1 package org.apache.lucene.document;
4 * Licensed to the Apache Software Foundation (ASF) under one or more
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20 import org.apache.lucene.search.PrefixQuery;
21 import org.apache.lucene.search.TermRangeQuery;
22 import org.apache.lucene.search.NumericRangeQuery; // for javadocs
23 import org.apache.lucene.util.NumericUtils; // for javadocs
25 import java.util.Date; // for javadoc
26 import java.util.Calendar; // for javadoc
28 // do not remove in 3.0, needed for reading old indexes!
31 * Provides support for converting dates to strings and vice-versa.
32 * The strings are structured so that lexicographic sorting orders by date,
33 * which makes them suitable for use as field values and search terms.
35 * <P>Note that this class saves dates with millisecond granularity,
36 * which is bad for {@link TermRangeQuery} and {@link PrefixQuery}, as those
37 * queries are expanded to a BooleanQuery with a potentially large number
38 * of terms when searching. Thus you might want to use
39 * {@link DateTools} instead.
42 * Note: dates before 1970 cannot be used, and therefore cannot be
43 * indexed when using this class. See {@link DateTools} for an
44 * alternative without such a limitation.
47 * Another approach is {@link NumericUtils}, which provides
48 * a sortable binary representation (prefix encoded) of numeric values, which
50 * For indexing a {@link Date} or {@link Calendar}, just get the unix timestamp as
51 * <code>long</code> using {@link Date#getTime} or {@link Calendar#getTimeInMillis} and
52 * index this as a numeric value with {@link NumericField}
53 * and use {@link NumericRangeQuery} to query it.
55 * @deprecated If you build a new index, use {@link DateTools} or
56 * {@link NumericField} instead.
57 * This class is included for use with existing
58 * indices and will be removed in a future release (possibly Lucene 4.0).
61 public class DateField {
63 private DateField() {}
65 // make date strings long enough to last a millenium
66 private static int DATE_LEN = Long.toString(1000L*365*24*60*60*1000,
67 Character.MAX_RADIX).length();
69 public static String MIN_DATE_STRING() {
70 return timeToString(0);
73 public static String MAX_DATE_STRING() {
74 char[] buffer = new char[DATE_LEN];
75 char c = Character.forDigit(Character.MAX_RADIX-1, Character.MAX_RADIX);
76 for (int i = 0 ; i < DATE_LEN; i++)
78 return new String(buffer);
82 * Converts a Date to a string suitable for indexing.
83 * @throws RuntimeException if the date specified in the
84 * method argument is before 1970
86 public static String dateToString(Date date) {
87 return timeToString(date.getTime());
90 * Converts a millisecond time to a string suitable for indexing.
91 * @throws RuntimeException if the time specified in the
92 * method argument is negative, that is, before 1970
94 public static String timeToString(long time) {
96 throw new RuntimeException("time '" + time + "' is too early, must be >= 0");
98 String s = Long.toString(time, Character.MAX_RADIX);
100 if (s.length() > DATE_LEN)
101 throw new RuntimeException("time '" + time + "' is too late, length of string " +
102 "representation must be <= " + DATE_LEN);
104 // Pad with leading zeros
105 if (s.length() < DATE_LEN) {
106 StringBuilder sb = new StringBuilder(s);
107 while (sb.length() < DATE_LEN)
115 /** Converts a string-encoded date into a millisecond time. */
116 public static long stringToTime(String s) {
117 return Long.parseLong(s, Character.MAX_RADIX);
119 /** Converts a string-encoded date into a Date object. */
120 public static Date stringToDate(String s) {
121 return new Date(stringToTime(s));