Nginx开启强制HTTPS：
if ($server_port !~ 443){
rewrite ^(/.*)$ https://$host$1 permanent;
}
Nginx开启强制HTTPS访问并保留指定目录的HTTP访问：（排除wp-admin目录）
#HTTP_TO_HTTPS_START
if ($server_port !~ 443){
rewrite ^/((?!wp-admin).*)$ https://$host$1 permanent;
}
#HTTP_TO_HTTPS_END
