1 /* 2 * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* 27 * This file is available under and governed by the GNU General Public 28 * License version 2 only, as published by the Free Software Foundation. 29 * However, the following notice accompanied the original version of this 30 * file: 31 * 32 * Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos 33 * 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions are met: 38 * 39 * * Redistributions of source code must retain the above copyright notice, 40 * this list of conditions and the following disclaimer. 41 * 42 * * Redistributions in binary form must reproduce the above copyright notice, 43 * this list of conditions and the following disclaimer in the documentation 44 * and/or other materials provided with the distribution. 45 * 46 * * Neither the name of JSR-310 nor the names of its contributors 47 * may be used to endorse or promote products derived from this software 48 * without specific prior written permission. 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 61 */ 62 package java.time.zone; 63 64 import java.security.AccessController; 65 import java.security.PrivilegedAction; 66 import java.time.ZoneId; 67 import java.time.ZonedDateTime; 68 import java.util.ArrayList; 69 import java.util.HashSet; 70 import java.util.Iterator; 71 import java.util.List; 72 import java.util.NavigableMap; 73 import java.util.Objects; 74 import java.util.ServiceConfigurationError; 75 import java.util.ServiceLoader; 76 import java.util.Set; 77 import java.util.concurrent.ConcurrentHashMap; 78 import java.util.concurrent.ConcurrentMap; 79 import java.util.concurrent.CopyOnWriteArrayList; 80 import java.util.Collections; 81 82 /** 83 * Provider of time-zone rules to the system. 84 * <p> 85 * This class manages the configuration of time-zone rules. 86 * The static methods provide the public API that can be used to manage the providers. 87 * The abstract methods provide the SPI that allows rules to be provided. 88 * <p> 89 * ZoneRulesProvider may be installed in an instance of the Java Platform as 90 * extension classes, that is, jar files placed into any of the usual extension 91 * directories. Installed providers are loaded using the service-provider loading 92 * facility defined by the {@link ServiceLoader} class. A ZoneRulesProvider 93 * identifies itself with a provider configuration file named 94 * {@code java.time.zone.ZoneRulesProvider} in the resource directory 95 * {@code META-INF/services}. The file should contain a line that specifies the 96 * fully qualified concrete zonerules-provider class name. 97 * Providers may also be made available by adding them to the class path or by 98 * registering themselves via {@link #registerProvider} method. 99 * <p> 100 * The Java virtual machine has a default provider that provides zone rules 101 * for the time-zones defined by IANA Time Zone Database (TZDB). If the system 102 * property {@systemProperty java.time.zone.DefaultZoneRulesProvider} is defined then 103 * it is taken to be the fully-qualified name of a concrete ZoneRulesProvider 104 * class to be loaded as the default provider, using the system class loader. 105 * If this system property is not defined, a system-default provider will be 106 * loaded to serve as the default provider. 107 * <p> 108 * Rules are looked up primarily by zone ID, as used by {@link ZoneId}. 109 * Only zone region IDs may be used, zone offset IDs are not used here. 110 * <p> 111 * Time-zone rules are political, thus the data can change at any time. 112 * Each provider will provide the latest rules for each zone ID, but they 113 * may also provide the history of how the rules changed. 114 * 115 * @implSpec 116 * This interface is a service provider that can be called by multiple threads. 117 * Implementations must be immutable and thread-safe. 118 * <p> 119 * Providers must ensure that once a rule has been seen by the application, the 120 * rule must continue to be available. 121 * <p> 122 * Providers are encouraged to implement a meaningful {@code toString} method. 123 * <p> 124 * Many systems would like to update time-zone rules dynamically without stopping the JVM. 125 * When examined in detail, this is a complex problem. 126 * Providers may choose to handle dynamic updates, however the default provider does not. 127 * 128 * @since 1.8 129 */ 130 @SuppressWarnings("removal") 131 public abstract class ZoneRulesProvider { 132 133 /** 134 * The set of loaded providers. 135 */ 136 private static final CopyOnWriteArrayList<ZoneRulesProvider> PROVIDERS = new CopyOnWriteArrayList<>(); 137 /** 138 * The lookup from zone ID to provider. 139 */ 140 private static final ConcurrentMap<String, ZoneRulesProvider> ZONES = new ConcurrentHashMap<>(512, 0.75f, 2); 141 142 /** 143 * The zone ID data 144 */ 145 private static volatile Set<String> ZONE_IDS; 146 147 static { 148 // BEGIN Android-changed: use a single hard-coded provider. 149 /* 150 // if the property java.time.zone.DefaultZoneRulesProvider is 151 // set then its value is the class name of the default provider 152 final List<ZoneRulesProvider> loaded = new ArrayList<>(); 153 AccessController.doPrivileged(new PrivilegedAction<>() { 154 public Object run() { 155 String prop = System.getProperty("java.time.zone.DefaultZoneRulesProvider"); 156 if (prop != null) { 157 try { 158 Class<?> c = Class.forName(prop, true, ClassLoader.getSystemClassLoader()); 159 @SuppressWarnings("deprecation") 160 ZoneRulesProvider provider = ZoneRulesProvider.class.cast(c.newInstance()); 161 registerProvider(provider); 162 loaded.add(provider); 163 } catch (Exception x) { 164 throw new Error(x); 165 } 166 } else { 167 registerProvider(new TzdbZoneRulesProvider()); 168 } 169 return null; 170 } 171 }); 172 173 ServiceLoader<ZoneRulesProvider> sl = ServiceLoader.load(ZoneRulesProvider.class, ClassLoader.getSystemClassLoader()); 174 Iterator<ZoneRulesProvider> it = sl.iterator(); 175 while (it.hasNext()) { 176 ZoneRulesProvider provider; 177 try { 178 provider = it.next(); 179 } catch (ServiceConfigurationError ex) { 180 if (ex.getCause() instanceof SecurityException) { 181 continue; // ignore the security exception, try the next provider 182 } 183 throw ex; 184 } 185 boolean found = false; 186 for (ZoneRulesProvider p : loaded) { 187 if (p.getClass() == provider.getClass()) { 188 found = true; 189 } 190 } 191 if (!found) { 192 registerProvider0(provider); 193 loaded.add(provider); 194 } 195 } 196 // CopyOnWriteList could be slow if lots of providers and each added individually 197 PROVIDERS.addAll(loaded); 198 */ 199 ZoneRulesProvider provider = new IcuZoneRulesProvider(); 200 registerProvider(provider); 201 // END Android-changed: use a single hard-coded provider. 202 } 203 204 //------------------------------------------------------------------------- 205 /** 206 * Gets the set of available zone IDs. 207 * <p> 208 * These IDs are the string form of a {@link ZoneId}. 209 * 210 * @return the unmodifiable set of zone IDs, not null 211 */ getAvailableZoneIds()212 public static Set<String> getAvailableZoneIds() { 213 return ZONE_IDS; 214 } 215 216 /** 217 * Gets the rules for the zone ID. 218 * <p> 219 * This returns the latest available rules for the zone ID. 220 * <p> 221 * This method relies on time-zone data provider files that are configured. 222 * These are loaded using a {@code ServiceLoader}. 223 * <p> 224 * The caching flag is designed to allow provider implementations to 225 * prevent the rules being cached in {@code ZoneId}. 226 * Under normal circumstances, the caching of zone rules is highly desirable 227 * as it will provide greater performance. However, there is a use case where 228 * the caching would not be desirable, see {@link #provideRules}. 229 * 230 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 231 * @param forCaching whether the rules are being queried for caching, 232 * true if the returned rules will be cached by {@code ZoneId}, 233 * false if they will be returned to the user without being cached in {@code ZoneId} 234 * @return the rules, null if {@code forCaching} is true and this 235 * is a dynamic provider that wants to prevent caching in {@code ZoneId}, 236 * otherwise not null 237 * @throws ZoneRulesException if rules cannot be obtained for the zone ID 238 */ getRules(String zoneId, boolean forCaching)239 public static ZoneRules getRules(String zoneId, boolean forCaching) { 240 Objects.requireNonNull(zoneId, "zoneId"); 241 return getProvider(zoneId).provideRules(zoneId, forCaching); 242 } 243 244 /** 245 * Gets the history of rules for the zone ID. 246 * <p> 247 * Time-zones are defined by governments and change frequently. 248 * This method allows applications to find the history of changes to the 249 * rules for a single zone ID. The map is keyed by a string, which is the 250 * version string associated with the rules. 251 * <p> 252 * The exact meaning and format of the version is provider specific. 253 * The version must follow lexicographical order, thus the returned map will 254 * be order from the oldest known rules to the newest available rules. 255 * The default 'TZDB' group uses version numbering consisting of the year 256 * followed by a letter, such as '2009e' or '2012f'. 257 * <p> 258 * Implementations must provide a result for each valid zone ID, however 259 * they do not have to provide a history of rules. 260 * Thus the map will always contain one element, and will only contain more 261 * than one element if historical rule information is available. 262 * 263 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 264 * @return a modifiable copy of the history of the rules for the ID, sorted 265 * from oldest to newest, not null 266 * @throws ZoneRulesException if history cannot be obtained for the zone ID 267 */ getVersions(String zoneId)268 public static NavigableMap<String, ZoneRules> getVersions(String zoneId) { 269 Objects.requireNonNull(zoneId, "zoneId"); 270 return getProvider(zoneId).provideVersions(zoneId); 271 } 272 273 /** 274 * Gets the provider for the zone ID. 275 * 276 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 277 * @return the provider, not null 278 * @throws ZoneRulesException if the zone ID is unknown 279 */ getProvider(String zoneId)280 private static ZoneRulesProvider getProvider(String zoneId) { 281 ZoneRulesProvider provider = ZONES.get(zoneId); 282 if (provider == null) { 283 if (ZONES.isEmpty()) { 284 throw new ZoneRulesException("No time-zone data files registered"); 285 } 286 throw new ZoneRulesException("Unknown time-zone ID: " + zoneId); 287 } 288 return provider; 289 } 290 291 //------------------------------------------------------------------------- 292 /** 293 * Registers a zone rules provider. 294 * <p> 295 * This adds a new provider to those currently available. 296 * A provider supplies rules for one or more zone IDs. 297 * A provider cannot be registered if it supplies a zone ID that has already been 298 * registered. See the notes on time-zone IDs in {@link ZoneId}, especially 299 * the section on using the concept of a "group" to make IDs unique. 300 * <p> 301 * To ensure the integrity of time-zones already created, there is no way 302 * to deregister providers. 303 * 304 * @param provider the provider to register, not null 305 * @throws ZoneRulesException if a zone ID is already registered 306 */ registerProvider(ZoneRulesProvider provider)307 public static void registerProvider(ZoneRulesProvider provider) { 308 Objects.requireNonNull(provider, "provider"); 309 registerProvider0(provider); 310 PROVIDERS.add(provider); 311 } 312 313 /** 314 * Registers the provider. 315 * 316 * @param provider the provider to register, not null 317 * @throws ZoneRulesException if unable to complete the registration 318 */ registerProvider0(ZoneRulesProvider provider)319 private static synchronized void registerProvider0(ZoneRulesProvider provider) { 320 for (String zoneId : provider.provideZoneIds()) { 321 Objects.requireNonNull(zoneId, "zoneId"); 322 ZoneRulesProvider old = ZONES.putIfAbsent(zoneId, provider); 323 if (old != null) { 324 throw new ZoneRulesException( 325 "Unable to register zone as one already registered with that ID: " + zoneId + 326 ", currently loading from provider: " + provider); 327 } 328 } 329 Set<String> combinedSet = new HashSet<String>(ZONES.keySet()); 330 ZONE_IDS = Collections.unmodifiableSet(combinedSet); 331 } 332 333 /** 334 * Refreshes the rules from the underlying data provider. 335 * <p> 336 * This method allows an application to request that the providers check 337 * for any updates to the provided rules. 338 * After calling this method, the offset stored in any {@link ZonedDateTime} 339 * may be invalid for the zone ID. 340 * <p> 341 * Dynamic update of rules is a complex problem and most applications 342 * should not use this method or dynamic rules. 343 * To achieve dynamic rules, a provider implementation will have to be written 344 * as per the specification of this class. 345 * In addition, instances of {@code ZoneRules} must not be cached in the 346 * application as they will become stale. However, the boolean flag on 347 * {@link #provideRules(String, boolean)} allows provider implementations 348 * to control the caching of {@code ZoneId}, potentially ensuring that 349 * all objects in the system see the new rules. 350 * Note that there is likely to be a cost in performance of a dynamic rules 351 * provider. Note also that no dynamic rules provider is in this specification. 352 * 353 * @return true if the rules were updated 354 * @throws ZoneRulesException if an error occurs during the refresh 355 */ refresh()356 public static boolean refresh() { 357 boolean changed = false; 358 for (ZoneRulesProvider provider : PROVIDERS) { 359 changed |= provider.provideRefresh(); 360 } 361 return changed; 362 } 363 364 /** 365 * Constructor. 366 */ ZoneRulesProvider()367 protected ZoneRulesProvider() { 368 } 369 370 //----------------------------------------------------------------------- 371 /** 372 * SPI method to get the available zone IDs. 373 * <p> 374 * This obtains the IDs that this {@code ZoneRulesProvider} provides. 375 * A provider should provide data for at least one zone ID. 376 * <p> 377 * The returned zone IDs remain available and valid for the lifetime of the application. 378 * A dynamic provider may increase the set of IDs as more data becomes available. 379 * 380 * @return the set of zone IDs being provided, not null 381 * @throws ZoneRulesException if a problem occurs while providing the IDs 382 */ provideZoneIds()383 protected abstract Set<String> provideZoneIds(); 384 385 /** 386 * SPI method to get the rules for the zone ID. 387 * <p> 388 * This loads the rules for the specified zone ID. 389 * The provider implementation must validate that the zone ID is valid and 390 * available, throwing a {@code ZoneRulesException} if it is not. 391 * The result of the method in the valid case depends on the caching flag. 392 * <p> 393 * If the provider implementation is not dynamic, then the result of the 394 * method must be the non-null set of rules selected by the ID. 395 * <p> 396 * If the provider implementation is dynamic, then the flag gives the option 397 * of preventing the returned rules from being cached in {@link ZoneId}. 398 * When the flag is true, the provider is permitted to return null, where 399 * null will prevent the rules from being cached in {@code ZoneId}. 400 * When the flag is false, the provider must return non-null rules. 401 * 402 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 403 * @param forCaching whether the rules are being queried for caching, 404 * true if the returned rules will be cached by {@code ZoneId}, 405 * false if they will be returned to the user without being cached in {@code ZoneId} 406 * @return the rules, null if {@code forCaching} is true and this 407 * is a dynamic provider that wants to prevent caching in {@code ZoneId}, 408 * otherwise not null 409 * @throws ZoneRulesException if rules cannot be obtained for the zone ID 410 */ provideRules(String zoneId, boolean forCaching)411 protected abstract ZoneRules provideRules(String zoneId, boolean forCaching); 412 413 /** 414 * SPI method to get the history of rules for the zone ID. 415 * <p> 416 * This returns a map of historical rules keyed by a version string. 417 * The exact meaning and format of the version is provider specific. 418 * The version must follow lexicographical order, thus the returned map will 419 * be order from the oldest known rules to the newest available rules. 420 * The default 'TZDB' group uses version numbering consisting of the year 421 * followed by a letter, such as '2009e' or '2012f'. 422 * <p> 423 * Implementations must provide a result for each valid zone ID, however 424 * they do not have to provide a history of rules. 425 * Thus the map will contain at least one element, and will only contain 426 * more than one element if historical rule information is available. 427 * <p> 428 * The returned versions remain available and valid for the lifetime of the application. 429 * A dynamic provider may increase the set of versions as more data becomes available. 430 * 431 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 432 * @return a modifiable copy of the history of the rules for the ID, sorted 433 * from oldest to newest, not null 434 * @throws ZoneRulesException if history cannot be obtained for the zone ID 435 */ provideVersions(String zoneId)436 protected abstract NavigableMap<String, ZoneRules> provideVersions(String zoneId); 437 438 /** 439 * SPI method to refresh the rules from the underlying data provider. 440 * <p> 441 * This method provides the opportunity for a provider to dynamically 442 * recheck the underlying data provider to find the latest rules. 443 * This could be used to load new rules without stopping the JVM. 444 * Dynamic behavior is entirely optional and most providers do not support it. 445 * <p> 446 * This implementation returns false. 447 * 448 * @return true if the rules were updated 449 * @throws ZoneRulesException if an error occurs during the refresh 450 */ provideRefresh()451 protected boolean provideRefresh() { 452 return false; 453 } 454 455 } 456