如何将域重定向到安全SSL？

I have a domain and want it to redirect to secure ssl with https. how can I do it? because sometimes it goes to http domain, not https domain.

For Apache you can use this code lines in .htaccess file;

RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R,L]