将当前时区转换为UTC，递减2小时而不是1小时

Question

我想将一个日期从我的当前时区转换为UTC。

我不能理解这个结果。

代码:

public static String convertToUTC(String dateStr) throws ParseException
{
    Log.i("myDateFunctions", "the input param is:"+dateStr);
    String uTCDateStr;

    Date pickedDate = stringToDate(dateStr, "yyyy-MM-dd HH:mm:ss");
    Log.i("myDateFunctions", "the input param after it is converted to Date:"+pickedDate);

    TimeZone tz = TimeZone.getDefault();
    Date now = new Date();
    Log.i("myDateFunctions:", "my current Timezone:"+tz.getDisplayName()+" +"+(tz.getOffset(now.getTime()) / 3600000));
    // Convert to UTC
    SimpleDateFormat converter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    converter.setTimeZone(TimeZone.getTimeZone("UTC"));
    uTCDateStr = converter.format(pickedDate);
    Log.i("myDateFunctions", "the output, after i converted to UTC timezone:"+uTCDateStr);
    return uTCDateStr;
}

和LogCat结果如下:

03-29 20:31:46.804: I/myDateFunctions(18413): the input param is:2014-04-29 20:00:00
03-29 20:31:47.005: I/myDateFunctions(18413): the input param after it is converted to Date:Tue Apr 29 20:00:00 CEST 2014
03-29 20:31:47.005: I/myDateFunctions:(18413): my current Timezone:Central European Time +1
03-29 20:31:47.005: I/myDateFunctions(18413): the output, after i converted to UTC timezone:2014-04-29 18:00:00

可以看到:我的时区是CET (GMT+1)

那么为什么如果我的输入是20:00，我得到18:00而不是19:00 ?

Answer 1

问题在于夏令时。UTC没有夏令时，如果你的时区有夏令时，它会在一年中部分时间将时差增加1小时。

Answer 2

Game Sechan的答案似乎是正确的。

我只是想展示使用jdbc - time或java时这项工作是多么容易。而不是众所周知的麻烦的java.util.Date和. calendar类。

<标题> Joda-Time h1> Joda-Time 2.4.

String inputRaw = "2014-04-29 20:00:00";
String input = inputRaw.replace( " ", "T" );
DateTimeZone timeZoneIntendedByString = DateTimeZone.forID( "America/Montreal" ); // Or DateTimeZone.getDefault();
DateTime dateTime = new DateTime( input, timeZoneIntendedByString );
DateTime dateTimeUtc = dateTime.withZone( DateTimeZone.UTC ); // Adjust time zones, but still same moment in history of the Universe.