php 判断访问来源是否是https

// 访问来源是否是https
//方法一：
if($_SERVER["HTTPS"] <> "on"){
    $url="https://".$_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
    header("Location: ".$url);
} 
//方法二：
function is_https(){
    if ( ! empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off')
    {
        return TRUE;
    }
    elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https')
    {
        return TRUE;
    }
    elseif ( ! empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off')
    {
        return TRUE;
    }
    return FALSE;
};