* Time-zone information is categorized as a set of rules defining when and * how the offset from UTC/Greenwich changes. These rules are accessed using * identifiers based on geographical regions, such as countries or states. * The most common region classification is the Time Zone Database (TZDB), * which defines regions such as 'Europe/Paris' and 'Asia/Tokyo'. *
* The region identifier, modeled by this class, is distinct from the * underlying rules, modeled by {@link ZoneRules}. * The rules are defined by governments and change frequently. * By contrast, the region identifier is well-defined and long-lived. * This separation also allows rules to be shared between regions if appropriate. * * @implSpec * This class is immutable and thread-safe. * * @since 1.8 */ final class ZoneRegion extends ZoneId implements Serializable { /** * Serialization version. */ private static final long serialVersionUID = 8386373296231747096L; /** * The time-zone ID, not null. */ private final String id; /** * The time-zone rules, null if zone ID was loaded leniently. */ private final transient ZoneRules rules; /** * Obtains an instance of {@code ZoneId} from an identifier. * * @param zoneId the time-zone ID, not null * @param checkAvailable whether to check if the zone ID is available * @return the zone ID, not null * @throws DateTimeException if the ID format is invalid * @throws ZoneRulesException if checking availability and the ID cannot be found */ static ZoneRegion ofId(String zoneId, boolean checkAvailable) { Objects.requireNonNull(zoneId, "zoneId"); checkName(zoneId); ZoneRules rules = null; try { // always attempt load for better behavior after deserialization rules = ZoneRulesProvider.getRules(zoneId, true); } catch (ZoneRulesException ex) { if (checkAvailable) { throw ex; } } return new ZoneRegion(zoneId, rules); } /** * Checks that the given string is a legal ZondId name. * * @param zoneId the time-zone ID, not null * @throws DateTimeException if the ID format is invalid */ private static void checkName(String zoneId) { int n = zoneId.length(); if (n < 2) { throw new DateTimeException("Invalid ID for region-based ZoneId, invalid format: " + zoneId); } for (int i = 0; i < n; i++) { char c = zoneId.charAt(i); if (c >= 'a' && c <= 'z') continue; if (c >= 'A' && c <= 'Z') continue; if (c == '/' && i != 0) continue; if (c >= '0' && c <= '9' && i != 0) continue; if (c == '~' && i != 0) continue; if (c == '.' && i != 0) continue; if (c == '_' && i != 0) continue; if (c == '+' && i != 0) continue; if (c == '-' && i != 0) continue; throw new DateTimeException("Invalid ID for region-based ZoneId, invalid format: " + zoneId); } } //------------------------------------------------------------------------- /** * Constructor. * * @param id the time-zone ID, not null * @param rules the rules, null for lazy lookup */ ZoneRegion(String id, ZoneRules rules) { this.id = id; this.rules = rules; } //----------------------------------------------------------------------- @Override public String getId() { return id; } @Override public ZoneRules getRules() { // additional query for group provider when null allows for possibility // that the provider was updated after the ZoneId was created return (rules != null ? rules : ZoneRulesProvider.getRules(id, false)); } //----------------------------------------------------------------------- /** * Writes the object using a * dedicated serialized form. *
* out.writeByte(7); // identifies this as a ZoneId (not ZoneOffset)
* out.writeUTF(zoneId);
*
*
* @return the instance of {@code Ser}, not null
*/
private Object writeReplace() {
return new Ser(Ser.ZONE_REGION_TYPE, this);
}
/**
* Defend against malicious streams.
* @return never
* @throws InvalidObjectException always
*/
private Object readResolve() throws ObjectStreamException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
@Override
void write(DataOutput out) throws IOException {
out.writeByte(Ser.ZONE_REGION_TYPE);
writeExternal(out);
}
void writeExternal(DataOutput out) throws IOException {
out.writeUTF(id);
}
static ZoneId readExternal(DataInput in) throws IOException {
String id = in.readUTF();
return ZoneId.of(id, false);
}
}