地址栏中显示 www 的问题

Question

我最近购买了一个 VPS 和一个域名。VPS 运行的是 Ubuntu 16.04 和 Apache 2.4。当我在浏览器中输入 时http://example.com，索引页可以正确加载。如果我www在域名前输入 ，也会发生同样的事情，但在这种情况下www会消失。

如何让它www停留在地址栏中并重定向所有non-www请求？这对我来说至关重要，因为我已经为www包含以下内容的域购买了 SSL 证书。

我尝试修改 DNS 设置以实现这一点，但到目前为止，我的所有尝试都失败了。

我当前（工作）的设置是：

=== A records ===
[empty]     31.14.131.29
localhost   127.0.0.1
webmail     62.149.158.92
webmail     62.149.158.91
www         31.14.131.29

=== AAAA records ===
None

=== CNAME records ===
None

我也尝试过使用.htaccess，但显然请求陷入了循环。

这是我第一次设置 VPS，感觉有点迷茫。你能告诉我正确的设置方法吗？

编辑：000-default.conf文件内容

<VirtualHost *:80>
    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.
    ServerName www.grandegiove.com

    ServerAdmin [email protected]
    DocumentRoot /var/www/html

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf
</VirtualHost>

编辑：.htaccess内容文件

Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^grandegiove.com[nc]
RewriteRule ^(.*)$ http://www.grandegiove.com/$1 [l,r=301,nc]

但 www 仍然没有显示。