456 lines
20 KiB
Java
456 lines
20 KiB
Java
/*
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* Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* This file is available under and governed by the GNU General Public
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* License version 2 only, as published by the Free Software Foundation.
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* However, the following notice accompanied the original version of this
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* file:
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*
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* Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* * Neither the name of JSR-310 nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package java.time.zone;
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import java.security.AccessController;
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import java.security.PrivilegedAction;
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import java.time.ZoneId;
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import java.time.ZonedDateTime;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.List;
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import java.util.NavigableMap;
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import java.util.Objects;
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import java.util.ServiceConfigurationError;
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import java.util.ServiceLoader;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ConcurrentMap;
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import java.util.concurrent.CopyOnWriteArrayList;
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import java.util.Collections;
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/**
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* Provider of time-zone rules to the system.
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* <p>
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* This class manages the configuration of time-zone rules.
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* The static methods provide the public API that can be used to manage the providers.
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* The abstract methods provide the SPI that allows rules to be provided.
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* <p>
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* ZoneRulesProvider may be installed in an instance of the Java Platform as
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* extension classes, that is, jar files placed into any of the usual extension
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* directories. Installed providers are loaded using the service-provider loading
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* facility defined by the {@link ServiceLoader} class. A ZoneRulesProvider
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* identifies itself with a provider configuration file named
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* {@code java.time.zone.ZoneRulesProvider} in the resource directory
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* {@code META-INF/services}. The file should contain a line that specifies the
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* fully qualified concrete zonerules-provider class name.
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* Providers may also be made available by adding them to the class path or by
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* registering themselves via {@link #registerProvider} method.
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* <p>
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* The Java virtual machine has a default provider that provides zone rules
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* for the time-zones defined by IANA Time Zone Database (TZDB). If the system
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* property {@systemProperty java.time.zone.DefaultZoneRulesProvider} is defined then
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* it is taken to be the fully-qualified name of a concrete ZoneRulesProvider
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* class to be loaded as the default provider, using the system class loader.
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* If this system property is not defined, a system-default provider will be
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* loaded to serve as the default provider.
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* <p>
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* Rules are looked up primarily by zone ID, as used by {@link ZoneId}.
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* Only zone region IDs may be used, zone offset IDs are not used here.
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* <p>
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* Time-zone rules are political, thus the data can change at any time.
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* Each provider will provide the latest rules for each zone ID, but they
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* may also provide the history of how the rules changed.
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*
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* @implSpec
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* This interface is a service provider that can be called by multiple threads.
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* Implementations must be immutable and thread-safe.
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* <p>
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* Providers must ensure that once a rule has been seen by the application, the
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* rule must continue to be available.
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* <p>
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* Providers are encouraged to implement a meaningful {@code toString} method.
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* <p>
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* Many systems would like to update time-zone rules dynamically without stopping the JVM.
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* When examined in detail, this is a complex problem.
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* Providers may choose to handle dynamic updates, however the default provider does not.
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*
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* @since 1.8
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*/
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@SuppressWarnings("removal")
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public abstract class ZoneRulesProvider {
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/**
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* The set of loaded providers.
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*/
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private static final CopyOnWriteArrayList<ZoneRulesProvider> PROVIDERS = new CopyOnWriteArrayList<>();
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/**
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* The lookup from zone ID to provider.
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*/
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private static final ConcurrentMap<String, ZoneRulesProvider> ZONES = new ConcurrentHashMap<>(512, 0.75f, 2);
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/**
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* The zone ID data
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*/
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private static volatile Set<String> ZONE_IDS;
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static {
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// BEGIN Android-changed: use a single hard-coded provider.
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/*
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// if the property java.time.zone.DefaultZoneRulesProvider is
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// set then its value is the class name of the default provider
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final List<ZoneRulesProvider> loaded = new ArrayList<>();
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AccessController.doPrivileged(new PrivilegedAction<>() {
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public Object run() {
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String prop = System.getProperty("java.time.zone.DefaultZoneRulesProvider");
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if (prop != null) {
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try {
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Class<?> c = Class.forName(prop, true, ClassLoader.getSystemClassLoader());
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@SuppressWarnings("deprecation")
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ZoneRulesProvider provider = ZoneRulesProvider.class.cast(c.newInstance());
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registerProvider(provider);
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loaded.add(provider);
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} catch (Exception x) {
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throw new Error(x);
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}
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} else {
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registerProvider(new TzdbZoneRulesProvider());
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}
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return null;
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}
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});
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ServiceLoader<ZoneRulesProvider> sl = ServiceLoader.load(ZoneRulesProvider.class, ClassLoader.getSystemClassLoader());
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Iterator<ZoneRulesProvider> it = sl.iterator();
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while (it.hasNext()) {
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ZoneRulesProvider provider;
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try {
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provider = it.next();
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} catch (ServiceConfigurationError ex) {
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if (ex.getCause() instanceof SecurityException) {
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continue; // ignore the security exception, try the next provider
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}
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throw ex;
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}
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boolean found = false;
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for (ZoneRulesProvider p : loaded) {
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if (p.getClass() == provider.getClass()) {
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found = true;
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}
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}
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if (!found) {
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registerProvider0(provider);
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loaded.add(provider);
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}
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}
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// CopyOnWriteList could be slow if lots of providers and each added individually
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PROVIDERS.addAll(loaded);
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*/
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ZoneRulesProvider provider = new IcuZoneRulesProvider();
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registerProvider(provider);
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// END Android-changed: use a single hard-coded provider.
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}
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//-------------------------------------------------------------------------
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/**
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* Gets the set of available zone IDs.
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* <p>
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* These IDs are the string form of a {@link ZoneId}.
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*
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* @return the unmodifiable set of zone IDs, not null
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*/
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public static Set<String> getAvailableZoneIds() {
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return ZONE_IDS;
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}
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/**
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* Gets the rules for the zone ID.
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* <p>
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* This returns the latest available rules for the zone ID.
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* <p>
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* This method relies on time-zone data provider files that are configured.
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* These are loaded using a {@code ServiceLoader}.
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* <p>
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* The caching flag is designed to allow provider implementations to
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* prevent the rules being cached in {@code ZoneId}.
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* Under normal circumstances, the caching of zone rules is highly desirable
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* as it will provide greater performance. However, there is a use case where
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* the caching would not be desirable, see {@link #provideRules}.
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*
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* @param zoneId the zone ID as defined by {@code ZoneId}, not null
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* @param forCaching whether the rules are being queried for caching,
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* true if the returned rules will be cached by {@code ZoneId},
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* false if they will be returned to the user without being cached in {@code ZoneId}
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* @return the rules, null if {@code forCaching} is true and this
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* is a dynamic provider that wants to prevent caching in {@code ZoneId},
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* otherwise not null
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* @throws ZoneRulesException if rules cannot be obtained for the zone ID
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*/
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public static ZoneRules getRules(String zoneId, boolean forCaching) {
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Objects.requireNonNull(zoneId, "zoneId");
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return getProvider(zoneId).provideRules(zoneId, forCaching);
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}
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/**
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* Gets the history of rules for the zone ID.
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* <p>
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* Time-zones are defined by governments and change frequently.
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* This method allows applications to find the history of changes to the
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* rules for a single zone ID. The map is keyed by a string, which is the
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* version string associated with the rules.
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* <p>
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* The exact meaning and format of the version is provider specific.
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* The version must follow lexicographical order, thus the returned map will
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* be order from the oldest known rules to the newest available rules.
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* The default 'TZDB' group uses version numbering consisting of the year
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* followed by a letter, such as '2009e' or '2012f'.
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* <p>
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* Implementations must provide a result for each valid zone ID, however
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* they do not have to provide a history of rules.
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* Thus the map will always contain one element, and will only contain more
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* than one element if historical rule information is available.
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*
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* @param zoneId the zone ID as defined by {@code ZoneId}, not null
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* @return a modifiable copy of the history of the rules for the ID, sorted
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* from oldest to newest, not null
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* @throws ZoneRulesException if history cannot be obtained for the zone ID
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*/
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public static NavigableMap<String, ZoneRules> getVersions(String zoneId) {
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Objects.requireNonNull(zoneId, "zoneId");
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return getProvider(zoneId).provideVersions(zoneId);
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}
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/**
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* Gets the provider for the zone ID.
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*
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* @param zoneId the zone ID as defined by {@code ZoneId}, not null
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* @return the provider, not null
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* @throws ZoneRulesException if the zone ID is unknown
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*/
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private static ZoneRulesProvider getProvider(String zoneId) {
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ZoneRulesProvider provider = ZONES.get(zoneId);
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if (provider == null) {
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if (ZONES.isEmpty()) {
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throw new ZoneRulesException("No time-zone data files registered");
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}
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throw new ZoneRulesException("Unknown time-zone ID: " + zoneId);
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}
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return provider;
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}
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//-------------------------------------------------------------------------
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/**
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* Registers a zone rules provider.
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* <p>
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* This adds a new provider to those currently available.
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* A provider supplies rules for one or more zone IDs.
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* A provider cannot be registered if it supplies a zone ID that has already been
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* registered. See the notes on time-zone IDs in {@link ZoneId}, especially
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* the section on using the concept of a "group" to make IDs unique.
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* <p>
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* To ensure the integrity of time-zones already created, there is no way
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* to deregister providers.
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*
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* @param provider the provider to register, not null
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* @throws ZoneRulesException if a zone ID is already registered
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*/
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public static void registerProvider(ZoneRulesProvider provider) {
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Objects.requireNonNull(provider, "provider");
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registerProvider0(provider);
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PROVIDERS.add(provider);
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}
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/**
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* Registers the provider.
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*
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* @param provider the provider to register, not null
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* @throws ZoneRulesException if unable to complete the registration
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*/
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private static synchronized void registerProvider0(ZoneRulesProvider provider) {
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for (String zoneId : provider.provideZoneIds()) {
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Objects.requireNonNull(zoneId, "zoneId");
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ZoneRulesProvider old = ZONES.putIfAbsent(zoneId, provider);
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if (old != null) {
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throw new ZoneRulesException(
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"Unable to register zone as one already registered with that ID: " + zoneId +
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", currently loading from provider: " + provider);
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}
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}
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Set<String> combinedSet = new HashSet<String>(ZONES.keySet());
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ZONE_IDS = Collections.unmodifiableSet(combinedSet);
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}
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/**
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* Refreshes the rules from the underlying data provider.
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* <p>
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* This method allows an application to request that the providers check
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* for any updates to the provided rules.
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* After calling this method, the offset stored in any {@link ZonedDateTime}
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* may be invalid for the zone ID.
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* <p>
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* Dynamic update of rules is a complex problem and most applications
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* should not use this method or dynamic rules.
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* To achieve dynamic rules, a provider implementation will have to be written
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* as per the specification of this class.
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* In addition, instances of {@code ZoneRules} must not be cached in the
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* application as they will become stale. However, the boolean flag on
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* {@link #provideRules(String, boolean)} allows provider implementations
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* to control the caching of {@code ZoneId}, potentially ensuring that
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* all objects in the system see the new rules.
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* Note that there is likely to be a cost in performance of a dynamic rules
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* provider. Note also that no dynamic rules provider is in this specification.
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*
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* @return true if the rules were updated
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* @throws ZoneRulesException if an error occurs during the refresh
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*/
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public static boolean refresh() {
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boolean changed = false;
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for (ZoneRulesProvider provider : PROVIDERS) {
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changed |= provider.provideRefresh();
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}
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return changed;
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}
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/**
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* Constructor.
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*/
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protected ZoneRulesProvider() {
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}
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//-----------------------------------------------------------------------
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/**
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* SPI method to get the available zone IDs.
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* <p>
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* This obtains the IDs that this {@code ZoneRulesProvider} provides.
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* A provider should provide data for at least one zone ID.
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* <p>
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* The returned zone IDs remain available and valid for the lifetime of the application.
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* A dynamic provider may increase the set of IDs as more data becomes available.
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*
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* @return the set of zone IDs being provided, not null
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* @throws ZoneRulesException if a problem occurs while providing the IDs
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*/
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protected abstract Set<String> provideZoneIds();
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/**
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* SPI method to get the rules for the zone ID.
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* <p>
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* This loads the rules for the specified zone ID.
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* The provider implementation must validate that the zone ID is valid and
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* available, throwing a {@code ZoneRulesException} if it is not.
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* The result of the method in the valid case depends on the caching flag.
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* <p>
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* If the provider implementation is not dynamic, then the result of the
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* method must be the non-null set of rules selected by the ID.
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* <p>
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* If the provider implementation is dynamic, then the flag gives the option
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* of preventing the returned rules from being cached in {@link ZoneId}.
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* When the flag is true, the provider is permitted to return null, where
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* null will prevent the rules from being cached in {@code ZoneId}.
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* When the flag is false, the provider must return non-null rules.
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*
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* @param zoneId the zone ID as defined by {@code ZoneId}, not null
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* @param forCaching whether the rules are being queried for caching,
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* true if the returned rules will be cached by {@code ZoneId},
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* false if they will be returned to the user without being cached in {@code ZoneId}
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* @return the rules, null if {@code forCaching} is true and this
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* is a dynamic provider that wants to prevent caching in {@code ZoneId},
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* otherwise not null
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* @throws ZoneRulesException if rules cannot be obtained for the zone ID
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*/
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protected abstract ZoneRules provideRules(String zoneId, boolean forCaching);
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/**
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* SPI method to get the history of rules for the zone ID.
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* <p>
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* This returns a map of historical rules keyed by a version string.
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* The exact meaning and format of the version is provider specific.
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* The version must follow lexicographical order, thus the returned map will
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* be order from the oldest known rules to the newest available rules.
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* The default 'TZDB' group uses version numbering consisting of the year
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* followed by a letter, such as '2009e' or '2012f'.
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* <p>
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* Implementations must provide a result for each valid zone ID, however
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* they do not have to provide a history of rules.
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* Thus the map will contain at least one element, and will only contain
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* more than one element if historical rule information is available.
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* <p>
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* The returned versions remain available and valid for the lifetime of the application.
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* A dynamic provider may increase the set of versions as more data becomes available.
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*
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* @param zoneId the zone ID as defined by {@code ZoneId}, not null
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* @return a modifiable copy of the history of the rules for the ID, sorted
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* from oldest to newest, not null
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* @throws ZoneRulesException if history cannot be obtained for the zone ID
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*/
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protected abstract NavigableMap<String, ZoneRules> provideVersions(String zoneId);
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/**
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* SPI method to refresh the rules from the underlying data provider.
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* <p>
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* This method provides the opportunity for a provider to dynamically
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* recheck the underlying data provider to find the latest rules.
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* This could be used to load new rules without stopping the JVM.
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* Dynamic behavior is entirely optional and most providers do not support it.
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* <p>
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* This implementation returns false.
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*
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* @return true if the rules were updated
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* @throws ZoneRulesException if an error occurs during the refresh
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*/
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protected boolean provideRefresh() {
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return false;
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}
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}
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