我的htaccess是这么写的RewriteEngine on
#RewriteRule !\.(js|ico|gif|jpg|png|css)$ index.php
RewriteCond %{HTTP_HOST} ^[a-z0-9\-]+\.xxx\.com$
#RewriteCond %{HTTP_HOST} ^(www.)?(?!/.|www|bbs)(.*)\.xxx\.com$
RewriteRule ^/?$ /%{HTTP_HOST}
RewriteRule www\.xxx\.com/?$ /main/index.php [L]
RewriteRule gallery\.xxx\.com/?$ /gallery/index.php [L] 
RewriteRule bbs\.xxx\.com/?$ /bbs/index.php [L] 
RewriteRule ^/([a-z0-9\-]+)\.xxx\.com/?$ /user/index.php?username=$1 [L] 请问如何才能在上面已经写的规则的基础上将www.xxx.com/login.html rewrite到/main/login.php?