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1063 lines (1012 loc) · 44.9 KB
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/*
* Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of JSR-310 nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package java.time.zone;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.Year;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
* The rules defining how the zone offset varies for a single time-zone.
* <p>
* The rules model all the historic and future transitions for a time-zone.
* {@link ZoneOffsetTransition} is used for known transitions, typically historic.
* {@link ZoneOffsetTransitionRule} is used for future transitions that are based
* on the result of an algorithm.
* <p>
* The rules are loaded via {@link ZoneRulesProvider} using a {@link ZoneId}.
* The same rules may be shared internally between multiple zone IDs.
* <p>
* Serializing an instance of {@code ZoneRules} will store the entire set of rules.
* It does not store the zone ID as it is not part of the state of this object.
* <p>
* A rule implementation may or may not store full information about historic
* and future transitions, and the information stored is only as accurate as
* that supplied to the implementation by the rules provider.
* Applications should treat the data provided as representing the best information
* available to the implementation of this rule.
*
* @implSpec
* This class is immutable and thread-safe.
*
* @since 1.8
*/
public final class ZoneRules implements Serializable {
/**
* Serialization version.
*/
private static final long serialVersionUID = 3044319355680032515L;
/**
* The last year to have its transitions cached.
*/
private static final int LAST_CACHED_YEAR = 2100;
/**
* The transitions between standard offsets (epoch seconds), sorted.
*/
private final long[] standardTransitions;
/**
* The standard offsets.
*/
private final ZoneOffset[] standardOffsets;
/**
* The transitions between instants (epoch seconds), sorted.
*/
private final long[] savingsInstantTransitions;
/**
* The transitions between local date-times, sorted.
* This is a paired array, where the first entry is the start of the transition
* and the second entry is the end of the transition.
*/
private final LocalDateTime[] savingsLocalTransitions;
/**
* The wall offsets.
*/
private final ZoneOffset[] wallOffsets;
/**
* The last rule.
*/
private final ZoneOffsetTransitionRule[] lastRules;
/**
* The map of recent transitions.
*/
private final transient ConcurrentMap<Integer, ZoneOffsetTransition[]> lastRulesCache =
new ConcurrentHashMap<Integer, ZoneOffsetTransition[]>();
/**
* The zero-length long array.
*/
private static final long[] EMPTY_LONG_ARRAY = new long[0];
/**
* The zero-length lastrules array.
*/
private static final ZoneOffsetTransitionRule[] EMPTY_LASTRULES =
new ZoneOffsetTransitionRule[0];
/**
* The zero-length ldt array.
*/
private static final LocalDateTime[] EMPTY_LDT_ARRAY = new LocalDateTime[0];
/**
* The number of days in a 400 year cycle.
*/
private static final int DAYS_PER_CYCLE = 146097;
/**
* The number of days from year zero to year 1970.
* There are five 400 year cycles from year zero to 2000.
* There are 7 leap years from 1970 to 2000.
*/
private static final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
/**
* Obtains an instance of a ZoneRules.
*
* @param baseStandardOffset the standard offset to use before legal rules were set, not null
* @param baseWallOffset the wall offset to use before legal rules were set, not null
* @param standardOffsetTransitionList the list of changes to the standard offset, not null
* @param transitionList the list of transitions, not null
* @param lastRules the recurring last rules, size 16 or less, not null
* @return the zone rules, not null
*/
public static ZoneRules of(ZoneOffset baseStandardOffset,
ZoneOffset baseWallOffset,
List<ZoneOffsetTransition> standardOffsetTransitionList,
List<ZoneOffsetTransition> transitionList,
List<ZoneOffsetTransitionRule> lastRules) {
Objects.requireNonNull(baseStandardOffset, "baseStandardOffset");
Objects.requireNonNull(baseWallOffset, "baseWallOffset");
Objects.requireNonNull(standardOffsetTransitionList, "standardOffsetTransitionList");
Objects.requireNonNull(transitionList, "transitionList");
Objects.requireNonNull(lastRules, "lastRules");
return new ZoneRules(baseStandardOffset, baseWallOffset,
standardOffsetTransitionList, transitionList, lastRules);
}
/**
* Obtains an instance of ZoneRules that has fixed zone rules.
*
* @param offset the offset this fixed zone rules is based on, not null
* @return the zone rules, not null
* @see #isFixedOffset()
*/
public static ZoneRules of(ZoneOffset offset) {
Objects.requireNonNull(offset, "offset");
return new ZoneRules(offset);
}
/**
* Creates an instance.
*
* @param baseStandardOffset the standard offset to use before legal rules were set, not null
* @param baseWallOffset the wall offset to use before legal rules were set, not null
* @param standardOffsetTransitionList the list of changes to the standard offset, not null
* @param transitionList the list of transitions, not null
* @param lastRules the recurring last rules, size 16 or less, not null
*/
ZoneRules(ZoneOffset baseStandardOffset,
ZoneOffset baseWallOffset,
List<ZoneOffsetTransition> standardOffsetTransitionList,
List<ZoneOffsetTransition> transitionList,
List<ZoneOffsetTransitionRule> lastRules) {
super();
// convert standard transitions
this.standardTransitions = new long[standardOffsetTransitionList.size()];
this.standardOffsets = new ZoneOffset[standardOffsetTransitionList.size() + 1];
this.standardOffsets[0] = baseStandardOffset;
for (int i = 0; i < standardOffsetTransitionList.size(); i++) {
this.standardTransitions[i] = standardOffsetTransitionList.get(i).toEpochSecond();
this.standardOffsets[i + 1] = standardOffsetTransitionList.get(i).getOffsetAfter();
}
// convert savings transitions to locals
List<LocalDateTime> localTransitionList = new ArrayList<>();
List<ZoneOffset> localTransitionOffsetList = new ArrayList<>();
localTransitionOffsetList.add(baseWallOffset);
for (ZoneOffsetTransition trans : transitionList) {
if (trans.isGap()) {
localTransitionList.add(trans.getDateTimeBefore());
localTransitionList.add(trans.getDateTimeAfter());
} else {
localTransitionList.add(trans.getDateTimeAfter());
localTransitionList.add(trans.getDateTimeBefore());
}
localTransitionOffsetList.add(trans.getOffsetAfter());
}
this.savingsLocalTransitions = localTransitionList.toArray(new LocalDateTime[localTransitionList.size()]);
this.wallOffsets = localTransitionOffsetList.toArray(new ZoneOffset[localTransitionOffsetList.size()]);
// convert savings transitions to instants
this.savingsInstantTransitions = new long[transitionList.size()];
for (int i = 0; i < transitionList.size(); i++) {
this.savingsInstantTransitions[i] = transitionList.get(i).toEpochSecond();
}
// last rules
if (lastRules.size() > 16) {
throw new IllegalArgumentException("Too many transition rules");
}
this.lastRules = lastRules.toArray(new ZoneOffsetTransitionRule[lastRules.size()]);
}
/**
* Constructor.
*
* @param standardTransitions the standard transitions, not null
* @param standardOffsets the standard offsets, not null
* @param savingsInstantTransitions the standard transitions, not null
* @param wallOffsets the wall offsets, not null
* @param lastRules the recurring last rules, size 15 or less, not null
*/
private ZoneRules(long[] standardTransitions,
ZoneOffset[] standardOffsets,
long[] savingsInstantTransitions,
ZoneOffset[] wallOffsets,
ZoneOffsetTransitionRule[] lastRules) {
super();
this.standardTransitions = standardTransitions;
this.standardOffsets = standardOffsets;
this.savingsInstantTransitions = savingsInstantTransitions;
this.wallOffsets = wallOffsets;
this.lastRules = lastRules;
if (savingsInstantTransitions.length == 0) {
this.savingsLocalTransitions = EMPTY_LDT_ARRAY;
} else {
// convert savings transitions to locals
List<LocalDateTime> localTransitionList = new ArrayList<>();
for (int i = 0; i < savingsInstantTransitions.length; i++) {
ZoneOffset before = wallOffsets[i];
ZoneOffset after = wallOffsets[i + 1];
ZoneOffsetTransition trans = new ZoneOffsetTransition(savingsInstantTransitions[i], before, after);
if (trans.isGap()) {
localTransitionList.add(trans.getDateTimeBefore());
localTransitionList.add(trans.getDateTimeAfter());
} else {
localTransitionList.add(trans.getDateTimeAfter());
localTransitionList.add(trans.getDateTimeBefore());
}
}
this.savingsLocalTransitions = localTransitionList.toArray(new LocalDateTime[localTransitionList.size()]);
}
}
/**
* Creates an instance of ZoneRules that has fixed zone rules.
*
* @param offset the offset this fixed zone rules is based on, not null
* @see #isFixedOffset()
*/
private ZoneRules(ZoneOffset offset) {
this.standardOffsets = new ZoneOffset[1];
this.standardOffsets[0] = offset;
this.standardTransitions = EMPTY_LONG_ARRAY;
this.savingsInstantTransitions = EMPTY_LONG_ARRAY;
this.savingsLocalTransitions = EMPTY_LDT_ARRAY;
this.wallOffsets = standardOffsets;
this.lastRules = EMPTY_LASTRULES;
}
/**
* Defend against malicious streams.
*
* @param s the stream to read
* @throws InvalidObjectException always
*/
private void readObject(ObjectInputStream s) throws InvalidObjectException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
/**
* Writes the object using a
* <a href="{@docRoot}/serialized-form.html#java.time.zone.Ser">dedicated serialized form</a>.
* @serialData
* <pre style="font-size:1.0em">{@code
*
* out.writeByte(1); // identifies a ZoneRules
* out.writeInt(standardTransitions.length);
* for (long trans : standardTransitions) {
* Ser.writeEpochSec(trans, out);
* }
* for (ZoneOffset offset : standardOffsets) {
* Ser.writeOffset(offset, out);
* }
* out.writeInt(savingsInstantTransitions.length);
* for (long trans : savingsInstantTransitions) {
* Ser.writeEpochSec(trans, out);
* }
* for (ZoneOffset offset : wallOffsets) {
* Ser.writeOffset(offset, out);
* }
* out.writeByte(lastRules.length);
* for (ZoneOffsetTransitionRule rule : lastRules) {
* rule.writeExternal(out);
* }
* }
* </pre>
* <p>
* Epoch second values used for offsets are encoded in a variable
* length form to make the common cases put fewer bytes in the stream.
* <pre style="font-size:1.0em">{@code
*
* static void writeEpochSec(long epochSec, DataOutput out) throws IOException {
* if (epochSec >= -4575744000L && epochSec < 10413792000L && epochSec % 900 == 0) { // quarter hours between 1825 and 2300
* int store = (int) ((epochSec + 4575744000L) / 900);
* out.writeByte((store >>> 16) & 255);
* out.writeByte((store >>> 8) & 255);
* out.writeByte(store & 255);
* } else {
* out.writeByte(255);
* out.writeLong(epochSec);
* }
* }
* }
* </pre>
* <p>
* ZoneOffset values are encoded in a variable length form so the
* common cases put fewer bytes in the stream.
* <pre style="font-size:1.0em">{@code
*
* static void writeOffset(ZoneOffset offset, DataOutput out) throws IOException {
* final int offsetSecs = offset.getTotalSeconds();
* int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127; // compress to -72 to +72
* out.writeByte(offsetByte);
* if (offsetByte == 127) {
* out.writeInt(offsetSecs);
* }
* }
*}
* </pre>
* @return the replacing object, not null
*/
private Object writeReplace() {
return new Ser(Ser.ZRULES, this);
}
/**
* Writes the state to the stream.
*
* @param out the output stream, not null
* @throws IOException if an error occurs
*/
void writeExternal(DataOutput out) throws IOException {
out.writeInt(standardTransitions.length);
for (long trans : standardTransitions) {
Ser.writeEpochSec(trans, out);
}
for (ZoneOffset offset : standardOffsets) {
Ser.writeOffset(offset, out);
}
out.writeInt(savingsInstantTransitions.length);
for (long trans : savingsInstantTransitions) {
Ser.writeEpochSec(trans, out);
}
for (ZoneOffset offset : wallOffsets) {
Ser.writeOffset(offset, out);
}
out.writeByte(lastRules.length);
for (ZoneOffsetTransitionRule rule : lastRules) {
rule.writeExternal(out);
}
}
/**
* Reads the state from the stream.
*
* @param in the input stream, not null
* @return the created object, not null
* @throws IOException if an error occurs
*/
static ZoneRules readExternal(DataInput in) throws IOException, ClassNotFoundException {
int stdSize = in.readInt();
long[] stdTrans = (stdSize == 0) ? EMPTY_LONG_ARRAY
: new long[stdSize];
for (int i = 0; i < stdSize; i++) {
stdTrans[i] = Ser.readEpochSec(in);
}
ZoneOffset[] stdOffsets = new ZoneOffset[stdSize + 1];
for (int i = 0; i < stdOffsets.length; i++) {
stdOffsets[i] = Ser.readOffset(in);
}
int savSize = in.readInt();
long[] savTrans = (savSize == 0) ? EMPTY_LONG_ARRAY
: new long[savSize];
for (int i = 0; i < savSize; i++) {
savTrans[i] = Ser.readEpochSec(in);
}
ZoneOffset[] savOffsets = new ZoneOffset[savSize + 1];
for (int i = 0; i < savOffsets.length; i++) {
savOffsets[i] = Ser.readOffset(in);
}
int ruleSize = in.readByte();
ZoneOffsetTransitionRule[] rules = (ruleSize == 0) ?
EMPTY_LASTRULES : new ZoneOffsetTransitionRule[ruleSize];
for (int i = 0; i < ruleSize; i++) {
rules[i] = ZoneOffsetTransitionRule.readExternal(in);
}
return new ZoneRules(stdTrans, stdOffsets, savTrans, savOffsets, rules);
}
/**
* Checks of the zone rules are fixed, such that the offset never varies.
*
* @return true if the time-zone is fixed and the offset never changes
*/
public boolean isFixedOffset() {
return standardOffsets[0].equals(wallOffsets[0]) &&
standardTransitions.length == 0 &&
savingsInstantTransitions.length == 0 &&
lastRules.length == 0;
}
/**
* Gets the offset applicable at the specified instant in these rules.
* <p>
* The mapping from an instant to an offset is simple, there is only
* one valid offset for each instant.
* This method returns that offset.
*
* @param instant the instant to find the offset for, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the offset, not null
*/
public ZoneOffset getOffset(Instant instant) {
if (savingsInstantTransitions.length == 0) {
return wallOffsets[0];
}
long epochSec = instant.getEpochSecond();
// check if using last rules
if (lastRules.length > 0 &&
epochSec > savingsInstantTransitions[savingsInstantTransitions.length - 1]) {
int year = findYear(epochSec, wallOffsets[wallOffsets.length - 1]);
ZoneOffsetTransition[] transArray = findTransitionArray(year);
ZoneOffsetTransition trans = null;
for (int i = 0; i < transArray.length; i++) {
trans = transArray[i];
if (epochSec < trans.toEpochSecond()) {
return trans.getOffsetBefore();
}
}
return trans.getOffsetAfter();
}
// using historic rules
int index = Arrays.binarySearch(savingsInstantTransitions, epochSec);
if (index < 0) {
// switch negative insert position to start of matched range
index = -index - 2;
}
return wallOffsets[index + 1];
}
/**
* Gets a suitable offset for the specified local date-time in these rules.
* <p>
* The mapping from a local date-time to an offset is not straightforward.
* There are three cases:
* <ul>
* <li>Normal, with one valid offset. For the vast majority of the year, the normal
* case applies, where there is a single valid offset for the local date-time.</li>
* <li>Gap, with zero valid offsets. This is when clocks jump forward typically
* due to the spring daylight savings change from "winter" to "summer".
* In a gap there are local date-time values with no valid offset.</li>
* <li>Overlap, with two valid offsets. This is when clocks are set back typically
* due to the autumn daylight savings change from "summer" to "winter".
* In an overlap there are local date-time values with two valid offsets.</li>
* </ul>
* Thus, for any given local date-time there can be zero, one or two valid offsets.
* This method returns the single offset in the Normal case, and in the Gap or Overlap
* case it returns the offset before the transition.
* <p>
* Since, in the case of Gap and Overlap, the offset returned is a "best" value, rather
* than the "correct" value, it should be treated with care. Applications that care
* about the correct offset should use a combination of this method,
* {@link #getValidOffsets(LocalDateTime)} and {@link #getTransition(LocalDateTime)}.
*
* @param localDateTime the local date-time to query, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the best available offset for the local date-time, not null
*/
public ZoneOffset getOffset(LocalDateTime localDateTime) {
Object info = getOffsetInfo(localDateTime);
if (info instanceof ZoneOffsetTransition) {
return ((ZoneOffsetTransition) info).getOffsetBefore();
}
return (ZoneOffset) info;
}
/**
* Gets the offset applicable at the specified local date-time in these rules.
* <p>
* The mapping from a local date-time to an offset is not straightforward.
* There are three cases:
* <ul>
* <li>Normal, with one valid offset. For the vast majority of the year, the normal
* case applies, where there is a single valid offset for the local date-time.</li>
* <li>Gap, with zero valid offsets. This is when clocks jump forward typically
* due to the spring daylight savings change from "winter" to "summer".
* In a gap there are local date-time values with no valid offset.</li>
* <li>Overlap, with two valid offsets. This is when clocks are set back typically
* due to the autumn daylight savings change from "summer" to "winter".
* In an overlap there are local date-time values with two valid offsets.</li>
* </ul>
* Thus, for any given local date-time there can be zero, one or two valid offsets.
* This method returns that list of valid offsets, which is a list of size 0, 1 or 2.
* In the case where there are two offsets, the earlier offset is returned at index 0
* and the later offset at index 1.
* <p>
* There are various ways to handle the conversion from a {@code LocalDateTime}.
* One technique, using this method, would be:
* <pre>
* List<ZoneOffset> validOffsets = rules.getValidOffsets(localDT);
* if (validOffsets.size() == 1) {
* // Normal case: only one valid offset
* zoneOffset = validOffsets.get(0);
* } else {
* // Gap or Overlap: determine what to do from transition (which will be non-null)
* ZoneOffsetTransition trans = rules.getTransition(localDT);
* }
* </pre>
* <p>
* In theory, it is possible for there to be more than two valid offsets.
* This would happen if clocks to be put back more than once in quick succession.
* This has never happened in the history of time-zones and thus has no special handling.
* However, if it were to happen, then the list would return more than 2 entries.
*
* @param localDateTime the local date-time to query for valid offsets, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the list of valid offsets, may be immutable, not null
*/
public List<ZoneOffset> getValidOffsets(LocalDateTime localDateTime) {
// should probably be optimized
Object info = getOffsetInfo(localDateTime);
if (info instanceof ZoneOffsetTransition) {
return ((ZoneOffsetTransition) info).getValidOffsets();
}
return Collections.singletonList((ZoneOffset) info);
}
/**
* Gets the offset transition applicable at the specified local date-time in these rules.
* <p>
* The mapping from a local date-time to an offset is not straightforward.
* There are three cases:
* <ul>
* <li>Normal, with one valid offset. For the vast majority of the year, the normal
* case applies, where there is a single valid offset for the local date-time.</li>
* <li>Gap, with zero valid offsets. This is when clocks jump forward typically
* due to the spring daylight savings change from "winter" to "summer".
* In a gap there are local date-time values with no valid offset.</li>
* <li>Overlap, with two valid offsets. This is when clocks are set back typically
* due to the autumn daylight savings change from "summer" to "winter".
* In an overlap there are local date-time values with two valid offsets.</li>
* </ul>
* A transition is used to model the cases of a Gap or Overlap.
* The Normal case will return null.
* <p>
* There are various ways to handle the conversion from a {@code LocalDateTime}.
* One technique, using this method, would be:
* <pre>
* ZoneOffsetTransition trans = rules.getTransition(localDT);
* if (trans != null) {
* // Gap or Overlap: determine what to do from transition
* } else {
* // Normal case: only one valid offset
* zoneOffset = rule.getOffset(localDT);
* }
* </pre>
*
* @param localDateTime the local date-time to query for offset transition, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the offset transition, null if the local date-time is not in transition
*/
public ZoneOffsetTransition getTransition(LocalDateTime localDateTime) {
Object info = getOffsetInfo(localDateTime);
return (info instanceof ZoneOffsetTransition ? (ZoneOffsetTransition) info : null);
}
private Object getOffsetInfo(LocalDateTime dt) {
if (savingsLocalTransitions.length == 0) {
return wallOffsets[0];
}
// check if using last rules
if (lastRules.length > 0 &&
dt.isAfter(savingsLocalTransitions[savingsLocalTransitions.length - 1])) {
ZoneOffsetTransition[] transArray = findTransitionArray(dt.getYear());
Object info = null;
for (ZoneOffsetTransition trans : transArray) {
info = findOffsetInfo(dt, trans);
if (info instanceof ZoneOffsetTransition || info.equals(trans.getOffsetBefore())) {
return info;
}
}
return info;
}
// using historic rules
int index = Arrays.binarySearch(savingsLocalTransitions, dt);
if (index == -1) {
// before first transition
return wallOffsets[0];
}
if (index < 0) {
// switch negative insert position to start of matched range
index = -index - 2;
} else if (index < savingsLocalTransitions.length - 1 &&
savingsLocalTransitions[index].equals(savingsLocalTransitions[index + 1])) {
// handle overlap immediately following gap
index++;
}
if ((index & 1) == 0) {
// gap or overlap
LocalDateTime dtBefore = savingsLocalTransitions[index];
LocalDateTime dtAfter = savingsLocalTransitions[index + 1];
ZoneOffset offsetBefore = wallOffsets[index / 2];
ZoneOffset offsetAfter = wallOffsets[index / 2 + 1];
if (offsetAfter.getTotalSeconds() > offsetBefore.getTotalSeconds()) {
// gap
return new ZoneOffsetTransition(dtBefore, offsetBefore, offsetAfter);
} else {
// overlap
return new ZoneOffsetTransition(dtAfter, offsetBefore, offsetAfter);
}
} else {
// normal (neither gap or overlap)
return wallOffsets[index / 2 + 1];
}
}
/**
* Finds the offset info for a local date-time and transition.
*
* @param dt the date-time, not null
* @param trans the transition, not null
* @return the offset info, not null
*/
private Object findOffsetInfo(LocalDateTime dt, ZoneOffsetTransition trans) {
LocalDateTime localTransition = trans.getDateTimeBefore();
if (trans.isGap()) {
if (dt.isBefore(localTransition)) {
return trans.getOffsetBefore();
}
if (dt.isBefore(trans.getDateTimeAfter())) {
return trans;
} else {
return trans.getOffsetAfter();
}
} else {
if (dt.isBefore(localTransition) == false) {
return trans.getOffsetAfter();
}
if (dt.isBefore(trans.getDateTimeAfter())) {
return trans.getOffsetBefore();
} else {
return trans;
}
}
}
/**
* Finds the appropriate transition array for the given year.
*
* @param year the year, not null
* @return the transition array, not null
*/
private ZoneOffsetTransition[] findTransitionArray(int year) {
Integer yearObj = year; // should use Year class, but this saves a class load
ZoneOffsetTransition[] transArray = lastRulesCache.get(yearObj);
if (transArray != null) {
return transArray;
}
ZoneOffsetTransitionRule[] ruleArray = lastRules;
transArray = new ZoneOffsetTransition[ruleArray.length];
for (int i = 0; i < ruleArray.length; i++) {
transArray[i] = ruleArray[i].createTransition(year);
}
if (year < LAST_CACHED_YEAR) {
lastRulesCache.putIfAbsent(yearObj, transArray);
}
return transArray;
}
/**
* Gets the standard offset for the specified instant in this zone.
* <p>
* This provides access to historic information on how the standard offset
* has changed over time.
* The standard offset is the offset before any daylight saving time is applied.
* This is typically the offset applicable during winter.
*
* @param instant the instant to find the offset information for, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the standard offset, not null
*/
public ZoneOffset getStandardOffset(Instant instant) {
if (standardTransitions.length == 0) {
return standardOffsets[0];
}
long epochSec = instant.getEpochSecond();
int index = Arrays.binarySearch(standardTransitions, epochSec);
if (index < 0) {
// switch negative insert position to start of matched range
index = -index - 2;
}
return standardOffsets[index + 1];
}
/**
* Gets the amount of daylight savings in use for the specified instant in this zone.
* <p>
* This provides access to historic information on how the amount of daylight
* savings has changed over time.
* This is the difference between the standard offset and the actual offset.
* Typically the amount is zero during winter and one hour during summer.
* Time-zones are second-based, so the nanosecond part of the duration will be zero.
* <p>
* This default implementation calculates the duration from the
* {@link #getOffset(java.time.Instant) actual} and
* {@link #getStandardOffset(java.time.Instant) standard} offsets.
*
* @param instant the instant to find the daylight savings for, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the difference between the standard and actual offset, not null
*/
public Duration getDaylightSavings(Instant instant) {
if (isFixedOffset()) {
return Duration.ZERO;
}
ZoneOffset standardOffset = getStandardOffset(instant);
ZoneOffset actualOffset = getOffset(instant);
return Duration.ofSeconds(actualOffset.getTotalSeconds() - standardOffset.getTotalSeconds());
}
/**
* Checks if the specified instant is in daylight savings.
* <p>
* This checks if the standard offset and the actual offset are the same
* for the specified instant.
* If they are not, it is assumed that daylight savings is in operation.
* <p>
* This default implementation compares the {@link #getOffset(java.time.Instant) actual}
* and {@link #getStandardOffset(java.time.Instant) standard} offsets.
*
* @param instant the instant to find the offset information for, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the standard offset, not null
*/
public boolean isDaylightSavings(Instant instant) {
return (getStandardOffset(instant).equals(getOffset(instant)) == false);
}
/**
* Checks if the offset date-time is valid for these rules.
* <p>
* To be valid, the local date-time must not be in a gap and the offset
* must match one of the valid offsets.
* <p>
* This default implementation checks if {@link #getValidOffsets(java.time.LocalDateTime)}
* contains the specified offset.
*
* @param localDateTime the date-time to check, not null, but null
* may be ignored if the rules have a single offset for all instants
* @param offset the offset to check, null returns false
* @return true if the offset date-time is valid for these rules
*/
public boolean isValidOffset(LocalDateTime localDateTime, ZoneOffset offset) {
return getValidOffsets(localDateTime).contains(offset);
}
/**
* Gets the next transition after the specified instant.
* <p>
* This returns details of the next transition after the specified instant.
* For example, if the instant represents a point where "Summer" daylight savings time
* applies, then the method will return the transition to the next "Winter" time.
*
* @param instant the instant to get the next transition after, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the next transition after the specified instant, null if this is after the last transition
*/
public ZoneOffsetTransition nextTransition(Instant instant) {
if (savingsInstantTransitions.length == 0) {
return null;
}
long epochSec = instant.getEpochSecond();
// check if using last rules
if (epochSec >= savingsInstantTransitions[savingsInstantTransitions.length - 1]) {
if (lastRules.length == 0) {
return null;
}
// search year the instant is in
int year = findYear(epochSec, wallOffsets[wallOffsets.length - 1]);
ZoneOffsetTransition[] transArray = findTransitionArray(year);
for (ZoneOffsetTransition trans : transArray) {
if (epochSec < trans.toEpochSecond()) {
return trans;
}
}
// use first from following year
if (year < Year.MAX_VALUE) {
transArray = findTransitionArray(year + 1);
return transArray[0];
}
return null;
}
// using historic rules
int index = Arrays.binarySearch(savingsInstantTransitions, epochSec);
if (index < 0) {
index = -index - 1; // switched value is the next transition
} else {
index += 1; // exact match, so need to add one to get the next
}
return new ZoneOffsetTransition(savingsInstantTransitions[index], wallOffsets[index], wallOffsets[index + 1]);
}
/**
* Gets the previous transition before the specified instant.
* <p>
* This returns details of the previous transition before the specified instant.
* For example, if the instant represents a point where "summer" daylight saving time
* applies, then the method will return the transition from the previous "winter" time.
*
* @param instant the instant to get the previous transition after, not null, but null
* may be ignored if the rules have a single offset for all instants
* @return the previous transition before the specified instant, null if this is before the first transition
*/
public ZoneOffsetTransition previousTransition(Instant instant) {
if (savingsInstantTransitions.length == 0) {
return null;
}
long epochSec = instant.getEpochSecond();
if (instant.getNano() > 0 && epochSec < Long.MAX_VALUE) {
epochSec += 1; // allow rest of method to only use seconds
}
// check if using last rules
long lastHistoric = savingsInstantTransitions[savingsInstantTransitions.length - 1];
if (lastRules.length > 0 && epochSec > lastHistoric) {
// search year the instant is in
ZoneOffset lastHistoricOffset = wallOffsets[wallOffsets.length - 1];
int year = findYear(epochSec, lastHistoricOffset);
ZoneOffsetTransition[] transArray = findTransitionArray(year);
for (int i = transArray.length - 1; i >= 0; i--) {
if (epochSec > transArray[i].toEpochSecond()) {
return transArray[i];
}
}
// use last from preceding year
int lastHistoricYear = findYear(lastHistoric, lastHistoricOffset);
if (--year > lastHistoricYear) {
transArray = findTransitionArray(year);
return transArray[transArray.length - 1];
}
// drop through
}
// using historic rules
int index = Arrays.binarySearch(savingsInstantTransitions, epochSec);
if (index < 0) {
index = -index - 1;
}
if (index <= 0) {
return null;
}
return new ZoneOffsetTransition(savingsInstantTransitions[index - 1], wallOffsets[index - 1], wallOffsets[index]);
}
private int findYear(long epochSecond, ZoneOffset offset) {
long localSecond = epochSecond + offset.getTotalSeconds();
long zeroDay = Math.floorDiv(localSecond, 86400) + DAYS_0000_TO_1970;
// find the march-based year
zeroDay -= 60; // adjust to 0000-03-01 so leap day is at end of four year cycle
long adjust = 0;
if (zeroDay < 0) {
// adjust negative years to positive for calculation
long adjustCycles = (zeroDay + 1) / DAYS_PER_CYCLE - 1;
adjust = adjustCycles * 400;
zeroDay += -adjustCycles * DAYS_PER_CYCLE;
}
long yearEst = (400 * zeroDay + 591) / DAYS_PER_CYCLE;
long doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
if (doyEst < 0) {
// fix estimate
yearEst--;
doyEst = zeroDay - (365 * yearEst + yearEst / 4 - yearEst / 100 + yearEst / 400);
}
yearEst += adjust; // reset any negative year
int marchDoy0 = (int) doyEst;
// convert march-based values back to january-based
int marchMonth0 = (marchDoy0 * 5 + 2) / 153;
yearEst += marchMonth0 / 10;
// Cap to the max value
return (int)Math.min(yearEst, Year.MAX_VALUE);
}
/**
* Gets the complete list of fully defined transitions.
* <p>
* The complete set of transitions for this rules instance is defined by this method
* and {@link #getTransitionRules()}. This method returns those transitions that have
* been fully defined. These are typically historical, but may be in the future.
* <p>
* The list will be empty for fixed offset rules and for any time-zone where there has
* only ever been a single offset. The list will also be empty if the transition rules are unknown.
*
* @return an immutable list of fully defined transitions, not null
*/
public List<ZoneOffsetTransition> getTransitions() {
List<ZoneOffsetTransition> list = new ArrayList<>();
for (int i = 0; i < savingsInstantTransitions.length; i++) {
list.add(new ZoneOffsetTransition(savingsInstantTransitions[i], wallOffsets[i], wallOffsets[i + 1]));
}
return Collections.unmodifiableList(list);
}
/**
* Gets the list of transition rules for years beyond those defined in the transition list.
* <p>
* The complete set of transitions for this rules instance is defined by this method
* and {@link #getTransitions()}. This method returns instances of {@link ZoneOffsetTransitionRule}
* that define an algorithm for when transitions will occur.
* <p>
* For any given {@code ZoneRules}, this list contains the transition rules for years
* beyond those years that have been fully defined. These rules typically refer to future
* daylight saving time rule changes.
* <p>
* If the zone defines daylight savings into the future, then the list will normally
* be of size two and hold information about entering and exiting daylight savings.
* If the zone does not have daylight savings, or information about future changes
* is uncertain, then the list will be empty.