Package org.apache.lucene.document

Class DateTools

java.lang.Object
org.apache.lucene.document.DateTools
public class DateTools extends Object
Provides support for converting dates to strings and vice-versa. The strings are structured so that lexicographic sorting orders them by date, which makes them suitable for use as field values and search terms.

This class also helps you to limit the resolution of your dates. Do not save dates with a finer resolution than you really need, as then TermRangeQuery and PrefixQuery will require more memory and become slower.

Another approach is NumericUtils, which provides a sortable binary representation (prefix encoded) of numeric values, which date/time are. For indexing a Date or Calendar, just get the unix timestamp as long using Date.getTime() or Calendar.getTimeInMillis() and index this as a numeric value with LongField and use NumericRangeQuery to query it.

  • Method Details

    • dateToString

      public static String dateToString(Date date, DateTools.Resolution resolution)
      Converts a Date to a string suitable for indexing.
      Parameters:
      date - the date to be converted
      resolution - the desired resolution, see round(Date, DateTools.Resolution)
      Returns:
      a string in format yyyyMMddHHmmssSSS or shorter, depending on resolution; using GMT as timezone

    • timeToString

      public static String timeToString(long time, DateTools.Resolution resolution)
      Converts a millisecond time to a string suitable for indexing.
      Parameters:
      time - the date expressed as milliseconds since January 1, 1970, 00:00:00 GMT
      resolution - the desired resolution, see round(long, DateTools.Resolution)
      Returns:
      a string in format yyyyMMddHHmmssSSS or shorter, depending on resolution; using GMT as timezone

    • stringToTime

      public static long stringToTime(String dateString) throws ParseException
      Converts a string produced by timeToString or dateToString back to a time, represented as the number of milliseconds since January 1, 1970, 00:00:00 GMT.
      Parameters:
      dateString - the date string to be converted
      Returns:
      the number of milliseconds since January 1, 1970, 00:00:00 GMT
      Throws:
      ParseException - if dateString is not in the expected format

    • stringToDate

      public static Date stringToDate(String dateString) throws ParseException
      Converts a string produced by timeToString or dateToString back to a time, represented as a Date object.
      Parameters:
      dateString - the date string to be converted
      Returns:
      the parsed time as a Date object
      Throws:
      ParseException - if dateString is not in the expected format

    • round

      public static Date round(Date date, DateTools.Resolution resolution)
      Limit a date's resolution. For example, the date 2004-09-21 13:50:11 will be changed to 2004-09-01 00:00:00 when using Resolution.MONTH.
      Parameters:
      resolution - The desired resolution of the date to be returned
      Returns:
      the date with all values more precise than resolution set to 0 or 1

    • round

      public static long round(long time, DateTools.Resolution resolution)
      Limit a date's resolution. For example, the date 1095767411000 (which represents 2004-09-21 13:50:11) will be changed to 1093989600000 (2004-09-01 00:00:00) when using Resolution.MONTH.
      Parameters:
      resolution - The desired resolution of the date to be returned
      Returns:
      the date with all values more precise than resolution set to 0 or 1, expressed as milliseconds since January 1, 1970, 00:00:00 GMT