我所见过的最流行的(==标准?)确定时区的方法是简单地询问用户自己。如果你的网站需要订阅，这可以保存在用户的个人资料数据。对于anon用户，日期可以显示为UTC或GMT或类似的格式。

我可不想自作聪明。只是有时候有些问题在任何编程环境之外都有更好的解决方案。

使用PHP日期函数，您将获得网站所在服务器的日期时间。获取用户时间的唯一方法是使用JavaScript。

但是我建议你，如果你的网站有注册要求，那么最好的方法是要求用户注册作为一个强制性的字段。您可以在注册页面中列出各种时区，并将其保存在数据库中。在此之后，如果用户登录到站点，那么您可以根据用户选择的时区为该会话设置默认时区。

可以使用PHP函数date_default_timezone_set设置任何特定的时区。为用户设置指定的时区。

基本上，用户的时区会传到客户端，所以我们必须使用JavaScript。

下面是使用PHP和JavaScript获取用户时区的脚本。

<?php
    #http://www.php.net/manual/en/timezones.php List of Time Zones
    function showclienttime()
    {
        if(!isset($_COOKIE['GMT_bias']))
        {
?>

            <script type="text/javascript">
                var Cookies = {};
                Cookies.create = function (name, value, days) {
                    if (days) {
                        var date = new Date();
                        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
                        var expires = "; expires=" + date.toGMTString();
                    }
                    else {
                        var expires = "";
                    }
                    document.cookie = name + "=" + value + expires + "; path=/";
                    this[name] = value;
                }

                var now = new Date();
                Cookies.create("GMT_bias",now.getTimezoneOffset(),1);
                window.location = "<?php echo $_SERVER['PHP_SELF'];?>";
            </script>

            <?php

        }
        else {
          $fct_clientbias = $_COOKIE['GMT_bias'];
        }

        $fct_servertimedata = gettimeofday();
        $fct_servertime = $fct_servertimedata['sec'];
        $fct_serverbias = $fct_servertimedata['minuteswest'];
        $fct_totalbias = $fct_serverbias – $fct_clientbias;
        $fct_totalbias = $fct_totalbias * 60;
        $fct_clienttimestamp = $fct_servertime + $fct_totalbias;
        $fct_time = time();
        $fct_year = strftime("%Y", $fct_clienttimestamp);
        $fct_month = strftime("%B", $fct_clienttimestamp);
        $fct_day = strftime("%d", $fct_clienttimestamp);
        $fct_hour = strftime("%I", $fct_clienttimestamp);
        $fct_minute = strftime("%M", $fct_clienttimestamp);
        $fct_second = strftime("%S", $fct_clienttimestamp);
        $fct_am_pm = strftime("%p", $fct_clienttimestamp);
        echo $fct_day.", ".$fct_month." ".$fct_year." ( ".$fct_hour.":".$fct_minute.":".$fct_second." ".$fct_am_pm." )";
    }

    showclienttime();
?>

但在我看来，最好是询问用户在你的项目中是否必须注册。

下面是一篇文章(带源代码)，解释如何在ASP中确定和使用本地化时间。净(VB。NET, c#)应用程序:

是时候了

In short, the described approach relies on the JavaScript getTimezoneOffset function, which returns the value that is saved in the session cookie and used by code-behind to adjust time values between GMT and local time. The nice thing is that the user does not need to specify the time zone (the code does it automatically). There is more involved (this is why I link to the article), but provided code makes it really easy to use. I suspect that you can convert the logic to PHP and other languages (as long as you understand ASP.NET).

我是这样做的。这将把PHP默认时区设置为用户的本地时区。只需将以下内容粘贴到所有页面的顶部:

<?php
session_start();

if(!isset($_SESSION['timezone']))
{
    if(!isset($_REQUEST['offset']))
    {
    ?>
        <script>
        var d = new Date()
        var offset= -d.getTimezoneOffset()/60;
        location.href = "<?php echo $_SERVER['PHP_SELF']; ?>?offset="+offset;
        </script>
        <?php   
    }
    else
    {
        $zonelist = array('Kwajalein' => -12.00, 'Pacific/Midway' => -11.00, 'Pacific/Honolulu' => -10.00, 'America/Anchorage' => -9.00, 'America/Los_Angeles' => -8.00, 'America/Denver' => -7.00, 'America/Tegucigalpa' => -6.00, 'America/New_York' => -5.00, 'America/Caracas' => -4.30, 'America/Halifax' => -4.00, 'America/St_Johns' => -3.30, 'America/Argentina/Buenos_Aires' => -3.00, 'America/Sao_Paulo' => -3.00, 'Atlantic/South_Georgia' => -2.00, 'Atlantic/Azores' => -1.00, 'Europe/Dublin' => 0, 'Europe/Belgrade' => 1.00, 'Europe/Minsk' => 2.00, 'Asia/Kuwait' => 3.00, 'Asia/Tehran' => 3.30, 'Asia/Muscat' => 4.00, 'Asia/Yekaterinburg' => 5.00, 'Asia/Kolkata' => 5.30, 'Asia/Katmandu' => 5.45, 'Asia/Dhaka' => 6.00, 'Asia/Rangoon' => 6.30, 'Asia/Krasnoyarsk' => 7.00, 'Asia/Brunei' => 8.00, 'Asia/Seoul' => 9.00, 'Australia/Darwin' => 9.30, 'Australia/Canberra' => 10.00, 'Asia/Magadan' => 11.00, 'Pacific/Fiji' => 12.00, 'Pacific/Tongatapu' => 13.00);
        $index = array_keys($zonelist, $_REQUEST['offset']);
        $_SESSION['timezone'] = $index[0];
    }
}

date_default_timezone_set($_SESSION['timezone']);

//rest of your code goes here
?>

简单，只需使用JavaScript的getTimezoneOffset函数，如下所示:

-new Date().getTimezoneOffset()/60;

不要使用IP地址来明确地确定位置(以及时区)——这是因为使用NAT、代理(越来越流行)和vpn, IP地址不一定真实地反映用户的实际位置，而是反映实现这些协议的服务器所在的位置。

类似于美国的区号对于定位电话用户不再有用，因为号码可携性很流行。

IP地址和上面显示的其他技术对于建议用户可以调整/纠正的默认值很有用。