package org.apache.lucene.document;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
/**
* 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.
*
* <P>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
* RangeQuery and PrefixQuery will require more memory and become slower.
*
* <P>Compared to {@link DateField} the strings generated by the methods
* in this class take slightly more space, unless your selected resolution
* is set to <code>Resolution.DAY</code> or lower.
*/
public class DateTools {
private final static TimeZone GMT = TimeZone.getTimeZone("GMT");
private static final SimpleDateFormat YEAR_FORMAT = new SimpleDateFormat("yyyy");
private static final SimpleDateFormat MONTH_FORMAT = new SimpleDateFormat("yyyyMM");
private static final SimpleDateFormat DAY_FORMAT = new SimpleDateFormat("yyyyMMdd");
private static final SimpleDateFormat HOUR_FORMAT = new SimpleDateFormat("yyyyMMddHH");
private static final SimpleDateFormat MINUTE_FORMAT = new SimpleDateFormat("yyyyMMddHHmm");
private static final SimpleDateFormat SECOND_FORMAT = new SimpleDateFormat("yyyyMMddHHmmss");
private static final SimpleDateFormat MILLISECOND_FORMAT = new SimpleDateFormat("yyyyMMddHHmmssSSS");
static {
// times need to be normalized so the value doesn't depend on the
// location the index is created/used:
YEAR_FORMAT.setTimeZone(GMT);
MONTH_FORMAT.setTimeZone(GMT);
DAY_FORMAT.setTimeZone(GMT);
HOUR_FORMAT.setTimeZone(GMT);
MINUTE_FORMAT.setTimeZone(GMT);
SECOND_FORMAT.setTimeZone(GMT);
MILLISECOND_FORMAT.setTimeZone(GMT);
}
// cannot create, the class has static methods only
private DateTools() {}
/**
* Converts a Date to a string suitable for indexing.
*
* @param date the date to be converted
* @param resolution the desired resolution, see
* {@link #round(Date, DateTools.Resolution)}
* @return a string in format <code>yyyyMMddHHmmssSSS</code> or shorter,
* depeding on <code>resolution</code>; using UTC as timezone
*/
public static String dateToString(Date date, Resolution resolution) {
return timeToString(date.getTime(), resolution);
}
/**
* Converts a millisecond time to a string suitable for indexing.
*
* @param time the date expressed as milliseconds since January 1, 1970, 00:00:00 GMT
* @param resolution the desired resolution, see
* {@link #round(long, DateTools.Resolution)}
* @return a string in format <code>yyyyMMddHHmmssSSS</code> or shorter,
* depeding on <code>resolution</code>; using UTC as timezone
*/
public static String timeToString(long time, Resolution resolution) {
Calendar cal = Calendar.getInstance(GMT);
//protected in JDK's prior to 1.4
//cal.setTimeInMillis(round(time, resolution));
cal.setTime(new Date(round(time, resolution)));
String result;
if (resolution == Resolution.YEAR) {
synchronized (YEAR_FORMAT) {
result = YEAR_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.MONTH) {
synchronized (MONTH_FORMAT) {
result = MONTH_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.DAY) {
synchronized (DAY_FORMAT) {
result = DAY_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.HOUR) {
synchronized (HOUR_FORMAT) {
result = HOUR_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.MINUTE) {
synchronized (MINUTE_FORMAT) {
result = MINUTE_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.SECOND) {
synchronized (SECOND_FORMAT) {
result = SECOND_FORMAT.format(cal.getTime());
}
} else if (resolution == Resolution.MILLISECOND) {
synchronized (MILLISECOND_FORMAT) {
result = MILLISECOND_FORMAT.format(cal.getTime());
}
} else {
throw new IllegalArgumentException("unknown resolution " + resolution);
}
return result;
}
/**
* Converts a string produced by <code>timeToString</code> or
* <code>dateToString</code> back to a time, represented as the
* number of milliseconds since January 1, 1970, 00:00:00 GMT.
*
* @param dateString the date string to be converted
* @return the number of milliseconds since January 1, 1970, 00:00:00 GMT
* @throws ParseException if <code>dateString</code> is not in the
* expected format
*/
public static long stringToTime(String dateString) throws ParseException {
return stringToDate(dateString).getTime();
}
/**
* Converts a string produced by <code>timeToString</code> or
* <code>dateToString</code> back to a time, represented as a
* Date object.
*
* @param dateString the date string to be converted
* @return the parsed time as a Date object
* @throws ParseException if <code>dateString</code> is not in the
* expected format
*/
public static Date stringToDate(String dateString) throws ParseException {
Date date;
if (dateString.length() == 4) {
synchronized (YEAR_FORMAT) {
date = YEAR_FORMAT.parse(dateString);
}
} else if (dateString.length() == 6) {
synchronized (MONTH_FORMAT) {
date = MONTH_FORMAT.parse(dateString);
}
} else if (dateString.length() == 8) {
synchronized (DAY_FORMAT) {
date = DAY_FORMAT.parse(dateString);
}
} else if (dateString.length() == 10) {
synchronized (HOUR_FORMAT) {
date = HOUR_FORMAT.parse(dateString);
}
} else if (dateString.length() == 12) {
synchronized (MINUTE_FORMAT) {
date = MINUTE_FORMAT.parse(dateString);
}
} else if (dateString.length() == 14) {
synchronized (SECOND_FORMAT) {
date = SECOND_FORMAT.parse(dateString);
}
} else if (dateString.length() == 17) {
synchronized (MILLISECOND_FORMAT) {
date = MILLISECOND_FORMAT.parse(dateString);
}
} else {
throw new ParseException("Input is not valid date string: " + dateString, 0);
}
return date;
}
/**
* Limit a date's resolution. For example, the date <code>2004-09-21 13:50:11</code>
* will be changed to <code>2004-09-01 00:00:00</code> when using
* <code>Resolution.MONTH</code>.
*
* @param resolution The desired resolution of the date to be returned
* @return the date with all values more precise than <code>resolution</code>
* set to 0 or 1
*/
public static Date round(Date date, Resolution resolution) {
return new Date(round(date.getTime(), resolution));
}
/**
* Limit a date's resolution. For example, the date <code>1095767411000</code>
* (which represents 2004-09-21 13:50:11) will be changed to
* <code>1093989600000</code> (2004-09-01 00:00:00) when using
* <code>Resolution.MONTH</code>.
*
* @param resolution The desired resolution of the date to be returned
* @return the date with all values more precise than <code>resolution</code>
* set to 0 or 1, expressed as milliseconds since January 1, 1970, 00:00:00 GMT
*/
public static long round(long time, Resolution resolution) {
Calendar cal = Calendar.getInstance(GMT);
// protected in JDK's prior to 1.4
//cal.setTimeInMillis(time);
cal.setTime(new Date(time));
if (resolution == Resolution.YEAR) {
cal.set(Calendar.MONTH, 0);
cal.set(Calendar.DAY_OF_MONTH, 1);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.MONTH) {
cal.set(Calendar.DAY_OF_MONTH, 1);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.DAY) {
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.HOUR) {
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.MINUTE) {
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.SECOND) {
cal.set(Calendar.MILLISECOND, 0);
} else if (resolution == Resolution.MILLISECOND) {
// don't cut off anything
} else {
throw new IllegalArgumentException("unknown resolution " + resolution);
}
return cal.getTime().getTime();
}
/** Specifies the time granularity. */
public static class Resolution {
public static final Resolution YEAR = new Resolution("year");
public static final Resolution MONTH = new Resolution("month");
public static final Resolution DAY = new Resolution("day");
public static final Resolution HOUR = new Resolution("hour");
public static final Resolution MINUTE = new Resolution("minute");
public static final Resolution SECOND = new Resolution("second");
public static final Resolution MILLISECOND = new Resolution("millisecond");
private String resolution;
private Resolution() {
}
private Resolution(String resolution) {
this.resolution = resolution;
}
public String toString() {
return resolution;
}
}
}
|
