Java 如何在Joda时间内检测不明确的DST重叠？

在中，可以很容易地使用该方法来判断本地日期和时间是否无效，因为它落入了前向日光节约时间转换产生的间隙

DateTimeZone zone = DateTimeZone.forID("America/New_York");
LocalDateTime ldt = new LocalDateTime(2013, 3, 10, 2, 0);
boolean inGap = zone.isLocalDateTimeGap(ldt);  // true

但是如何检测回退过渡？换句话说，如果本地日期和时间可能因为重叠而模棱两可，您如何检测？我希望类似于

zone.isLocalDateTimeOverlap

，但它并不存在。如果有，我会这样使用它：

DateTimeZone zone = DateTimeZone.forID("America/New_York");
LocalDateTime ldt = new LocalDateTime(2013, 11, 3, 1, 0);
boolean overlaps = zone.isLocalDateTimeOverlap(ldt);  // true

Joda Time文档清楚地表明，如果转换过程中出现重叠，除非另有说明，否则将采用更早的可能性。但它没有说明如何检测这种行为。

利用

public static boolean isInOverlap(LocalDateTime ldt, DateTimeZone dtz) {
    DateTime dt1 = ldt.toDateTime(dtz).withEarlierOffsetAtOverlap();
    DateTime dt2 = dt1.withLaterOffsetAtOverlap();
    return dt1.getMillis() != dt2.getMillis();
}


public static void test() {
    // CET DST rolls back at 2011-10-30 2:59:59 (+02) to 2011-10-30 2:00:00 (+01)
    final DateTimeZone dtz = DateTimeZone.forID("CET");
    LocalDateTime ldt1 = new LocalDateTime(2011,10,30,1,50,0,0); // not in overlap
    LocalDateTime ldt2 = new LocalDateTime(2011,10,30,2,50,0,0); // in overlap
    System.out.println(ldt1 + " is in overlap? " + isInOverlap(ldt1, dtz)); 
    System.out.println(ldt2 + " is in overlap? " + isInOverlap(ldt2, dtz)); 
}