com.ibm.icu.util.ChineseCalendar Maven / Gradle / Ivy
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*********************************************************************
* Copyright (C) 2000-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*********************************************************************
*/
package com.ibm.icu.util;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.Date;
import java.util.Locale;
import com.ibm.icu.impl.CalendarAstronomer;
import com.ibm.icu.impl.CalendarCache;
import com.ibm.icu.text.DateFormat;
import com.ibm.icu.util.ULocale.Category;
/**
* ChineseCalendar is a concrete subclass of {@link Calendar}
* that implements a traditional Chinese calendar. The traditional Chinese
* calendar is a lunisolar calendar: Each month starts on a new moon, and
* the months are numbered according to solar events, specifically, to
* guarantee that month 11 always contains the winter solstice. In order
* to accomplish this, leap months are inserted in certain years. Leap
* months are numbered the same as the month they follow. The decision of
* which month is a leap month depends on the relative movements of the sun
* and moon.
*
* All astronomical computations are performed with respect to a time
* zone of GMT+8:00 and a longitude of 120 degrees east. Although some
* calendars implement a historically more accurate convention of using
* Beijing's local longitude (116 degrees 25 minutes east) and time zone
* (GMT+7:45:40) for dates before 1929, we do not implement this here.
*
*
Years are counted in two different ways in the Chinese calendar. The
* first method is by sequential numbering from the 61st year of the reign
* of Huang Di, 2637 BCE, which is designated year 1 on the Chinese
* calendar. The second method uses 60-year cycles from the same starting
* point, which is designated year 1 of cycle 1. In this class, the
* EXTENDED_YEAR field contains the sequential year count.
* The ERA field contains the cycle number, and the
* YEAR field contains the year of the cycle, a value between
* 1 and 60.
*
*
There is some variation in what is considered the starting point of
* the calendar, with some sources starting in the first year of the reign
* of Huang Di, rather than the 61st. This gives continuous year numbers
* 60 years greater and cycle numbers one greater than what this class
* implements.
*
*
Because ChineseCalendar defines an additional field and
* redefines the way the ERA field is used, it requires a new
* format class, ChineseDateFormat. As always, use the
* methods DateFormat.getXxxInstance(Calendar cal,...) to
* obtain a formatter for this calendar.
*
*
References:
*
* - Dershowitz and Reingold, Calendrical Calculations,
* Cambridge University Press, 1997
*
* - Helmer Aslaksen's
*
* Chinese Calendar page
*
* - The
* Calendar FAQ
*
*
*
*
* This class should not be subclassed.
*
* ChineseCalendar usually should be instantiated using
* {@link com.ibm.icu.util.Calendar#getInstance(ULocale)} passing in a ULocale
* with the tag "@calendar=chinese".
*
* @see com.ibm.icu.util.Calendar
* @author Alan Liu
* @stable ICU 2.8
*/
public class ChineseCalendar extends Calendar {
// jdk1.4.2 serialver
private static final long serialVersionUID = 7312110751940929420L;
//------------------------------------------------------------------
// Developer Notes
//
// Time is represented as a scalar in two ways in this class. One is
// the usual UTC epoch millis, that is, milliseconds after January 1,
// 1970 Gregorian, 0:00:00.000 UTC. The other is in terms of 'local
// days.' This is the number of days after January 1, 1970 Gregorian,
// local to Beijing, China (since all computations of the Chinese
// calendar are done in Beijing). That is, 0 represents January 1,
// 1970 0:00 Asia/Shanghai. Conversion of local days to and from
// standard epoch milliseconds is accomplished by the daysToMillis()
// and millisToDays() methods.
//
// Several methods use caches to improve performance. Caches are at
// the object, not class level, under the assumption that typical
// usage will be to have one instance of ChineseCalendar at a time.
/**
* The start year of this Chinese calendar instance.
*/
private int epochYear;
/**
* The zone used for the astronomical calculation of this Chinese
* calendar instance.
*/
private TimeZone zoneAstro;
/**
* We have one instance per object, and we don't synchronize it because
* Calendar doesn't support multithreaded execution in the first place.
*/
private transient CalendarAstronomer astro = new CalendarAstronomer();
/**
* Cache that maps Gregorian year to local days of winter solstice.
* @see #winterSolstice
*/
private transient CalendarCache winterSolsticeCache = new CalendarCache();
/**
* Cache that maps Gregorian year to local days of Chinese new year.
* @see #newYear
*/
private transient CalendarCache newYearCache = new CalendarCache();
/**
* True if the current year is a leap year. Updated with each time to
* fields resolution.
* @see #computeChineseFields
*/
private transient boolean isLeapYear;
//------------------------------------------------------------------
// Constructors
//------------------------------------------------------------------
/**
* Construct a ChineseCalendar with the default time zone and locale.
* @stable ICU 2.8
*/
public ChineseCalendar() {
this(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT), CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Construct a ChineseCalendar with the give date set in the default time zone
* with the default locale.
* @param date The date to which the new calendar is set.
* @stable ICU 4.0
*/
public ChineseCalendar(Date date) {
this(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT), CHINESE_EPOCH_YEAR, CHINA_ZONE);
setTime(date);
}
/**
* Constructs a ChineseCalendar with the given date set
* in the default time zone with the default FORMAT locale.
*
* @param year The value used to set the calendar's {@link #YEAR YEAR} time field.
* @param month The value used to set the calendar's {@link #MONTH MONTH} time field.
* The value is 0-based. e.g., 0 for January.
* @param isLeapMonth The value used to set the Chinese calendar's {@link #IS_LEAP_MONTH}
* time field.
* @param date The value used to set the calendar's {@link #DATE DATE} time field.
* @see Category#FORMAT
* @stable ICU 4.0
*/
public ChineseCalendar(int year, int month, int isLeapMonth, int date) {
this(year, month, isLeapMonth, date, 0, 0, 0);
}
/**
* Constructs a ChineseCalendar with the given date
* and time set for the default time zone with the default FORMAT locale.
*
* @param year the value used to set the {@link #YEAR YEAR} time field in the calendar.
* @param month the value used to set the {@link #MONTH MONTH} time field in the calendar.
* Note that the month value is 0-based. e.g., 0 for January.
* @param isLeapMonth the value used to set the {@link #IS_LEAP_MONTH} time field
* in the calendar.
* @param date the value used to set the {@link #DATE DATE} time field in the calendar.
* @param hour the value used to set the {@link #HOUR_OF_DAY HOUR_OF_DAY} time field
* in the calendar.
* @param minute the value used to set the {@link #MINUTE MINUTE} time field
* in the calendar.
* @param second the value used to set the {@link #SECOND SECOND} time field
* in the calendar.
* @see Category#FORMAT
* @stable ICU 4.0
*/
public ChineseCalendar(int year, int month, int isLeapMonth, int date, int hour,
int minute, int second)
{
this(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT), CHINESE_EPOCH_YEAR, CHINA_ZONE);
// The current time is set at this point, so ERA field is already
// set to the current era.
// Then we need to clean up time fields
this.set(MILLISECOND, 0);
// Then, set the given field values.
this.set(YEAR, year);
this.set(MONTH, month);
this.set(IS_LEAP_MONTH, isLeapMonth);
this.set(DATE, date);
this.set(HOUR_OF_DAY, hour);
this.set(MINUTE, minute);
this.set(SECOND, second);
}
/**
* Constructs a ChineseCalendar with the given date set
* in the default time zone with the default FORMAT locale.
*
* @param era The value used to set the calendar's {@link #ERA ERA} time field.
* @param year The value used to set the calendar's {@link #YEAR YEAR} time field.
* @param month The value used to set the calendar's {@link #MONTH MONTH} time field.
* The value is 0-based. e.g., 0 for January.
* @param isLeapMonth The value used to set the Chinese calendar's {@link #IS_LEAP_MONTH}
* time field.
* @param date The value used to set the calendar's {@link #DATE DATE} time field.
* @see Category#FORMAT
* @stable ICU 4.6
*/
public ChineseCalendar(int era, int year, int month, int isLeapMonth, int date)
{
this(era, year, month, isLeapMonth, date, 0, 0, 0);
}
/**
* Constructs a ChineseCalendar with the given date
* and time set for the default time zone with the default FORMAT locale.
*
* @param era the value used to set the calendar's {@link #ERA ERA} time field.
* @param year the value used to set the {@link #YEAR YEAR} time field in the calendar.
* @param month the value used to set the {@link #MONTH MONTH} time field in the calendar.
* Note that the month value is 0-based. e.g., 0 for January.
* @param isLeapMonth the value used to set the {@link #IS_LEAP_MONTH} time field
* in the calendar.
* @param date the value used to set the {@link #DATE DATE} time field in the calendar.
* @param hour the value used to set the {@link #HOUR_OF_DAY HOUR_OF_DAY} time field
* in the calendar.
* @param minute the value used to set the {@link #MINUTE MINUTE} time field
* in the calendar.
* @param second the value used to set the {@link #SECOND SECOND} time field
* in the calendar.
* @see Category#FORMAT
* @stable ICU 4.6
*/
public ChineseCalendar(int era, int year, int month, int isLeapMonth, int date, int hour,
int minute, int second)
{
this(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT), CHINESE_EPOCH_YEAR, CHINA_ZONE);
// Set 0 to millisecond field
this.set(MILLISECOND, 0);
// Then, set the given field values.
this.set(ERA, era);
this.set(YEAR, year);
this.set(MONTH, month);
this.set(IS_LEAP_MONTH, isLeapMonth);
this.set(DATE, date);
this.set(HOUR_OF_DAY, hour);
this.set(MINUTE, minute);
this.set(SECOND, second);
}
/**
* Constructs a ChineseCalendar based on the current time
* in the default time zone with the given locale.
* @param aLocale The given locale
* @stable ICU 4.0
*/
public ChineseCalendar(Locale aLocale) {
this(TimeZone.forLocaleOrDefault(aLocale), ULocale.forLocale(aLocale), CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Construct a ChineseCalendar based on the current time
* in the given time zone with the default FORMAT locale.
* @param zone the given time zone
* @see Category#FORMAT
* @stable ICU 4.0
*/
public ChineseCalendar(TimeZone zone) {
this(zone, ULocale.getDefault(Category.FORMAT), CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Construct a ChineseCalendar based on the current time
* in the given time zone with the given locale.
* @param zone the given time zone
* @param aLocale the given locale
* @stable ICU 2.8
*/
public ChineseCalendar(TimeZone zone, Locale aLocale) {
this(zone, ULocale.forLocale(aLocale), CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Constructs a ChineseCalendar based on the current time
* in the default time zone with the given locale.
*
* @param locale the given ulocale
* @stable ICU 4.0
*/
public ChineseCalendar(ULocale locale) {
this(TimeZone.forULocaleOrDefault(locale), locale, CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Construct a ChineseCalendar based on the current time
* with the given time zone with the given locale.
* @param zone the given time zone
* @param locale the given ulocale
* @stable ICU 3.2
*/
public ChineseCalendar(TimeZone zone, ULocale locale) {
this(zone, locale, CHINESE_EPOCH_YEAR, CHINA_ZONE);
}
/**
* Construct a ChineseCalenar based on the current time
* with the given time zone, the locale, the epoch year and the time zone
* used for astronomical calculation.
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
protected ChineseCalendar(TimeZone zone, ULocale locale, int epochYear, TimeZone zoneAstroCalc) {
super(zone, locale);
this.epochYear = epochYear;
this.zoneAstro = zoneAstroCalc;
setTimeInMillis(System.currentTimeMillis());
}
//------------------------------------------------------------------
// Public constants
//------------------------------------------------------------------
/**
* Field indicating whether or not the current month is a leap month.
* Should have a value of 0 for non-leap months, and 1 for leap months.
* @stable ICU 2.8
*/
// public static int IS_LEAP_MONTH = BASE_FIELD_COUNT;
//------------------------------------------------------------------
// Calendar framework
//------------------------------------------------------------------
/**
* Array defining the limits of field values for this class. Field
* limits which are invariant with respect to calendar system and
* defined by Calendar are left blank.
*
* Notes:
*
* ERA 5000000 / 60 = 83333.
*
* MONTH There are 12 or 13 lunar months in a year. However, we always
* number them 0..11, with an intercalated, identically numbered leap
* month, when necessary.
*
* DAY_OF_YEAR In a non-leap year there are 353, 354, or 355 days. In
* a leap year there are 383, 384, or 385 days.
*
* WEEK_OF_YEAR The least maximum occurs if there are 353 days in the
* year, and the first 6 are the last week of the previous year. Then
* we have 49 full weeks and 4 days in the last week: 6 + 49*7 + 4 =
* 353. So the least maximum is 50. The maximum occurs if there are
* 385 days in the year, and WOY 1 extends 6 days into the prior year.
* Then there are 54 full weeks, and 6 days in the last week: 1 + 54*7
* + 6 = 385. The 6 days of the last week will fall into WOY 1 of the
* next year. Maximum is 55.
*
* WEEK_OF_MONTH In a 29 day month, if the first 7 days make up week 1
* that leaves 3 full weeks and 1 day at the end. The least maximum is
* thus 5. In a 30 days month, if the previous 6 days belong WOM 1 of
* this month, we have 4 full weeks and 1 days at the end (which
* technically will be WOM 1 of the next month, but will be reported by
* time->fields and hence by getActualMaximum as WOM 6 of this month).
* Maximum is 6.
*
* DAY_OF_WEEK_IN_MONTH In a 29 or 30 day month, there are 4 full weeks
* plus 1 or 2 days at the end, so the maximum is always 5.
*/
private static final int LIMITS[][] = {
// Minimum Greatest Least Maximum
// Minimum Maximum
{ 1, 1, 83333, 83333 }, // ERA
{ 1, 1, 60, 60 }, // YEAR
{ 0, 0, 11, 11 }, // MONTH
{ 1, 1, 50, 55 }, // WEEK_OF_YEAR
{/* */}, // WEEK_OF_MONTH
{ 1, 1, 29, 30 }, // DAY_OF_MONTH
{ 1, 1, 353, 385 }, // DAY_OF_YEAR
{/* */}, // DAY_OF_WEEK
{ -1, -1, 5, 5 }, // DAY_OF_WEEK_IN_MONTH
{/* */}, // AM_PM
{/* */}, // HOUR
{/* */}, // HOUR_OF_DAY
{/* */}, // MINUTE
{/* */}, // SECOND
{/* */}, // MILLISECOND
{/* */}, // ZONE_OFFSET
{/* */}, // DST_OFFSET
{ -5000000, -5000000, 5000000, 5000000 }, // YEAR_WOY
{/* */}, // DOW_LOCAL
{ -5000000, -5000000, 5000000, 5000000 }, // EXTENDED_YEAR
{/* */}, // JULIAN_DAY
{/* */}, // MILLISECONDS_IN_DAY
{ 0, 0, 1, 1 }, // IS_LEAP_MONTH
};
/**
* Override Calendar to return the limit value for the given field.
* @stable ICU 2.8
*/
protected int handleGetLimit(int field, int limitType) {
return LIMITS[field][limitType];
}
/**
* Implement abstract Calendar method to return the extended year
* defined by the current fields. This will use either the ERA and
* YEAR field as the cycle and year-of-cycle, or the EXTENDED_YEAR
* field as the continuous year count, depending on which is newer.
* @stable ICU 2.8
*/
protected int handleGetExtendedYear() {
int year;
if (newestStamp(ERA, YEAR, UNSET) <= getStamp(EXTENDED_YEAR)) {
year = internalGet(EXTENDED_YEAR, 1); // Default to year 1
} else {
int cycle = internalGet(ERA, 1) - 1; // 0-based cycle
// adjust to the instance specific epoch
year = cycle * 60 + internalGet(YEAR, 1) - (epochYear - CHINESE_EPOCH_YEAR);
}
return year;
}
/**
* Override Calendar method to return the number of days in the given
* extended year and month.
*
* Note: This method also reads the IS_LEAP_MONTH field to determine
* whether or not the given month is a leap month.
* @stable ICU 2.8
*/
protected int handleGetMonthLength(int extendedYear, int month) {
int thisStart = handleComputeMonthStart(extendedYear, month, true) -
EPOCH_JULIAN_DAY + 1; // Julian day -> local days
int nextStart = newMoonNear(thisStart + SYNODIC_GAP, true);
return nextStart - thisStart;
}
/**
* {@inheritDoc}
*
* @stable ICU 4.2
*/
protected DateFormat handleGetDateFormat(String pattern, String override, ULocale locale) {
// Note: ICU 50 or later versions no longer use ChineseDateFormat.
// The super class's handleGetDateFormat will create an instance of
// SimpleDateFormat which supports Chinese calendar date formatting
// since ICU 49.
//return new ChineseDateFormat(pattern, override, locale);
return super.handleGetDateFormat(pattern, override, locale);
}
/**
* Field resolution table that incorporates IS_LEAP_MONTH.
*/
static final int[][][] CHINESE_DATE_PRECEDENCE = {
{
{ DAY_OF_MONTH },
{ WEEK_OF_YEAR, DAY_OF_WEEK },
{ WEEK_OF_MONTH, DAY_OF_WEEK },
{ DAY_OF_WEEK_IN_MONTH, DAY_OF_WEEK },
{ WEEK_OF_YEAR, DOW_LOCAL },
{ WEEK_OF_MONTH, DOW_LOCAL },
{ DAY_OF_WEEK_IN_MONTH, DOW_LOCAL },
{ DAY_OF_YEAR },
{ RESOLVE_REMAP | DAY_OF_MONTH, IS_LEAP_MONTH },
},
{
{ WEEK_OF_YEAR },
{ WEEK_OF_MONTH },
{ DAY_OF_WEEK_IN_MONTH },
{ RESOLVE_REMAP | DAY_OF_WEEK_IN_MONTH, DAY_OF_WEEK },
{ RESOLVE_REMAP | DAY_OF_WEEK_IN_MONTH, DOW_LOCAL },
},
};
/**
* Override Calendar to add IS_LEAP_MONTH to the field resolution
* table.
* @stable ICU 2.8
*/
protected int[][][] getFieldResolutionTable() {
return CHINESE_DATE_PRECEDENCE;
}
/**
* Adjust this calendar to be delta months before or after a given
* start position, pinning the day of month if necessary. The start
* position is given as a local days number for the start of the month
* and a day-of-month. Used by add() and roll().
* @param newMoon the local days of the first day of the month of the
* start position (days after January 1, 1970 0:00 Asia/Shanghai)
* @param dom the 1-based day-of-month of the start position
* @param delta the number of months to move forward or backward from
* the start position
*/
private void offsetMonth(int newMoon, int dom, int delta) {
// Move to the middle of the month before our target month.
newMoon += (int) (CalendarAstronomer.SYNODIC_MONTH * (delta - 0.5));
// Search forward to the target month's new moon
newMoon = newMoonNear(newMoon, true);
// Find the target dom
int jd = newMoon + EPOCH_JULIAN_DAY - 1 + dom;
// Pin the dom. In this calendar all months are 29 or 30 days
// so pinning just means handling dom 30.
if (dom > 29) {
set(JULIAN_DAY, jd-1);
// TODO Fix this. We really shouldn't ever have to
// explicitly call complete(). This is either a bug in
// this method, in ChineseCalendar, or in
// Calendar.getActualMaximum(). I suspect the last.
complete();
if (getActualMaximum(DAY_OF_MONTH) >= dom) {
set(JULIAN_DAY, jd);
}
} else {
set(JULIAN_DAY, jd);
}
}
/**
* Override Calendar to handle leap months properly.
* @stable ICU 2.8
*/
public void add(int field, int amount) {
switch (field) {
case MONTH:
if (amount != 0) {
int dom = get(DAY_OF_MONTH);
int day = get(JULIAN_DAY) - EPOCH_JULIAN_DAY; // Get local day
int moon = day - dom + 1; // New moon
offsetMonth(moon, dom, amount);
}
break;
default:
super.add(field, amount);
break;
}
}
/**
* Override Calendar to handle leap months properly.
* @stable ICU 2.8
*/
public void roll(int field, int amount) {
switch (field) {
case MONTH:
if (amount != 0) {
int dom = get(DAY_OF_MONTH);
int day = get(JULIAN_DAY) - EPOCH_JULIAN_DAY; // Get local day
int moon = day - dom + 1; // New moon (start of this month)
// Note throughout the following: Months 12 and 1 are never
// followed by a leap month (D&R p. 185).
// Compute the adjusted month number m. This is zero-based
// value from 0..11 in a non-leap year, and from 0..12 in a
// leap year.
int m = get(MONTH); // 0-based month
if (isLeapYear) { // (member variable)
if (get(IS_LEAP_MONTH) == 1) {
++m;
} else {
// Check for a prior leap month. (In the
// following, month 0 is the first month of the
// year.) Month 0 is never followed by a leap
// month, and we know month m is not a leap month.
// moon1 will be the start of month 0 if there is
// no leap month between month 0 and month m;
// otherwise it will be the start of month 1.
int moon1 = moon -
(int) (CalendarAstronomer.SYNODIC_MONTH * (m - 0.5));
moon1 = newMoonNear(moon1, true);
if (isLeapMonthBetween(moon1, moon)) {
++m;
}
}
}
// Now do the standard roll computation on m, with the
// allowed range of 0..n-1, where n is 12 or 13.
int n = isLeapYear ? 13 : 12; // Months in this year
int newM = (m + amount) % n;
if (newM < 0) {
newM += n;
}
if (newM != m) {
offsetMonth(moon, dom, newM - m);
}
}
break;
default:
super.roll(field, amount);
break;
}
}
//------------------------------------------------------------------
// Support methods and constants
//------------------------------------------------------------------
/**
* The start year of the Chinese calendar, the 61st year of the reign
* of Huang Di. Some sources use the first year of his reign,
* resulting in EXTENDED_YEAR values 60 years greater and ERA (cycle)
* values one greater.
*/
private static final int CHINESE_EPOCH_YEAR = -2636; // Gregorian year
/**
* The time zone used for performing astronomical computations.
* Some sources use a different historically accurate
* offset of GMT+7:45:40 for years before 1929; we do not do this.
*/
private static final TimeZone CHINA_ZONE = new SimpleTimeZone(8 * ONE_HOUR, "CHINA_ZONE").freeze();
/**
* Value to be added or subtracted from the local days of a new moon to
* get close to the next or prior new moon, but not cross it. Must be
* >= 1 and < CalendarAstronomer.SYNODIC_MONTH.
*/
private static final int SYNODIC_GAP = 25;
/**
* Convert local days to UTC epoch milliseconds.
* This is not an accurate conversion in terms that getTimezoneOffset
* takes the milliseconds in GMT (not local time). In theory, more
* accurate algorithm can be implemented but practically we do not need
* to go through that complication as long as the historically timezone
* changes did not happen around the 'tricky' new moon (new moon around
* the midnight).
*
* @param days days after January 1, 1970 0:00 in the astronomical base zone
* @return milliseconds after January 1, 1970 0:00 GMT
*/
private final long daysToMillis(int days) {
long millis = days * ONE_DAY;
return millis - zoneAstro.getOffset(millis);
}
/**
* Convert UTC epoch milliseconds to local days.
* @param millis milliseconds after January 1, 1970 0:00 GMT
* @return days days after January 1, 1970 0:00 in the astronomical base zone
*/
private final int millisToDays(long millis) {
return (int) floorDivide(millis + zoneAstro.getOffset(millis), ONE_DAY);
}
//------------------------------------------------------------------
// Astronomical computations
//------------------------------------------------------------------
/**
* Return the major solar term on or after December 15 of the given
* Gregorian year, that is, the winter solstice of the given year.
* Computations are relative to Asia/Shanghai time zone.
* @param gyear a Gregorian year
* @return days after January 1, 1970 0:00 Asia/Shanghai of the
* winter solstice of the given year
*/
private int winterSolstice(int gyear) {
long cacheValue = winterSolsticeCache.get(gyear);
if (cacheValue == CalendarCache.EMPTY) {
// In books December 15 is used, but it fails for some years
// using our algorithms, e.g.: 1298 1391 1492 1553 1560. That
// is, winterSolstice(1298) starts search at Dec 14 08:00:00
// PST 1298 with a final result of Dec 14 10:31:59 PST 1299.
long ms = daysToMillis(computeGregorianMonthStart(gyear, DECEMBER) +
1 - EPOCH_JULIAN_DAY);
astro.setTime(ms);
// Winter solstice is 270 degrees solar longitude aka Dongzhi
long solarLong = astro.getSunTime(CalendarAstronomer.WINTER_SOLSTICE,
true);
cacheValue = millisToDays(solarLong);
winterSolsticeCache.put(gyear, cacheValue);
}
return (int) cacheValue;
}
/**
* Return the closest new moon to the given date, searching either
* forward or backward in time.
* @param days days after January 1, 1970 0:00 Asia/Shanghai
* @param after if true, search for a new moon on or after the given
* date; otherwise, search for a new moon before it
* @return days after January 1, 1970 0:00 Asia/Shanghai of the nearest
* new moon after or before days
*/
private int newMoonNear(int days, boolean after) {
astro.setTime(daysToMillis(days));
long newMoon = astro.getMoonTime(CalendarAstronomer.NEW_MOON, after);
return millisToDays(newMoon);
}
/**
* Return the nearest integer number of synodic months between
* two dates.
* @param day1 days after January 1, 1970 0:00 Asia/Shanghai
* @param day2 days after January 1, 1970 0:00 Asia/Shanghai
* @return the nearest integer number of months between day1 and day2
*/
private int synodicMonthsBetween(int day1, int day2) {
return (int) Math.round((day2 - day1) / CalendarAstronomer.SYNODIC_MONTH);
}
/**
* Return the major solar term on or before a given date. This
* will be an integer from 1..12, with 1 corresponding to 330 degrees,
* 2 to 0 degrees, 3 to 30 degrees,..., and 12 to 300 degrees.
* @param days days after January 1, 1970 0:00 Asia/Shanghai
*/
private int majorSolarTerm(int days) {
astro.setTime(daysToMillis(days));
// Compute (floor(solarLongitude / (pi/6)) + 2) % 12
int term = ((int) Math.floor(6 * astro.getSunLongitude() / Math.PI) + 2) % 12;
if (term < 1) {
term += 12;
}
return term;
}
/**
* Return true if the given month lacks a major solar term.
* @param newMoon days after January 1, 1970 0:00 Asia/Shanghai of a new
* moon
*/
private boolean hasNoMajorSolarTerm(int newMoon) {
int mst = majorSolarTerm(newMoon);
int nmn = newMoonNear(newMoon + SYNODIC_GAP, true);
int mstt = majorSolarTerm(nmn);
return mst == mstt;
/*
return majorSolarTerm(newMoon) ==
majorSolarTerm(newMoonNear(newMoon + SYNODIC_GAP, true));
*/
}
//------------------------------------------------------------------
// Time to fields
//------------------------------------------------------------------
/**
* Return true if there is a leap month on or after month newMoon1 and
* at or before month newMoon2.
* @param newMoon1 days after January 1, 1970 0:00 astronomical base zone of a
* new moon
* @param newMoon2 days after January 1, 1970 0:00 astronomical base zone of a
* new moon
*/
private boolean isLeapMonthBetween(int newMoon1, int newMoon2) {
// This is only needed to debug the timeOfAngle divergence bug.
// Remove this later. Liu 11/9/00
// DEBUG
if (synodicMonthsBetween(newMoon1, newMoon2) >= 50) {
throw new IllegalArgumentException("isLeapMonthBetween(" + newMoon1 +
", " + newMoon2 +
"): Invalid parameters");
}
return (newMoon2 >= newMoon1) &&
(isLeapMonthBetween(newMoon1, newMoonNear(newMoon2 - SYNODIC_GAP, false)) ||
hasNoMajorSolarTerm(newMoon2));
}
/**
* Override Calendar to compute several fields specific to the Chinese
* calendar system. These are:
*
*
- ERA
*
- YEAR
*
- MONTH
*
- DAY_OF_MONTH
*
- DAY_OF_YEAR
*
- EXTENDED_YEAR
*
* The DAY_OF_WEEK and DOW_LOCAL fields are already set when this
* method is called. The getGregorianXxx() methods return Gregorian
* calendar equivalents for the given Julian day.
*
* Compute the ChineseCalendar-specific field IS_LEAP_MONTH.
* @stable ICU 2.8
*/
protected void handleComputeFields(int julianDay) {
computeChineseFields(julianDay - EPOCH_JULIAN_DAY, // local days
getGregorianYear(), getGregorianMonth(),
true); // set all fields
}
/**
* Compute fields for the Chinese calendar system. This method can
* either set all relevant fields, as required by
* handleComputeFields(), or it can just set the MONTH and
* IS_LEAP_MONTH fields, as required by
* handleComputeMonthStart().
*
*
As a side effect, this method sets {@link #isLeapYear}.
* @param days days after January 1, 1970 0:00 astronomical base zone of the
* date to compute fields for
* @param gyear the Gregorian year of the given date
* @param gmonth the Gregorian month of the given date
* @param setAllFields if true, set the EXTENDED_YEAR, ERA, YEAR,
* DAY_OF_MONTH, and DAY_OF_YEAR fields. In either case set the MONTH
* and IS_LEAP_MONTH fields.
*/
private void computeChineseFields(int days, int gyear, int gmonth,
boolean setAllFields) {
// Find the winter solstices before and after the target date.
// These define the boundaries of this Chinese year, specifically,
// the position of month 11, which always contains the solstice.
// We want solsticeBefore <= date < solsticeAfter.
int solsticeBefore;
int solsticeAfter = winterSolstice(gyear);
if (days < solsticeAfter) {
solsticeBefore = winterSolstice(gyear - 1);
} else {
solsticeBefore = solsticeAfter;
solsticeAfter = winterSolstice(gyear + 1);
}
// Find the start of the month after month 11. This will be either
// the prior month 12 or leap month 11 (very rare). Also find the
// start of the following month 11.
int firstMoon = newMoonNear(solsticeBefore + 1, true);
int lastMoon = newMoonNear(solsticeAfter + 1, false);
int thisMoon = newMoonNear(days + 1, false); // Start of this month
// Note: isLeapYear is a member variable
isLeapYear = synodicMonthsBetween(firstMoon, lastMoon) == 12;
int month = synodicMonthsBetween(firstMoon, thisMoon);
if (isLeapYear && isLeapMonthBetween(firstMoon, thisMoon)) {
month--;
}
if (month < 1) {
month += 12;
}
boolean isLeapMonth = isLeapYear &&
hasNoMajorSolarTerm(thisMoon) &&
!isLeapMonthBetween(firstMoon, newMoonNear(thisMoon - SYNODIC_GAP, false));
internalSet(MONTH, month-1); // Convert from 1-based to 0-based
internalSet(IS_LEAP_MONTH, isLeapMonth?1:0);
if (setAllFields) {
// Extended year and cycle year is based on the epoch year
int extended_year = gyear - epochYear;
int cycle_year = gyear - CHINESE_EPOCH_YEAR;
if (month < 11 ||
gmonth >= JULY) {
extended_year++;
cycle_year++;
}
int dayOfMonth = days - thisMoon + 1;
internalSet(EXTENDED_YEAR, extended_year);
// 0->0,60 1->1,1 60->1,60 61->2,1 etc.
int[] yearOfCycle = new int[1];
int cycle = floorDivide(cycle_year-1, 60, yearOfCycle);
internalSet(ERA, cycle+1);
internalSet(YEAR, yearOfCycle[0]+1);
internalSet(DAY_OF_MONTH, dayOfMonth);
// Days will be before the first new year we compute if this
// date is in month 11, leap 11, 12. There is never a leap 12.
// New year computations are cached so this should be cheap in
// the long run.
int newYear = newYear(gyear);
if (days < newYear) {
newYear = newYear(gyear-1);
}
internalSet(DAY_OF_YEAR, days - newYear + 1);
}
}
//------------------------------------------------------------------
// Fields to time
//------------------------------------------------------------------
/**
* Return the Chinese new year of the given Gregorian year.
* @param gyear a Gregorian year
* @return days after January 1, 1970 0:00 astronomical base zone of the
* Chinese new year of the given year (this will be a new moon)
*/
private int newYear(int gyear) {
long cacheValue = newYearCache.get(gyear);
if (cacheValue == CalendarCache.EMPTY) {
int solsticeBefore= winterSolstice(gyear - 1);
int solsticeAfter = winterSolstice(gyear);
int newMoon1 = newMoonNear(solsticeBefore + 1, true);
int newMoon2 = newMoonNear(newMoon1 + SYNODIC_GAP, true);
int newMoon11 = newMoonNear(solsticeAfter + 1, false);
if (synodicMonthsBetween(newMoon1, newMoon11) == 12 &&
(hasNoMajorSolarTerm(newMoon1) || hasNoMajorSolarTerm(newMoon2))) {
cacheValue = newMoonNear(newMoon2 + SYNODIC_GAP, true);
} else {
cacheValue = newMoon2;
}
newYearCache.put(gyear, cacheValue);
}
return (int) cacheValue;
}
/**
* Return the Julian day number of day before the first day of the
* given month in the given extended year.
*
*
Note: This method reads the IS_LEAP_MONTH field to determine
* whether the given month is a leap month.
* @param eyear the extended year
* @param month the zero-based month. The month is also determined
* by reading the IS_LEAP_MONTH field.
* @return the Julian day number of the day before the first
* day of the given month and year
* @stable ICU 2.8
*/
protected int handleComputeMonthStart(int eyear, int month, boolean useMonth) {
// If the month is out of range, adjust it into range, and
// modify the extended year value accordingly.
if (month < 0 || month > 11) {
int[] rem = new int[1];
eyear += floorDivide(month, 12, rem);
month = rem[0];
}
int gyear = eyear + epochYear - 1; // Gregorian year
int newYear = newYear(gyear);
int newMoon = newMoonNear(newYear + month * 29, true);
int julianDay = newMoon + EPOCH_JULIAN_DAY;
// Save fields for later restoration
int saveMonth = internalGet(MONTH);
int saveIsLeapMonth = internalGet(IS_LEAP_MONTH);
// Ignore IS_LEAP_MONTH field if useMonth is false
int isLeapMonth = useMonth ? saveIsLeapMonth : 0;
computeGregorianFields(julianDay);
// This will modify the MONTH and IS_LEAP_MONTH fields (only)
computeChineseFields(newMoon, getGregorianYear(),
getGregorianMonth(), false);
if (month != internalGet(MONTH) ||
isLeapMonth != internalGet(IS_LEAP_MONTH)) {
newMoon = newMoonNear(newMoon + SYNODIC_GAP, true);
julianDay = newMoon + EPOCH_JULIAN_DAY;
}
internalSet(MONTH, saveMonth);
internalSet(IS_LEAP_MONTH, saveIsLeapMonth);
return julianDay - 1;
}
/**
* {@inheritDoc}
* @stable ICU 3.8
*/
public String getType() {
return "chinese";
}
/**
* {@inheritDoc}
* @internal
* @deprecated This API is ICU internal only.
*/
@Deprecated
public boolean haveDefaultCentury() {
return false;
}
/**
* Override readObject.
*/
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException
{
epochYear = CHINESE_EPOCH_YEAR;
zoneAstro = CHINA_ZONE;
stream.defaultReadObject();
/* set up the transient caches... */
astro = new CalendarAstronomer();
winterSolsticeCache = new CalendarCache();
newYearCache = new CalendarCache();
}
/*
private static CalendarFactory factory;
public static CalendarFactory factory() {
if (factory == null) {
factory = new CalendarFactory() {
public Calendar create(TimeZone tz, ULocale loc) {
return new ChineseCalendar(tz, loc);
}
public String factoryName() {
return "Chinese";
}
};
}
return factory;
}
*/
}