How to redirect with “www” URL's to without “www” URL's or vice-versa?

问题

I am using ASP.NET 2.0 C#. I want to redirect all request for my web app with "www" to without "www"

www.example.com to example.com

example.com to www.example.com

Stackoverflow.com is already doing this, I know there is a premade mechanism in PHP (.htaccess) file. But how to do it in asp.net ?

Thanks

回答1:

I've gone with the following solution in the past when I've not been able to modify IIS settings.

Either in an HTTPModule (probably cleanest), or global.asax.cs in Application_BeginRequest or in some BasePage type event, such as OnInit I perform a check against the requested url, with a known string I wish to be using:

public class SeoUrls : IHttpModule
{
  #region IHttpModule Members

  public void Init(HttpApplication context)
  {
      context.PreRequestHandlerExecute += OnPreRequestHandlerExecute;
  }

  public void Dispose()
  {
  }

  #endregion

  private void OnPreRequestHandlerExecute(object sender, EventArgs e)
  {
    HttpContext ctx = ((HttpApplication) sender).Context;
    IHttpHandler handler = ctx.Handler;

    // Only worry about redirecting pages at this point
    // static files might be coming from a different domain
    if (handler is Page)
    {
      if (Ctx.Request.Url.Host != WebConfigurationManager.AppSettings["FullHost"])
      {
        UriBuilder uri = new UriBuilder(ctx.Request.Url);

        uri.Host = WebConfigurationManager.AppSettings["FullHost"];

        // Perform a permanent redirect - I've generally implemented this as an 
        // extension method so I can use Response.PermanentRedirect(uri)
        // but expanded here for obviousness:
        response.AddHeader("Location", uri);
        response.StatusCode = 301;
        response.StatusDescription = "Moved Permanently";
        response.End();
      }
    }
  }
}

Then register the class in your web.config:

<httpModules>
  [...]
  <add type="[Namespace.]SeoUrls, [AssemblyName], [Version=x.x.x.x, Culture=neutral, PublicKeyToken=933d439bb833333a]" name="SeoUrls"/>
</httpModules>

This method works quite well for us.

回答2:

There's a Stackoverflow blog post about this.

http://blog.stackoverflow.com/2008/06/dropping-the-www-prefix/

Quoting Jeff:

Here’s the IIS7 rule to remove the WWW prefix from all incoming URLs. Cut and paste this XML fragment into your web.config file under

<system.webServer> / <rewrite> / <rules>

<rule name="Remove WWW prefix" >
<match url="(.*)" ignoreCase="true" />
<conditions>
<add input="{HTTP_HOST}" pattern="^www\.domain\.com" />
</conditions>
<action type="Redirect" url="http://domain.com/{R:1}"
    redirectType="Permanent" />
</rule>

Or, if you prefer to use the www prefix, you can do that too:

<rule name="Add WWW prefix" >
<match url="(.*)" ignoreCase="true" />
<conditions>
<add input="{HTTP_HOST}" pattern="^domain\.com" />
</conditions>
<action type="Redirect" url="http://www.domain.com/{R:1}"
    redirectType="Permanent" />
</rule>

回答3:

The accepted answer works for a single URL or just a few, but my application serves hundreds of domain names (there are far too many URLs to manually enter).

Here is my IIS7 URL Rewrite Module rule (the action type here is actually a 301 redirect, not a "rewrite"). Works great:

<rule name="Add WWW prefix" >
  <match url="(.*)" ignoreCase="true" />
  <conditions>
   <add input="{HTTP_HOST}" negate="true" pattern="^www\.(.+)$" />
  </conditions>
  <action type="Redirect" url="http://www.{HTTP_HOST}/{R:1}" 
       appendQueryString="true" redirectType="Permanent" />
</rule>

回答4:

In order to answer this question, we must first recall the definition of WWW:

World Wide Web: n. Abbr. WWW

The complete set of documents residing on all Internet servers that use the HTTP protocol, accessible to users via a simple point-and-click system.
n : a collection of internet sites that offer text and graphics and sound and animation resources through the hypertext transfer protocol. By default, all popular Web browsers assume the HTTP protocol. In doing so, the software prepends the 'http://' onto the requested URL and automatically connect to the HTTP server on port 80. Why then do many servers require their websites to communicate through the www subdomain? Mail servers do not require you to send emails to recipient@mail.domain.com. Likewise, web servers should allow access to their pages though the main domain unless a particular subdomain is required.

Succinctly, use of the www subdomain is redundant and time consuming to communicate. The internet, media, and society are all better off without it.

Using the links at the top of the page, you may view recently validated domains as well as submit domains for real-time validation.

Apache Webserver:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

Windows Server/IIS: ~~There is no way.~~

You can use Url Rewriter from Code Plex. With the same syntax.

RewriteCond %{HTTP_HOST} !^(www).*$ [NC]
RewriteRule ^(.*)$ http://www.%1$1 [R=301]

Source

回答5:

This is usually handled by your web server directly in the configuration. As you mentioned, the .htaccess file does this for the Apache web server -- it has nothing to do with PHP. Since you're using ASP, it's a near certainty your server is IIS. I know there is a way to set up this direct with IIS, but I don't know what it is. You may be aided in your search by knowing you should be googling for things related to "IIS redirect", not "ASP redirect".

That said, you CAN do it in PHP, and almost certainly ASP as well, but you'll have to have hitting any URL at the wrong domain invoke an ASP script that performs the redirect operation (using appropriate API calls or by setting headers directly). This will necessitate some URL rewriting or somesuch on the part of the server so that all URLs on the wrong host are handled by your script... just do it directly at the server in the first place :)

回答6:

We did this on IIS 6 quite simply. We essentially created a second virtual server that had nothing on it than a custom 404 page .aspx page. This page caught any requests for WHATEVERSERVER.com/whateverpage.aspx and redirected to the real server by changing the URL to be www.whateverserver.com/whateverpage.aspx.

Pretty simple to setup, and has the advantage that it will work with any domains that come in to it (if you have multiple domains for instance) without having to setup additional rules for each one. So any requests for www.myoldserver.com/xxx will also get redirected to www.whateverserver.com/xxx

In IIS 7, all this can be done with the URL writing component, but we prefer to keep the redirects off on this virtual server.

回答7:

In case you are using IIS 7, simply navigate to URL rewrite and add the canonical domain name rule.

P.S. Its to make sure that you get redirected from domain.com to www.domain.com

回答8:

This version will:

Maintain the http/https of the incoming request.
Support various hosts in case you need that (e.g. a multi-tenant app that differentiates tenant by domain).

<rule name="Redirect to www" stopProcessing="true">
  <match url="(.*)" />
  <conditions trackAllCaptures="true">
    <add input="{CACHE_URL}" pattern="^(.+)://" />
    <add input="{HTTP_HOST}" negate="true" pattern="^www\.(.+)$" />
  </conditions>
  <action type="Redirect" url="{C:1}://www.{HTTP_HOST}/{R:1}" />
</rule>

来源：https://stackoverflow.com/questions/521804/how-to-redirect-with-www-urls-to-without-www-urls-or-vice-versa

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