1 /* 2 * Copyright (c) 2012, 2013, 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 81 /** 82 * Provider of time-zone rules to the system. 83 * <p> 84 * This class manages the configuration of time-zone rules. 85 * The static methods provide the public API that can be used to manage the providers. 86 * The abstract methods provide the SPI that allows rules to be provided. 87 * <p> 88 * ZoneRulesProvider may be installed in an instance of the Java Platform as 89 * extension classes, that is, jar files placed into any of the usual extension 90 * directories. Installed providers are loaded using the service-provider loading 91 * facility defined by the {@link ServiceLoader} class. A ZoneRulesProvider 92 * identifies itself with a provider configuration file named 93 * {@code java.time.zone.ZoneRulesProvider} in the resource directory 94 * {@code META-INF/services}. The file should contain a line that specifies the 95 * fully qualified concrete zonerules-provider class name. 96 * Providers may also be made available by adding them to the class path or by 97 * registering themselves via {@link #registerProvider} method. 98 * <p> 99 * The Java virtual machine has a default provider that provides zone rules 100 * for the time-zones defined by IANA Time Zone Database (TZDB). If the system 101 * property {@code java.time.zone.DefaultZoneRulesProvider} is defined then 102 * it is taken to be the fully-qualified name of a concrete ZoneRulesProvider 103 * class to be loaded as the default provider, using the system class loader. 104 * If this system property is not defined, a system-default provider will be 105 * loaded to serve as the default provider. 106 * <p> 107 * Rules are looked up primarily by zone ID, as used by {@link ZoneId}. 108 * Only zone region IDs may be used, zone offset IDs are not used here. 109 * <p> 110 * Time-zone rules are political, thus the data can change at any time. 111 * Each provider will provide the latest rules for each zone ID, but they 112 * may also provide the history of how the rules changed. 113 * 114 * @implSpec 115 * This interface is a service provider that can be called by multiple threads. 116 * Implementations must be immutable and thread-safe. 117 * <p> 118 * Providers must ensure that once a rule has been seen by the application, the 119 * rule must continue to be available. 120 * <p> 121 * Providers are encouraged to implement a meaningful {@code toString} method. 122 * <p> 123 * Many systems would like to update time-zone rules dynamically without stopping the JVM. 124 * When examined in detail, this is a complex problem. 125 * Providers may choose to handle dynamic updates, however the default provider does not. 126 * 127 * @since 1.8 128 */ 129 public abstract class ZoneRulesProvider { 130 131 /** 132 * The set of loaded providers. 133 */ 134 private static final CopyOnWriteArrayList<ZoneRulesProvider> PROVIDERS = new CopyOnWriteArrayList<>(); 135 /** 136 * The lookup from zone ID to provider. 137 */ 138 private static final ConcurrentMap<String, ZoneRulesProvider> ZONES = new ConcurrentHashMap<>(512, 0.75f, 2); 139 140 static { 141 // Android-changed: use a single hard-coded provider. 142 ZoneRulesProvider provider = new IcuZoneRulesProvider(); 143 registerProvider(provider); 144 } 145 146 //------------------------------------------------------------------------- 147 /** 148 * Gets the set of available zone IDs. 149 * <p> 150 * These IDs are the string form of a {@link ZoneId}. 151 * 152 * @return a modifiable copy of the set of zone IDs, not null 153 */ getAvailableZoneIds()154 public static Set<String> getAvailableZoneIds() { 155 return new HashSet<>(ZONES.keySet()); 156 } 157 158 /** 159 * Gets the rules for the zone ID. 160 * <p> 161 * This returns the latest available rules for the zone ID. 162 * <p> 163 * This method relies on time-zone data provider files that are configured. 164 * These are loaded using a {@code ServiceLoader}. 165 * <p> 166 * The caching flag is designed to allow provider implementations to 167 * prevent the rules being cached in {@code ZoneId}. 168 * Under normal circumstances, the caching of zone rules is highly desirable 169 * as it will provide greater performance. However, there is a use case where 170 * the caching would not be desirable, see {@link #provideRules}. 171 * 172 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 173 * @param forCaching whether the rules are being queried for caching, 174 * true if the returned rules will be cached by {@code ZoneId}, 175 * false if they will be returned to the user without being cached in {@code ZoneId} 176 * @return the rules, null if {@code forCaching} is true and this 177 * is a dynamic provider that wants to prevent caching in {@code ZoneId}, 178 * otherwise not null 179 * @throws ZoneRulesException if rules cannot be obtained for the zone ID 180 */ getRules(String zoneId, boolean forCaching)181 public static ZoneRules getRules(String zoneId, boolean forCaching) { 182 Objects.requireNonNull(zoneId, "zoneId"); 183 return getProvider(zoneId).provideRules(zoneId, forCaching); 184 } 185 186 /** 187 * Gets the history of rules for the zone ID. 188 * <p> 189 * Time-zones are defined by governments and change frequently. 190 * This method allows applications to find the history of changes to the 191 * rules for a single zone ID. The map is keyed by a string, which is the 192 * version string associated with the rules. 193 * <p> 194 * The exact meaning and format of the version is provider specific. 195 * The version must follow lexicographical order, thus the returned map will 196 * be order from the oldest known rules to the newest available rules. 197 * The default 'TZDB' group uses version numbering consisting of the year 198 * followed by a letter, such as '2009e' or '2012f'. 199 * <p> 200 * Implementations must provide a result for each valid zone ID, however 201 * they do not have to provide a history of rules. 202 * Thus the map will always contain one element, and will only contain more 203 * than one element if historical rule information is available. 204 * 205 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 206 * @return a modifiable copy of the history of the rules for the ID, sorted 207 * from oldest to newest, not null 208 * @throws ZoneRulesException if history cannot be obtained for the zone ID 209 */ getVersions(String zoneId)210 public static NavigableMap<String, ZoneRules> getVersions(String zoneId) { 211 Objects.requireNonNull(zoneId, "zoneId"); 212 return getProvider(zoneId).provideVersions(zoneId); 213 } 214 215 /** 216 * Gets the provider for the zone ID. 217 * 218 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 219 * @return the provider, not null 220 * @throws ZoneRulesException if the zone ID is unknown 221 */ getProvider(String zoneId)222 private static ZoneRulesProvider getProvider(String zoneId) { 223 ZoneRulesProvider provider = ZONES.get(zoneId); 224 if (provider == null) { 225 if (ZONES.isEmpty()) { 226 throw new ZoneRulesException("No time-zone data files registered"); 227 } 228 throw new ZoneRulesException("Unknown time-zone ID: " + zoneId); 229 } 230 return provider; 231 } 232 233 //------------------------------------------------------------------------- 234 /** 235 * Registers a zone rules provider. 236 * <p> 237 * This adds a new provider to those currently available. 238 * A provider supplies rules for one or more zone IDs. 239 * A provider cannot be registered if it supplies a zone ID that has already been 240 * registered. See the notes on time-zone IDs in {@link ZoneId}, especially 241 * the section on using the concept of a "group" to make IDs unique. 242 * <p> 243 * To ensure the integrity of time-zones already created, there is no way 244 * to deregister providers. 245 * 246 * @param provider the provider to register, not null 247 * @throws ZoneRulesException if a zone ID is already registered 248 */ registerProvider(ZoneRulesProvider provider)249 public static void registerProvider(ZoneRulesProvider provider) { 250 Objects.requireNonNull(provider, "provider"); 251 registerProvider0(provider); 252 PROVIDERS.add(provider); 253 } 254 255 /** 256 * Registers the provider. 257 * 258 * @param provider the provider to register, not null 259 * @throws ZoneRulesException if unable to complete the registration 260 */ registerProvider0(ZoneRulesProvider provider)261 private static void registerProvider0(ZoneRulesProvider provider) { 262 for (String zoneId : provider.provideZoneIds()) { 263 Objects.requireNonNull(zoneId, "zoneId"); 264 ZoneRulesProvider old = ZONES.putIfAbsent(zoneId, provider); 265 if (old != null) { 266 throw new ZoneRulesException( 267 "Unable to register zone as one already registered with that ID: " + zoneId + 268 ", currently loading from provider: " + provider); 269 } 270 } 271 } 272 273 /** 274 * Refreshes the rules from the underlying data provider. 275 * <p> 276 * This method allows an application to request that the providers check 277 * for any updates to the provided rules. 278 * After calling this method, the offset stored in any {@link ZonedDateTime} 279 * may be invalid for the zone ID. 280 * <p> 281 * Dynamic update of rules is a complex problem and most applications 282 * should not use this method or dynamic rules. 283 * To achieve dynamic rules, a provider implementation will have to be written 284 * as per the specification of this class. 285 * In addition, instances of {@code ZoneRules} must not be cached in the 286 * application as they will become stale. However, the boolean flag on 287 * {@link #provideRules(String, boolean)} allows provider implementations 288 * to control the caching of {@code ZoneId}, potentially ensuring that 289 * all objects in the system see the new rules. 290 * Note that there is likely to be a cost in performance of a dynamic rules 291 * provider. Note also that no dynamic rules provider is in this specification. 292 * 293 * @return true if the rules were updated 294 * @throws ZoneRulesException if an error occurs during the refresh 295 */ refresh()296 public static boolean refresh() { 297 boolean changed = false; 298 for (ZoneRulesProvider provider : PROVIDERS) { 299 changed |= provider.provideRefresh(); 300 } 301 return changed; 302 } 303 304 /** 305 * Constructor. 306 */ ZoneRulesProvider()307 protected ZoneRulesProvider() { 308 } 309 310 //----------------------------------------------------------------------- 311 /** 312 * SPI method to get the available zone IDs. 313 * <p> 314 * This obtains the IDs that this {@code ZoneRulesProvider} provides. 315 * A provider should provide data for at least one zone ID. 316 * <p> 317 * The returned zone IDs remain available and valid for the lifetime of the application. 318 * A dynamic provider may increase the set of IDs as more data becomes available. 319 * 320 * @return the set of zone IDs being provided, not null 321 * @throws ZoneRulesException if a problem occurs while providing the IDs 322 */ provideZoneIds()323 protected abstract Set<String> provideZoneIds(); 324 325 /** 326 * SPI method to get the rules for the zone ID. 327 * <p> 328 * This loads the rules for the specified zone ID. 329 * The provider implementation must validate that the zone ID is valid and 330 * available, throwing a {@code ZoneRulesException} if it is not. 331 * The result of the method in the valid case depends on the caching flag. 332 * <p> 333 * If the provider implementation is not dynamic, then the result of the 334 * method must be the non-null set of rules selected by the ID. 335 * <p> 336 * If the provider implementation is dynamic, then the flag gives the option 337 * of preventing the returned rules from being cached in {@link ZoneId}. 338 * When the flag is true, the provider is permitted to return null, where 339 * null will prevent the rules from being cached in {@code ZoneId}. 340 * When the flag is false, the provider must return non-null rules. 341 * 342 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 343 * @param forCaching whether the rules are being queried for caching, 344 * true if the returned rules will be cached by {@code ZoneId}, 345 * false if they will be returned to the user without being cached in {@code ZoneId} 346 * @return the rules, null if {@code forCaching} is true and this 347 * is a dynamic provider that wants to prevent caching in {@code ZoneId}, 348 * otherwise not null 349 * @throws ZoneRulesException if rules cannot be obtained for the zone ID 350 */ provideRules(String zoneId, boolean forCaching)351 protected abstract ZoneRules provideRules(String zoneId, boolean forCaching); 352 353 /** 354 * SPI method to get the history of rules for the zone ID. 355 * <p> 356 * This returns a map of historical rules keyed by a version string. 357 * The exact meaning and format of the version is provider specific. 358 * The version must follow lexicographical order, thus the returned map will 359 * be order from the oldest known rules to the newest available rules. 360 * The default 'TZDB' group uses version numbering consisting of the year 361 * followed by a letter, such as '2009e' or '2012f'. 362 * <p> 363 * Implementations must provide a result for each valid zone ID, however 364 * they do not have to provide a history of rules. 365 * Thus the map will contain at least one element, and will only contain 366 * more than one element if historical rule information is available. 367 * <p> 368 * The returned versions remain available and valid for the lifetime of the application. 369 * A dynamic provider may increase the set of versions as more data becomes available. 370 * 371 * @param zoneId the zone ID as defined by {@code ZoneId}, not null 372 * @return a modifiable copy of the history of the rules for the ID, sorted 373 * from oldest to newest, not null 374 * @throws ZoneRulesException if history cannot be obtained for the zone ID 375 */ provideVersions(String zoneId)376 protected abstract NavigableMap<String, ZoneRules> provideVersions(String zoneId); 377 378 /** 379 * SPI method to refresh the rules from the underlying data provider. 380 * <p> 381 * This method provides the opportunity for a provider to dynamically 382 * recheck the underlying data provider to find the latest rules. 383 * This could be used to load new rules without stopping the JVM. 384 * Dynamic behavior is entirely optional and most providers do not support it. 385 * <p> 386 * This implementation returns false. 387 * 388 * @return true if the rules were updated 389 * @throws ZoneRulesException if an error occurs during the refresh 390 */ provideRefresh()391 protected boolean provideRefresh() { 392 return false; 393 } 394 395 } 396