我正在用 Java Swing 制作模拟时钟。要计算我需要的时钟指针角度:
- 我可以得到的 UTC 时间(以毫秒为单位)
System.currentTimeMillis()
- 时区偏移
- 时区夏令时节省。
对于 2) 和 3) 我想使用
TimeZone.getDefault().getRawOffset()
and TimeZone.getDefault().getDSTSavings()
。
但无论当前日期是在冬季/夏季时间,getDSTSavings()
总是返回。
看起来它只检查该区域是否正在管理中,如果是,则返回。
这是一个错误吗?
如果不是,那么在毫秒内获得当前校正的唯一方法是使用 Calendar 实例,例如:? 3600000
DST
3600000
0
getDSTSavings()
DST
Calendar.getInstance.get(Calendar.DST_OFFSET)
Calendar cal1 = Calendar.getInstance(TimeZone.getDefault()); //currentZone: CET/CEST +1/+2, GMT+1:00
System.out.println("System time, " + System.currentTimeMillis()); //UTC current milis
System.out.println("Calendar time, " + cal1.getTime().getTime()); //UTC current milis
System.out.println("Calendar milis, " + cal1.getTimeInMillis()); //UTC current milis
System.out.println("Calendar Zone Offset: " + cal1.get(Calendar.ZONE_OFFSET));
System.out.println("Calendar DST Offset: " + cal1.get(Calendar.DST_OFFSET));
System.out.println("Calendar Zone Offset: " + cal1.getTimeZone().getRawOffset());
System.out.println("Calendar DST Offset: " + cal1.getTimeZone().getDSTSavings());
System.out.println("");
// Winter time, CET
cal1.set(2010, 11, 15, 14, 15, 5);
System.out.println("Calendar milis, " + cal1.getTimeInMillis()); //UTC
System.out.println("Calendar Zone Offset: " + cal1.get(Calendar.ZONE_OFFSET)); // 3600000 correct
System.out.println("Calendar DST Offset: " + cal1.get(Calendar.DST_OFFSET)); // 0 correct
System.out.println("Calendar Zone Offset: " + cal1.getTimeZone().getRawOffset()); // 3600000 correct
System.out.println("Calendar DST Offset: " + cal1.getTimeZone().getDSTSavings()); // 3600000 wrong !!!
System.out.println("");
// Summer time - CEST
cal1.set(2010, 8, 15, 14, 15, 5);
System.out.println("Calendar milis, " + cal1.getTimeInMillis()); //UTC
System.out.println("Calendar Zone Offset: " + cal1.get(Calendar.ZONE_OFFSET)); // 3600000 correct
System.out.println("Calendar DST Offset: " + cal1.get(Calendar.DST_OFFSET)); // 3600000 correct
System.out.println("Calendar Zone Offset: " + cal1.getTimeZone().getRawOffset()); // 3600000 correct
System.out.println("Calendar DST Offset: " + cal1.getTimeZone().getDSTSavings()); // 3600000 correct