转换日期时间到时区，设置时间和转换回

Question

我有，其中转换的DateTime到特定DateTimeZone一个小工具的方法，设置在该时区的时间，并再次转换到另一个时区：

/** 
* Delivers a DateTime with changed time in the specified DateTimeZone. 
* 
* @param dateTime  the date time to convert 
* @param hour   the hour to set in the client timezone date time 
* @param minute  the minute to set in the client timezone date time 
* @param second  the second to set in the client timezone date time 
* @param dtzConversion the client time zone 
* @param dtzReturn  the time zone of the return date time (optionally: can be null) 
* @return the date time 
*/ 
public DateTime convertDateTimeToTimeZone(final DateTime dateTime, final int hour, final int minute, final int second, 
              final DateTimeZone dtzConversion, final DateTimeZone dtzReturn) 
{ 
    // convert to given timezone   
    DateTime dtClientTimezone = dateTime.withZoneRetainFields(dtzConversion); 
    // adjust time 
    dtClientTimezone = dtClientTimezone.withTime(hour, minute, second, 0); 

    if (dtzReturn != null) { 
     // convert to target timezone 
     dtClientTimezone = dtClientTimezone.withZoneRetainFields(dtzReturn); 
    } 

    return dtClientTimezone; 
} 

在我的例子dateTime是德国日期30.9.2015 22:00:00 UTC和dtzConversion是Europe/Berlin和dtzReturn是UTC随着时间的推移设置12:00:00结果是30.09.2015 12:00:00。但我期望01.10.2015 10:00:00因为30.09.2015 22:00:00 UTC到Europe/Berlin应该是01.10.2015 00:00:00。时间设置为'12：00：00'，其结果为01.10.2015 12:00:00。这在UTC是01.10.2015 10:00:00。我的错在哪里？

Answer 1

方法withZoneRetainFields不转换字段值。相反，它只是改变时区（以及基础毫秒，以便在新时区中的字段与旧时区中的值相同）。

您正在搜索的方法是withZone，其中调整字段：

public static DateTime convertDateTimeToTimeZone(final DateTime dateTime, final int hour, final int minute, 
     final int second, 
     final DateTimeZone dtzConversion, final DateTimeZone dtzReturn) 
{ 
    // convert to given timezone   
    DateTime dtClientTimezone = dateTime.withZone(dtzConversion); 
    // adjust time 
    dtClientTimezone = dtClientTimezone.withTime(hour, minute, second, 0); 

    if (dtzReturn != null) { 
     // convert to target timezone 
     dtClientTimezone = dtClientTimezone.withZone(dtzReturn); 
    } 

    return dtClientTimezone; 
} 

public static void main(String[] args) 
{ 
    DateTime parse = DateTime.parse("2015-09-30T22:00:00Z"); 
    DateTime convertDateTimeToTimeZone = convertDateTimeToTimeZone(parse, 12, 0, 0, DateTimeZone.forOffsetHours(2), DateTimeZone.UTC); 
    System.out.println(convertDateTimeToTimeZone); 
} 

结果：

2015-10-01T10：00：00.000Z