此重定向代码可以直接添加到vhost文件中，也可以添加到.htaccess文件中：

RewriteEngine on

# rewrite to https.
# -----------------
# %{HTTP:X-Forwarded-Proto} !https: This condition checks if the X-Forwarded-Proto header is not set to https. 
# The X-Forwarded-Proto #header is typically set by proxies or load balancers to indicate the original protocol 
# used for the request. By checking this header, # you can ensure that the redirect only occurs if the request 
# is not already using HTTPS.
RewriteCond %{HTTP:X-Forwarded-Proto} !https

# %{HTTP:Upgrade-Insecure-Requests} ^1$: This condition checks if the Upgrade-Insecure-Requests header is set to 1. 
# The Upgrade-Insecure-Requests header is sent by modern browsers that support HTTPS and can automatically upgrade 
# an insecure request to a secure one. By checking this header, you can verify if the browser supports HTTPS and 
# wants to upgrade the request to HTTPS.
RewriteCond %{HTTP:Upgrade-Insecure-Requests} ^1$

# RewriteRule ^/?(.*) https://%{SERVER_NAME}/$1 [R,L]
RewriteRule ^/?(.*) https://%{SERVER_NAME}/$1 [R=301,L]

在内部，它检查Upgrade-Insecure-Requests头，这是浏览器发送的内容。基于此请求标头，它重定向页面。