基于Lucene 2.1研究：时间的处理

基于Lucene 2.1研究：时间的处理

   Java版的Lucene对时间的处理和.Net版中的有很大不同，下面我给出org.apache.lucene.document包下DateTools类的.Net完整实现。
   public class DateTools
    {
        private static readonly string YEAR_FORMAT = "yyyy";
        private static readonly string MONTH_FORMAT = "yyyyMM";
        private static readonly string DAY_FORMAT = "yyyyMMdd";
        private static readonly string HOUR_FORMAT = "yyyyMMddHH";
        private static readonly string MINUTE_FORMAT = "yyyyMMddHHmm";
        private static readonly string SECOND_FORMAT = "yyyyMMddHHmmss";
        private static readonly string MILLISECOND_FORMAT = "yyyyMMddHHmmssfff";
        public static readonly DateTime BASE_UNIVERSAL_TIME = DateTime.Parse("January 1, 1970, 00:00:00 GMT").ToUniversalTime();

 
        public static string TimeToString(long l, Resolution resolution)
        {
            DateTime dt = LongToDateTime(l);

            string result = string .Empty ;

            switch (resolution)
            {
                case Resolution.YEAR:
                    result = dt.ToString(YEAR_FORMAT);

                    break;
                case Resolution.MONTH:
                    result = dt.ToString(MONTH_FORMAT);

                    break;
                case Resolution.DAY:
                    result = dt.ToString(DAY_FORMAT);

                    break;
                case Resolution.HOUR:
                    result = dt.ToString(HOUR_FORMAT);

                    break;
                case Resolution.MINUTE:
                    result = dt.ToString(MINUTE_FORMAT);

                    break;
                case Resolution.SECOND:
                    result = dt.ToString(SECOND_FORMAT);

                    break;
                case Resolution.MILLISECOND:
                    result = dt.ToString(MILLISECOND_FORMAT);

                    break;
            }

            return result;
        }

        public static string TimeToString(DateTime time, Resolution resolution)
        {
            return TimeToString(DateTimeToLong(time), resolution);
        }

        public static long Round(long time, Resolution resolution)
        {
            DateTime dt = BASE_UNIVERSAL_TIME.AddMilliseconds(time).ToUniversalTime();

            switch (resolution)
            {
                case Resolution.YEAR:
                    dt = dt.AddMonths(1 - dt.Month).AddDays(1 - dt.Day).AddHours(0 - dt.Hour).AddMinutes(0 - dt.Minute).AddSeconds(0 - dt.Second).AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.MONTH:
                    dt = dt.AddDays(1 - dt.Day).AddHours(0 - dt.Hour).AddMinutes(0 - dt.Minute).AddSeconds(0 - dt.Second).AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.DAY:
                    dt = dt.AddHours(0 - dt.Hour).AddMinutes(0 - dt.Minute).AddSeconds(0 - dt.Second).AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.HOUR:
                   dt = dt.AddMinutes(0 - dt.Minute).AddSeconds(0 - dt.Second).AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.MINUTE:
                    dt = dt.AddSeconds(0 - dt.Second) .AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.SECOND:
                    dt = dt.AddMilliseconds(0 - dt.Millisecond);

                    break;
                case Resolution.MILLISECOND:
                    break;
            }

            return DateTimeToLong(dt);
        }

        public static DateTime Round(DateTime date, Resolution resolution)
        {
            return LongToDateTime(Round(DateTimeToLong(date), resolution));
        }

        public static long DateTimeToLong(DateTime time)
        {
            return (long)(time.ToUniversalTime() - BASE_UNIVERSAL_TIME).TotalMilliseconds;
        }

        public static DateTime LongToDateTime(long l)
        {
            return BASE_UNIVERSAL_TIME.AddMilliseconds(l).ToUniversalTime();
        }

        public enum Resolution
        {
            YEAR,
            MONTH,
            DAY,
            HOUR,
            MINUTE,
            SECOND,
            MILLISECOND
        }
    }