要将所有直接发送到域名www的请求重定向到301，您可以使用:

RewriteEngine On

RewriteCond %{HTTP_HOST} !^([^.]+\.[^.]+){2,}$ [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

这样做的好处是，如果你有任何有效的子域，这将工作。

example.com重定向到www.example.com

没有重定向

没有重定向

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

This starts with the HTTP_HOST variable, which contains just the domain name portion of the incoming URL (example.com). Assuming the domain name does not contain a www. and matches your domain name exactly, then the RewriteRule comes into play. The pattern ^(.*)$ will match everything in the REQUEST_URI, which is the resource requested in the HTTP request (foo/blah/index.html). It stores this in a back reference, which is then used to rewrite the URL with the new domain name (one that starts with www).

[NC]表示不区分大小写的模式匹配，[R=301]表示使用代码301进行外部重定向(资源永久移动)，[L]停止所有进一步重写，并立即重定向。

如果你只想加载www的https版本，在apache虚拟主机文件中使用下面的配置。所有这些都可以放在一个文件中。

重定向所有HTTP到www的HTTPS:

<VirtualHost *:80>
    ServerName example.com
    ServerAlias www.example.com
    Redirect permanent / https://www.example.com/
</VirtualHost>

重定向HTTPS非www到HTTPS www:

<VirtualHost *:443>
    ServerName example.com
    Redirect permanent / https://www.example.com/
</VirtualHost>

实服务器配置

<VirtualHost *:443>
    ServerAdmin hostmaster@example.com
    DocumentRoot "/path/to/your/sites/.htaccess-file-folder"
    SetEnv APPLICATION_ENV "production"

    <Directory "/path/to/your/sites/.htaccess-file-folder">
            Options Indexes FollowSymLinks
            DirectoryIndex index.php index.html
            AllowOverride All
            Order allow,deny
            Allow from all
    </Directory>
    ServerName www.example.com
    
    SSLEngine ON
    SSLCertificateFile "/path/to/your/example.cert.pem"
    SSLCertificateKeyFile "/path/to/your/example.key.pem"

    ErrorLog /path/to/your/example.com-error.log
    CustomLog /path/to/your/example.com-access.log combined
    #Your other configurations if you have
</VirtualHost>

重定向代码的非www => www和相反的www =>非www。在.htaccess文件中没有硬编码域和方案。因此，源域名和http/https版本将被保留。

Apache 2.4及更新版本

www => www:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ %{REQUEST_SCHEME}://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

WWW =>非WWW:

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

注意:在Apache 2.2上无效，%{REQUEST_SCHEME}不可用。为了与Apache 2.2兼容，请使用下面的代码或将%{REQUEST_SCHEME}替换为固定的http/https。

Apache 2.2及更新版本

www => www:

RewriteEngine On

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

．.． 或者更短的版本……

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|offs
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

WWW =>非WWW:

RewriteEngine On

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

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^ https://%1%{REQUEST_URI} [R=301,L]

．.． 更短的版本不可能，因为%N仅可从上次RewriteCond…

重定向域。TLD到www。

以下行可以添加到Apache指令或.htaccess文件中:

RewriteEngine on    
RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http%{ENV:protossl}://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

其他的子域仍在工作。 不需要调整线条。只需复制/粘贴到正确的位置。

如果你修改了vhost，不要忘记应用apache的变化。

(基于默认的Drupal7 .htaccess，但应该在很多情况下工作)

<VirtualHost *:80>
    ServerAlias example.com
    RedirectMatch permanent ^/(.*) http://www.example.com/$1
</VirtualHost>