ZoneInfo is an implementation subclass of {@link
* java.util.TimeZone TimeZone} that represents GMT offsets and
* daylight saving time transitions of a time zone.
*
* The daylight saving time transitions are described in the {@link
* #transitions transitions} table consisting of a chronological
* sequence of transitions of GMT offset and/or daylight saving time
* changes. Since all transitions are represented in UTC, in theory,
* ZoneInfo can be used with any calendar systems except
* for the {@link #getOffset(int,int,int,int,int,int) getOffset}
* method that takes Gregorian calendar date fields.
*
* This table covers transitions from 1900 until 2037 (as of version
* 1.4), Before 1900, it assumes that there was no daylight saving
* time and the getOffset methods always return the
* {@link #getRawOffset} value. No Local Mean Time is supported. If a
* specified date is beyond the transition table and this time zone is
* supposed to observe daylight saving time in 2037, it delegates
* operations to a {@link java.util.SimpleTimeZone SimpleTimeZone}
* object created using the daylight saving time schedule as of 2037.
*
* The date items, transitions, GMT offset(s), etc. are read from a database
* file. See {@link ZoneInfoFile} for details.
* @see java.util.SimpleTimeZone
* @since 1.4
*/
public class ZoneInfo extends TimeZone {
private static final int UTC_TIME = 0;
private static final int STANDARD_TIME = 1;
private static final int WALL_TIME = 2;
private static final long OFFSET_MASK = 0x0fL;
private static final long DST_MASK = 0xf0L;
private static final int DST_NSHIFT = 4;
// this bit field is reserved for abbreviation support
private static final long ABBR_MASK = 0xf00L;
private static final int TRANSITION_NSHIFT = 12;
private static final CalendarSystem gcal = CalendarSystem.getGregorianCalendar();
/**
* The raw GMT offset in milliseconds between this zone and GMT.
* Negative offsets are to the west of Greenwich. To obtain local
* standard time, add the offset to GMT time.
* @serial
*/
private int rawOffset;
/**
* Difference in milliseconds from the original GMT offset in case
* the raw offset value has been modified by calling {@link
* #setRawOffset}. The initial value is 0.
* @serial
*/
private int rawOffsetDiff = 0;
/**
* A CRC32 value of all pairs of transition time (in milliseconds
* in long) in local time and its GMT offset (in
* seconds in int) in the chronological order. Byte
* values of each long and int are taken
* in the big endian order (i.e., MSB to LSB).
* @serial
*/
private int checksum;
/**
* The amount of time in milliseconds saved during daylight saving
* time. If useDaylight is false, this value is 0.
* @serial
*/
private int dstSavings;
/**
* This array describes transitions of GMT offsets of this time
* zone, including both raw offset changes and daylight saving
* time changes.
* A long integer consists of four bit fields.
*
* Note: In general, clients should use
* {@link Calendar#ZONE_OFFSET Calendar.get(ZONE_OFFSET)} +
* {@link Calendar#DST_OFFSET Calendar.get(DST_OFFSET)}
* instead of calling this method.
*
* @param era The era of the given date. The value must be either
* GregorianCalendar.AD or GregorianCalendar.BC.
* @param year The year in the given date.
* @param month The month in the given date. Month is 0-based. e.g.,
* 0 for January.
* @param day The day-in-month of the given date.
* @param dayOfWeek The day-of-week of the given date.
* @param milliseconds The milliseconds in day in standard local time.
* @return The milliseconds to add to UTC to get local time.
*/
public int getOffset(int era, int year, int month, int day,
int dayOfWeek, int milliseconds) {
if (milliseconds < 0 || milliseconds >= AbstractCalendar.DAY_IN_MILLIS) {
throw new IllegalArgumentException();
}
if (era == java.util.GregorianCalendar.BC) { // BC
year = 1 - year;
} else if (era != java.util.GregorianCalendar.AD) {
throw new IllegalArgumentException();
}
CalendarDate date = gcal.newCalendarDate(null);
date.setDate(year, month + 1, day);
if (gcal.validate(date) == false) {
throw new IllegalArgumentException();
}
// bug-for-bug compatible argument checking
if (dayOfWeek < java.util.GregorianCalendar.SUNDAY
|| dayOfWeek > java.util.GregorianCalendar.SATURDAY) {
throw new IllegalArgumentException();
}
if (transitions == null) {
return getLastRawOffset();
}
long dateInMillis = gcal.getTime(date) + milliseconds;
dateInMillis -= (long) rawOffset; // make it UTC
return getOffsets(dateInMillis, null, UTC_TIME);
}
/**
* Sets the base time zone offset from GMT. This operation
* modifies all the transitions of this ZoneInfo object, including
* historical ones, if applicable.
*
* @param offsetMillis the base time zone offset to GMT.
* @see getRawOffset
*/
public synchronized void setRawOffset(int offsetMillis) {
if (offsetMillis == rawOffset + rawOffsetDiff) {
return;
}
rawOffsetDiff = offsetMillis - rawOffset;
if (lastRule != null) {
lastRule.setRawOffset(offsetMillis);
}
dirty = true;
}
/**
* Returns the GMT offset of the current date. This GMT offset
* value is not modified during Daylight Saving Time.
*
* @return the GMT offset value in milliseconds to add to UTC time
* to get local standard time
*/
public int getRawOffset() {
if (!willGMTOffsetChange) {
return rawOffset + rawOffsetDiff;
}
int[] offsets = new int[2];
getOffsets(System.currentTimeMillis(), offsets, UTC_TIME);
return offsets[0];
}
public boolean isDirty() {
return dirty;
}
private int getLastRawOffset() {
return rawOffset + rawOffsetDiff;
}
/**
* Queries if this time zone uses Daylight Saving Time in the last known rule.
*/
public boolean useDaylightTime() {
return (simpleTimeZoneParams != null);
}
@Override
public boolean observesDaylightTime() {
if (simpleTimeZoneParams != null) {
return true;
}
if (transitions == null) {
return false;
}
// Look up the transition table to see if it's in DST right
// now or if there's any standard-to-daylight transition at
// any future.
long utc = System.currentTimeMillis() - rawOffsetDiff;
int index = getTransitionIndex(utc, UTC_TIME);
// before transitions in the transition table
if (index < 0) {
return false;
}
// the time is in the table range.
for (int i = index; i < transitions.length; i++) {
if ((transitions[i] & DST_MASK) != 0) {
return true;
}
}
// No further DST is observed.
return false;
}
/**
* Queries if the specified date is in Daylight Saving Time.
*/
public boolean inDaylightTime(Date date) {
if (date == null) {
throw new NullPointerException();
}
if (transitions == null) {
return false;
}
long utc = date.getTime() - rawOffsetDiff;
int index = getTransitionIndex(utc, UTC_TIME);
// before transitions in the transition table
if (index < 0) {
return false;
}
// the time is in the table range.
if (index < transitions.length) {
return (transitions[index] & DST_MASK) != 0;
}
// beyond the transition table
SimpleTimeZone tz = getLastRule();
if (tz != null) {
return tz.inDaylightTime(date);
}
return false;
}
/**
* Returns the amount of time in milliseconds that the clock is advanced
* during daylight saving time is in effect in its last daylight saving time rule.
*
* @return the number of milliseconds the time is advanced with respect to
* standard time when daylight saving time is in effect.
*/
public int getDSTSavings() {
return dstSavings;
}
// /**
// * @return the last year in the transition table or -1 if this
// * time zone doesn't observe any daylight saving time.
// */
// public int getMaxTransitionYear() {
// if (transitions == null) {
// return -1;
// }
// long val = transitions[transitions.length - 1];
// int offset = this.offsets[(int)(val & OFFSET_MASK)] + rawOffsetDiff;
// val = (val >> TRANSITION_NSHIFT) + offset;
// CalendarDate lastDate = Gregorian.getCalendarDate(val);
// return lastDate.getYear();
// }
/**
* Returns a string representation of this time zone.
* @return the string
*/
public String toString() {
return getClass().getName() +
"[id=\"" + getID() + "\"" +
",offset=" + getLastRawOffset() +
",dstSavings=" + dstSavings +
",useDaylight=" + useDaylightTime() +
",transitions=" + ((transitions != null) ? transitions.length : 0) +
",lastRule=" + (lastRule == null ? getLastRuleInstance() : lastRule) +
"]";
}
/**
* Gets all available IDs supported in the Java run-time.
*
* @return an array of time zone IDs.
*/
public static String[] getAvailableIDs() {
return ZoneInfoFile.getZoneIds();
}
/**
* Gets all available IDs that have the same value as the
* specified raw GMT offset.
*
* @param rawOffset the GMT offset in milliseconds. This
* value should not include any daylight saving time.
*
* @return an array of time zone IDs.
*/
public static String[] getAvailableIDs(int rawOffset) {
return ZoneInfoFile.getZoneIds(rawOffset);
}
/**
* Gets the ZoneInfo for the given ID.
*
* @param ID the ID for a ZoneInfo. See TimeZone for detail.
*
* @return the specified ZoneInfo object, or null if there is no
* time zone of the ID.
*/
public static TimeZone getTimeZone(String ID) {
return ZoneInfoFile.getZoneInfo(ID);
}
private transient SimpleTimeZone lastRule;
/**
* Returns a SimpleTimeZone object representing the last GMT
* offset and DST schedule or null if this time zone doesn't
* observe DST.
*/
private synchronized SimpleTimeZone getLastRule() {
if (lastRule == null) {
lastRule = getLastRuleInstance();
}
return lastRule;
}
/**
* Returns a SimpleTimeZone object that represents the last
* known daylight saving time rules.
*
* @return a SimpleTimeZone object or null if this time zone
* doesn't observe DST.
*/
public SimpleTimeZone getLastRuleInstance() {
if (simpleTimeZoneParams == null) {
return null;
}
if (simpleTimeZoneParams.length == 10) {
return new SimpleTimeZone(getLastRawOffset(), getID(),
simpleTimeZoneParams[0],
simpleTimeZoneParams[1],
simpleTimeZoneParams[2],
simpleTimeZoneParams[3],
simpleTimeZoneParams[4],
simpleTimeZoneParams[5],
simpleTimeZoneParams[6],
simpleTimeZoneParams[7],
simpleTimeZoneParams[8],
simpleTimeZoneParams[9],
dstSavings);
}
return new SimpleTimeZone(getLastRawOffset(), getID(),
simpleTimeZoneParams[0],
simpleTimeZoneParams[1],
simpleTimeZoneParams[2],
simpleTimeZoneParams[3],
simpleTimeZoneParams[4],
simpleTimeZoneParams[5],
simpleTimeZoneParams[6],
simpleTimeZoneParams[7],
dstSavings);
}
/**
* Returns a copy of this ZoneInfo.
*/
public Object clone() {
ZoneInfo zi = (ZoneInfo) super.clone();
zi.lastRule = null;
return zi;
}
/**
* Returns a hash code value calculated from the GMT offset and
* transitions.
* @return a hash code of this time zone
*/
public int hashCode() {
return getLastRawOffset() ^ checksum;
}
/**
* Compares the equity of two ZoneInfo objects.
*
* @param obj the object to be compared with
* @return true if given object is same as this ZoneInfo object,
* false otherwise.
*/
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof ZoneInfo)) {
return false;
}
ZoneInfo that = (ZoneInfo) obj;
return (getID().equals(that.getID())
&& (getLastRawOffset() == that.getLastRawOffset())
&& (checksum == that.checksum));
}
/**
* Returns true if this zone has the same raw GMT offset value and
* transition table as another zone info. If the specified
* TimeZone object is not a ZoneInfo instance, this method returns
* true if the specified TimeZone object has the same raw GMT
* offset value with no daylight saving time.
*
* @param other the ZoneInfo object to be compared with
* @return true if the given TimeZone has the same
* GMT offset and transition information; false, otherwise.
*/
public boolean hasSameRules(TimeZone other) {
if (this == other) {
return true;
}
if (other == null) {
return false;
}
if (!(other instanceof ZoneInfo)) {
if (getRawOffset() != other.getRawOffset()) {
return false;
}
// if both have the same raw offset and neither observes
// DST, they have the same rule.
if ((transitions == null)
&& (useDaylightTime() == false)
&& (other.useDaylightTime() == false)) {
return true;
}
return false;
}
if (getLastRawOffset() != ((ZoneInfo)other).getLastRawOffset()) {
return false;
}
return (checksum == ((ZoneInfo)other).checksum);
}
/**
* Returns a Map from alias time zone IDs to their standard
* time zone IDs.
*
* @return the Map that holds the mappings from alias time zone IDs
* to their standard time zone IDs, or null if
* ZoneInfoMappings file is not available.
*/
public static Map