我建议用301重定向:

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

最佳解决方案取决于您的需求。这是对之前发布的答案的总结，并添加了一些上下文。

如果你使用Apache web服务器并且可以更改其配置，请参考Apache文档:

<VirtualHost *:80>
    ServerName www.example.com
    Redirect "/" "https://www.example.com/"
</VirtualHost>

<VirtualHost *:443>
    ServerName www.example.com
    # ... SSL configuration goes here
</VirtualHost>

但你还问是否可以在.htaccess文件中进行。在这种情况下，你可以使用Apache的RewriteEngine:

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

如果一切正常，你想让浏览器记住这个重定向，你可以将最后一行更改为:

RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

但如果你在这个方向上改变了主意，要小心。浏览器会记住它很长一段时间，不会检查它是否改变了。

根据web服务器配置，您可能不需要第一行RewriteEngine On。

如果你在寻找一个PHP解决方案，看看$_SERVER数组和header函数:

if (!$_SERVER['HTTPS']) {
    header("Location: https://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']); 
} 

Not only can you do this in your .htaccess file, you should be doing this period. You will also want to follow the steps here to get your site listed on the HSTS preload list after you implement this redirect so that any requests to the insecure http version of your website never make it past the user agent. Instead, the user agent checks the requested URI against a baked in list of https only websites and, if the requested URI is on that list, changes the protocol from http to https before transmitting the request to the server. Therefore, the insecure request never makes it out into the wild and never hits the server. Eventually when the internet changes over to https only the HSTS preload list will not be needed. Until then, every site should be using it.

为了执行重定向，我们需要启用重写引擎，然后将所有流量从http端口80重定向到https。

RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://yourwebsite.tld/$1 [L,R=301]

在.htaccess文件中使用以下代码自动将访问者重定向到站点的HTTPS版本:

RewriteEngine On

RewriteCond %{HTTPS} off

RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

如果你有一个现有的。htaccess文件:

不要重复“重写引擎”。

确保以RewriteCond和RewriteRule开头的行立即跟随已经存在的RewriteEngine On。

这是html重定向方法，它的工作，但不是最好的。

 <meta http-equiv="Refresh" content="0;URL=https://www.example.com" />

PHP方法

<?php
function redirectTohttps() {
    if ($_SERVER['HTTPS']!="on") {
        $redirect= "https://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
        header("Location:$redirect"); 
    } 
}
?>

.htaccess approch

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

抄袭: www.letuslook.org

更新:尽管这个答案在几年前就已经被接受了，但请注意，Apache文档现在不建议使用这种方法。改用重定向。请看这个答案。

RewriteEngine On
RewriteCond %{HTTPS} !on
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}