我使用Apache common的DurationFormatUtils，就像这样:

DurationFormatUtils.formatDuration(millis, "**H:mm:ss**", true);

如果你不想拖进库，使用Formatter或相关的快捷方式就足够简单了。给定整数秒数s:

  String.format("%d:%02d:%02d", s / 3600, (s % 3600) / 60, (s % 60));

那么下面的函数呢 + H: MM: SS 或 + H: MM: SS.sss

public static String formatInterval(final long interval, boolean millisecs )
{
    final long hr = TimeUnit.MILLISECONDS.toHours(interval);
    final long min = TimeUnit.MILLISECONDS.toMinutes(interval) %60;
    final long sec = TimeUnit.MILLISECONDS.toSeconds(interval) %60;
    final long ms = TimeUnit.MILLISECONDS.toMillis(interval) %1000;
    if( millisecs ) {
        return String.format("%02d:%02d:%02d.%03d", hr, min, sec, ms);
    } else {
        return String.format("%02d:%02d:%02d", hr, min, sec );
    }
}

这个答案只使用Duration方法，适用于Java 8:

public static String format(Duration d) {
    long days = d.toDays();
    d = d.minusDays(days);
    long hours = d.toHours();
    d = d.minusHours(hours);
    long minutes = d.toMinutes();
    d = d.minusMinutes(minutes);
    long seconds = d.getSeconds() ;
    return 
            (days ==  0?"":days+" days,")+ 
            (hours == 0?"":hours+" hours,")+ 
            (minutes ==  0?"":minutes+" minutes,")+ 
            (seconds == 0?"":seconds+" seconds,");
}

在scala中，不需要库:

def prettyDuration(str:List[String],seconds:Long):List[String]={
  seconds match {
    case t if t < 60 => str:::List(s"${t} seconds")
    case t if (t >= 60 && t< 3600 ) => List(s"${t / 60} minutes"):::prettyDuration(str, t%60)
    case t if (t >= 3600 && t< 3600*24 ) => List(s"${t / 3600} hours"):::prettyDuration(str, t%3600)
    case t if (t>= 3600*24 ) => List(s"${t / (3600*24)} days"):::prettyDuration(str, t%(3600*24))
  }
}
val dur = prettyDuration(List.empty[String], 12345).mkString("")

使用这个func

private static String strDuration(long duration) {
    int ms, s, m, h, d;
    double dec;
    double time = duration * 1.0;

    time = (time / 1000.0);
    dec = time % 1;
    time = time - dec;
    ms = (int)(dec * 1000);

    time = (time / 60.0);
    dec = time % 1;
    time = time - dec;
    s = (int)(dec * 60);

    time = (time / 60.0);
    dec = time % 1;
    time = time - dec;
    m = (int)(dec * 60);

    time = (time / 24.0);
    dec = time % 1;
    time = time - dec;
    h = (int)(dec * 24);
    
    d = (int)time;
    
    return (String.format("%d d - %02d:%02d:%02d.%03d", d, h, m, s, ms));
}