
        <body>
         <p>Hello World!</p>   
        </body>
    </html>