将 UTC 时间转换为 Java 中的本地时区

问题描述

我知道这个主题已经被打死了，但是在搜索了几个小时之后我不得不问这个问题.

I know this subject has been beaten to death but after searching for a few hours to this problem I had to ask.

我的问题:根据客户端应用程序 (iphone) 的当前时区计算服务器上的日期.客户端应用程序以秒为单位告诉服务器其时区距 GMT 有多远.然后我想使用这些信息来计算服务器中的日期.服务器上的日期都存储为 UTC 时间.所以我想在转换为本地时区后获取 UTC Date 对象的 HOUR.

My Problem: do calculations on dates on a server based on the current time zone of a client app (iphone). The client app tells the server, in seconds, how far away its time zone is away from GMT. I would like to then use this information to do computation on dates in the server. The dates on the server are all stored as UTC time. So I would like to get the HOUR of a UTC Date object after it has been converted to this local time zone.

我目前的尝试:

int hours = (int) Math.floor(secondsFromGMT / (60.0 * 60.0));
int mins = (int) Math.floor((secondsFromGMT - (hours * 60.0 * 60.0)) / 60.0);
String sign = hours > 0 ? "+" : "-";

Calendar now = Calendar.getInstance();
TimeZone t = TimeZone.getTimeZone("GMT" + sign + hours + ":" + mins);
now.setTimeZone(t);

now.setTime(someDateTimeObject);

int hourOfDay = now.get(Calendar.HOUR_OF_DAY);

变量 hour 和 mins 表示本地时区与 GMT 相差的小时和分钟.调试此代码后 - 变量小时、分钟和符号是正确的.

The variables hour and mins represent the hour and mins the local time zone is away from GMT. After debugging this code - the variables hour, mins and sign are correct.

问题是 hourOfDay 没有返回正确的小时 - 它返回的是 UTC 时间的小时，而不是本地时间.想法?

The problem is hourOfDay does not return the correct hour - it is returning the hour as of UTC time and not local time. Ideas?

推荐答案

您的时区字符串格式不正确.试试这个，

You timezone string is formulated incorrectly. Try this,

String sign = secondsFromGMT > 0 ? "+" : "-";
secondsFromGMT = Math.abs(secondsFromGMT);      
int hours = secondsFromGMT/3600;
int mins = (secondsFromGMT%3600)/60;
String zone = String.format("GMT%s%02d:%02d", sign, hours, mins);          
TimeZone t = TimeZone.getTimeZone(zone);

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