zoukankan      html  css  js  c++  java
  • GMT+8 -8

    /*
     * Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved.
     * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     *
     */
    
    /*
     * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
     * (C) Copyright IBM Corp. 1996 - All Rights Reserved
     *
     *   The original version of this source code and documentation is copyrighted
     * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
     * materials are provided under terms of a License Agreement between Taligent
     * and Sun. This technology is protected by multiple US and International
     * patents. This notice and attribution to Taligent may not be removed.
     *   Taligent is a registered trademark of Taligent, Inc.
     *
     */
    
    package java.util;
    
    import java.io.Serializable;
    import java.security.AccessController;
    import java.security.PrivilegedAction;
    import java.time.ZoneId;
    import sun.security.action.GetPropertyAction;
    import sun.util.calendar.ZoneInfo;
    import sun.util.calendar.ZoneInfoFile;
    import sun.util.locale.provider.TimeZoneNameUtility;
    
    /**
     * <code>TimeZone</code> represents a time zone offset, and also figures out daylight
     * savings.
     *
     * <p>
     * Typically, you get a <code>TimeZone</code> using <code>getDefault</code>
     * which creates a <code>TimeZone</code> based on the time zone where the program
     * is running. For example, for a program running in Japan, <code>getDefault</code>
     * creates a <code>TimeZone</code> object based on Japanese Standard Time.
     *
     * <p>
     * You can also get a <code>TimeZone</code> using <code>getTimeZone</code>
     * along with a time zone ID. For instance, the time zone ID for the
     * U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a
     * U.S. Pacific Time <code>TimeZone</code> object with:
     * <blockquote><pre>
     * TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
     * </pre></blockquote>
     * You can use the <code>getAvailableIDs</code> method to iterate through
     * all the supported time zone IDs. You can then choose a
     * supported ID to get a <code>TimeZone</code>.
     * If the time zone you want is not represented by one of the
     * supported IDs, then a custom time zone ID can be specified to
     * produce a TimeZone. The syntax of a custom time zone ID is:
     *
     * <blockquote><pre>
     * <a name="CustomID"><i>CustomID:</i></a>
     *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i>
     *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <i>Minutes</i>
     *         <code>GMT</code> <i>Sign</i> <i>Hours</i>
     * <i>Sign:</i> one of
     *         <code>+ -</code>
     * <i>Hours:</i>
     *         <i>Digit</i>
     *         <i>Digit</i> <i>Digit</i>
     * <i>Minutes:</i>
     *         <i>Digit</i> <i>Digit</i>
     * <i>Digit:</i> one of
     *         <code>0 1 2 3 4 5 6 7 8 9</code>
     * </pre></blockquote>
     *
     * <i>Hours</i> must be between 0 to 23 and <i>Minutes</i> must be
     * between 00 to 59.  For example, "GMT+10" and "GMT+0010" mean ten
     * hours and ten minutes ahead of GMT, respectively.
     * <p>
     * The format is locale independent and digits must be taken from the
     * Basic Latin block of the Unicode standard. No daylight saving time
     * transition schedule can be specified with a custom time zone ID. If
     * the specified string doesn't match the syntax, <code>"GMT"</code>
     * is used.
     * <p>
     * When creating a <code>TimeZone</code>, the specified custom time
     * zone ID is normalized in the following syntax:
     * <blockquote><pre>
     * <a name="NormalizedCustomID"><i>NormalizedCustomID:</i></a>
     *         <code>GMT</code> <i>Sign</i> <i>TwoDigitHours</i> <code>:</code> <i>Minutes</i>
     * <i>Sign:</i> one of
     *         <code>+ -</code>
     * <i>TwoDigitHours:</i>
     *         <i>Digit</i> <i>Digit</i>
     * <i>Minutes:</i>
     *         <i>Digit</i> <i>Digit</i>
     * <i>Digit:</i> one of
     *         <code>0 1 2 3 4 5 6 7 8 9</code>
     * </pre></blockquote>
     * For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".
     *
     * <h3>Three-letter time zone IDs</h3>
     *
     * For compatibility with JDK 1.1.x, some other three-letter time zone IDs
     * (such as "PST", "CTT", "AST") are also supported. However, <strong>their
     * use is deprecated</strong> because the same abbreviation is often used
     * for multiple time zones (for example, "CST" could be U.S. "Central Standard
     * Time" and "China Standard Time"), and the Java platform can then only
     * recognize one of them.
     *
     *
     * @see          Calendar
     * @see          GregorianCalendar
     * @see          SimpleTimeZone
     * @author       Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
     * @since        JDK1.1
     */
    abstract public class TimeZone implements Serializable, Cloneable {
        /**
         * Sole constructor.  (For invocation by subclass constructors, typically
         * implicit.)
         */
        public TimeZone() {
        }
    
        /**
         * A style specifier for <code>getDisplayName()</code> indicating
         * a short name, such as "PST."
         * @see #LONG
         * @since 1.2
         */
        public static final int SHORT = 0;
    
        /**
         * A style specifier for <code>getDisplayName()</code> indicating
         * a long name, such as "Pacific Standard Time."
         * @see #SHORT
         * @since 1.2
         */
        public static final int LONG  = 1;
    
        // Constants used internally; unit is milliseconds
        private static final int ONE_MINUTE = 60*1000;
        private static final int ONE_HOUR   = 60*ONE_MINUTE;
        private static final int ONE_DAY    = 24*ONE_HOUR;
    
        // Proclaim serialization compatibility with JDK 1.1
        static final long serialVersionUID = 3581463369166924961L;
    
        /**
         * Gets the time zone offset, for current date, modified in case of
         * daylight savings. This is the offset to add to UTC to get local time.
         * <p>
         * This method returns a historically correct offset if an
         * underlying <code>TimeZone</code> implementation subclass
         * supports historical Daylight Saving Time schedule and GMT
         * offset changes.
         *
         * @param era the era of the given date.
         * @param year the year in the given date.
         * @param month the month in the given date.
         * Month is 0-based. e.g., 0 for January.
         * @param day the day-in-month of the given date.
         * @param dayOfWeek the day-of-week of the given date.
         * @param milliseconds the milliseconds in day in <em>standard</em>
         * local time.
         *
         * @return the offset in milliseconds to add to GMT to get local time.
         *
         * @see Calendar#ZONE_OFFSET
         * @see Calendar#DST_OFFSET
         */
        public abstract int getOffset(int era, int year, int month, int day,
                                      int dayOfWeek, int milliseconds);
    
        /**
         * Returns the offset of this time zone from UTC at the specified
         * date. If Daylight Saving Time is in effect at the specified
         * date, the offset value is adjusted with the amount of daylight
         * saving.
         * <p>
         * This method returns a historically correct offset value if an
         * underlying TimeZone implementation subclass supports historical
         * Daylight Saving Time schedule and GMT offset changes.
         *
         * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT
         * @return the amount of time in milliseconds to add to UTC to get local time.
         *
         * @see Calendar#ZONE_OFFSET
         * @see Calendar#DST_OFFSET
         * @since 1.4
         */
        public int getOffset(long date) {
            if (inDaylightTime(new Date(date))) {
                return getRawOffset() + getDSTSavings();
            }
            return getRawOffset();
        }
    
        /**
         * Gets the raw GMT offset and the amount of daylight saving of this
         * time zone at the given time.
         * @param date the milliseconds (since January 1, 1970,
         * 00:00:00.000 GMT) at which the time zone offset and daylight
         * saving amount are found
         * @param offsets an array of int where the raw GMT offset
         * (offset[0]) and daylight saving amount (offset[1]) are stored,
         * or null if those values are not needed. The method assumes that
         * the length of the given array is two or larger.
         * @return the total amount of the raw GMT offset and daylight
         * saving at the specified date.
         *
         * @see Calendar#ZONE_OFFSET
         * @see Calendar#DST_OFFSET
         */
        int getOffsets(long date, int[] offsets) {
            int rawoffset = getRawOffset();
            int dstoffset = 0;
            if (inDaylightTime(new Date(date))) {
                dstoffset = getDSTSavings();
            }
            if (offsets != null) {
                offsets[0] = rawoffset;
                offsets[1] = dstoffset;
            }
            return rawoffset + dstoffset;
        }
    
        /**
         * Sets the base time zone offset to GMT.
         * This is the offset to add to UTC to get local time.
         * <p>
         * If an underlying <code>TimeZone</code> implementation subclass
         * supports historical GMT offset changes, the specified GMT
         * offset is set as the latest GMT offset and the difference from
         * the known latest GMT offset value is used to adjust all
         * historical GMT offset values.
         *
         * @param offsetMillis the given base time zone offset to GMT.
         */
        abstract public void setRawOffset(int offsetMillis);
    
        /**
         * Returns the amount of time in milliseconds to add to UTC to get
         * standard time in this time zone. Because this value is not
         * affected by daylight saving time, it is called <I>raw
         * offset</I>.
         * <p>
         * If an underlying <code>TimeZone</code> implementation subclass
         * supports historical GMT offset changes, the method returns the
         * raw offset value of the current date. In Honolulu, for example,
         * its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and
         * this method always returns -36000000 milliseconds (i.e., -10
         * hours).
         *
         * @return the amount of raw offset time in milliseconds to add to UTC.
         * @see Calendar#ZONE_OFFSET
         */
        public abstract int getRawOffset();
    
        /**
         * Gets the ID of this time zone.
         * @return the ID of this time zone.
         */
        public String getID()
        {
            return ID;
        }
    
        /**
         * Sets the time zone ID. This does not change any other data in
         * the time zone object.
         * @param ID the new time zone ID.
         */
        public void setID(String ID)
        {
            if (ID == null) {
                throw new NullPointerException();
            }
            this.ID = ID;
        }
    
        /**
         * Returns a long standard time name of this {@code TimeZone} suitable for
         * presentation to the user in the default locale.
         *
         * <p>This method is equivalent to:
         * <blockquote><pre>
         * getDisplayName(false, {@link #LONG},
         *                Locale.getDefault({@link Locale.Category#DISPLAY}))
         * </pre></blockquote>
         *
         * @return the human-readable name of this time zone in the default locale.
         * @since 1.2
         * @see #getDisplayName(boolean, int, Locale)
         * @see Locale#getDefault(Locale.Category)
         * @see Locale.Category
         */
        public final String getDisplayName() {
            return getDisplayName(false, LONG,
                                  Locale.getDefault(Locale.Category.DISPLAY));
        }
    
        /**
         * Returns a long standard time name of this {@code TimeZone} suitable for
         * presentation to the user in the specified {@code locale}.
         *
         * <p>This method is equivalent to:
         * <blockquote><pre>
         * getDisplayName(false, {@link #LONG}, locale)
         * </pre></blockquote>
         *
         * @param locale the locale in which to supply the display name.
         * @return the human-readable name of this time zone in the given locale.
         * @exception NullPointerException if {@code locale} is {@code null}.
         * @since 1.2
         * @see #getDisplayName(boolean, int, Locale)
         */
        public final String getDisplayName(Locale locale) {
            return getDisplayName(false, LONG, locale);
        }
    
        /**
         * Returns a name in the specified {@code style} of this {@code TimeZone}
         * suitable for presentation to the user in the default locale. If the
         * specified {@code daylight} is {@code true}, a Daylight Saving Time name
         * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving
         * Time). Otherwise, a Standard Time name is returned.
         *
         * <p>This method is equivalent to:
         * <blockquote><pre>
         * getDisplayName(daylight, style,
         *                Locale.getDefault({@link Locale.Category#DISPLAY}))
         * </pre></blockquote>
         *
         * @param daylight {@code true} specifying a Daylight Saving Time name, or
         *                 {@code false} specifying a Standard Time name
         * @param style either {@link #LONG} or {@link #SHORT}
         * @return the human-readable name of this time zone in the default locale.
         * @exception IllegalArgumentException if {@code style} is invalid.
         * @since 1.2
         * @see #getDisplayName(boolean, int, Locale)
         * @see Locale#getDefault(Locale.Category)
         * @see Locale.Category
         * @see java.text.DateFormatSymbols#getZoneStrings()
         */
        public final String getDisplayName(boolean daylight, int style) {
            return getDisplayName(daylight, style,
                                  Locale.getDefault(Locale.Category.DISPLAY));
        }
    
        /**
         * Returns a name in the specified {@code style} of this {@code TimeZone}
         * suitable for presentation to the user in the specified {@code
         * locale}. If the specified {@code daylight} is {@code true}, a Daylight
         * Saving Time name is returned (even if this {@code TimeZone} doesn't
         * observe Daylight Saving Time). Otherwise, a Standard Time name is
         * returned.
         *
         * <p>When looking up a time zone name, the {@linkplain
         * ResourceBundle.Control#getCandidateLocales(String,Locale) default
         * <code>Locale</code> search path of <code>ResourceBundle</code>} derived
         * from the specified {@code locale} is used. (No {@linkplain
         * ResourceBundle.Control#getFallbackLocale(String,Locale) fallback
         * <code>Locale</code>} search is performed.) If a time zone name in any
         * {@code Locale} of the search path, including {@link Locale#ROOT}, is
         * found, the name is returned. Otherwise, a string in the
         * <a href="#NormalizedCustomID">normalized custom ID format</a> is returned.
         *
         * @param daylight {@code true} specifying a Daylight Saving Time name, or
         *                 {@code false} specifying a Standard Time name
         * @param style either {@link #LONG} or {@link #SHORT}
         * @param locale   the locale in which to supply the display name.
         * @return the human-readable name of this time zone in the given locale.
         * @exception IllegalArgumentException if {@code style} is invalid.
         * @exception NullPointerException if {@code locale} is {@code null}.
         * @since 1.2
         * @see java.text.DateFormatSymbols#getZoneStrings()
         */
        public String getDisplayName(boolean daylight, int style, Locale locale) {
            if (style != SHORT && style != LONG) {
                throw new IllegalArgumentException("Illegal style: " + style);
            }
            String id = getID();
            String name = TimeZoneNameUtility.retrieveDisplayName(id, daylight, style, locale);
            if (name != null) {
                return name;
            }
    
            if (id.startsWith("GMT") && id.length() > 3) {
                char sign = id.charAt(3);
                if (sign == '+' || sign == '-') {
                    return id;
                }
            }
            int offset = getRawOffset();
            if (daylight) {
                offset += getDSTSavings();
            }
            return ZoneInfoFile.toCustomID(offset);
        }
    
        private static String[] getDisplayNames(String id, Locale locale) {
            return TimeZoneNameUtility.retrieveDisplayNames(id, locale);
        }
    
        /**
         * Returns the amount of time to be added to local standard time
         * to get local wall clock time.
         *
         * <p>The default implementation returns 3600000 milliseconds
         * (i.e., one hour) if a call to {@link #useDaylightTime()}
         * returns {@code true}. Otherwise, 0 (zero) is returned.
         *
         * <p>If an underlying {@code TimeZone} implementation subclass
         * supports historical and future Daylight Saving Time schedule
         * changes, this method returns the amount of saving time of the
         * last known Daylight Saving Time rule that can be a future
         * prediction.
         *
         * <p>If the amount of saving time at any given time stamp is
         * required, construct a {@link Calendar} with this {@code
         * TimeZone} and the time stamp, and call {@link Calendar#get(int)
         * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}.
         *
         * @return the amount of saving time in milliseconds
         * @since 1.4
         * @see #inDaylightTime(Date)
         * @see #getOffset(long)
         * @see #getOffset(int,int,int,int,int,int)
         * @see Calendar#ZONE_OFFSET
         */
        public int getDSTSavings() {
            if (useDaylightTime()) {
                return 3600000;
            }
            return 0;
        }
    
        /**
         * Queries if this {@code TimeZone} uses Daylight Saving Time.
         *
         * <p>If an underlying {@code TimeZone} implementation subclass
         * supports historical and future Daylight Saving Time schedule
         * changes, this method refers to the last known Daylight Saving Time
         * rule that can be a future prediction and may not be the same as
         * the current rule. Consider calling {@link #observesDaylightTime()}
         * if the current rule should also be taken into account.
         *
         * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time,
         *         {@code false}, otherwise.
         * @see #inDaylightTime(Date)
         * @see Calendar#DST_OFFSET
         */
        public abstract boolean useDaylightTime();
    
        /**
         * Returns {@code true} if this {@code TimeZone} is currently in
         * Daylight Saving Time, or if a transition from Standard Time to
         * Daylight Saving Time occurs at any future time.
         *
         * <p>The default implementation returns {@code true} if
         * {@code useDaylightTime()} or {@code inDaylightTime(new Date())}
         * returns {@code true}.
         *
         * @return {@code true} if this {@code TimeZone} is currently in
         * Daylight Saving Time, or if a transition from Standard Time to
         * Daylight Saving Time occurs at any future time; {@code false}
         * otherwise.
         * @since 1.7
         * @see #useDaylightTime()
         * @see #inDaylightTime(Date)
         * @see Calendar#DST_OFFSET
         */
        public boolean observesDaylightTime() {
            return useDaylightTime() || inDaylightTime(new Date());
        }
    
        /**
         * Queries if the given {@code date} is in Daylight Saving Time in
         * this time zone.
         *
         * @param date the given Date.
         * @return {@code true} if the given date is in Daylight Saving Time,
         *         {@code false}, otherwise.
         */
        abstract public boolean inDaylightTime(Date date);
    
        /**
         * Gets the <code>TimeZone</code> for the given ID.
         *
         * @param ID the ID for a <code>TimeZone</code>, either an abbreviation
         * such as "PST", a full name such as "America/Los_Angeles", or a custom
         * ID such as "GMT-8:00". Note that the support of abbreviations is
         * for JDK 1.1.x compatibility only and full names should be used.
         *
         * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID
         * cannot be understood.
         */
        public static synchronized TimeZone getTimeZone(String ID) {
            return getTimeZone(ID, true);
        }
    
        /**
         * Gets the {@code TimeZone} for the given {@code zoneId}.
         *
         * @param zoneId a {@link ZoneId} from which the time zone ID is obtained
         * @return the specified {@code TimeZone}, or the GMT zone if the given ID
         *         cannot be understood.
         * @throws NullPointerException if {@code zoneId} is {@code null}
         * @since 1.8
         */
        public static TimeZone getTimeZone(ZoneId zoneId) {
            String tzid = zoneId.getId(); // throws an NPE if null
            char c = tzid.charAt(0);
            if (c == '+' || c == '-') {
                tzid = "GMT" + tzid;
            } else if (c == 'Z' && tzid.length() == 1) {
                tzid = "UTC";
            }
            return getTimeZone(tzid, true);
        }
    
        /**
         * Converts this {@code TimeZone} object to a {@code ZoneId}.
         *
         * @return a {@code ZoneId} representing the same time zone as this
         *         {@code TimeZone}
         * @since 1.8
         */
        public ZoneId toZoneId() {
            String id = getID();
            if (ZoneInfoFile.useOldMapping() && id.length() == 3) {
                if ("EST".equals(id))
                    return ZoneId.of("America/New_York");
                if ("MST".equals(id))
                    return ZoneId.of("America/Denver");
                if ("HST".equals(id))
                    return ZoneId.of("America/Honolulu");
            }
            return ZoneId.of(id, ZoneId.SHORT_IDS);
        }
    
        private static TimeZone getTimeZone(String ID, boolean fallback) {
            TimeZone tz = ZoneInfo.getTimeZone(ID);
            if (tz == null) {
                tz = parseCustomTimeZone(ID);
                if (tz == null && fallback) {
                    tz = new ZoneInfo(GMT_ID, 0);
                }
            }
            return tz;
        }
    
        /**
         * Gets the available IDs according to the given time zone offset in milliseconds.
         *
         * @param rawOffset the given time zone GMT offset in milliseconds.
         * @return an array of IDs, where the time zone for that ID has
         * the specified GMT offset. For example, "America/Phoenix" and "America/Denver"
         * both have GMT-07:00, but differ in daylight saving behavior.
         * @see #getRawOffset()
         */
        public static synchronized String[] getAvailableIDs(int rawOffset) {
            return ZoneInfo.getAvailableIDs(rawOffset);
        }
    
        /**
         * Gets all the available IDs supported.
         * @return an array of IDs.
         */
        public static synchronized String[] getAvailableIDs() {
            return ZoneInfo.getAvailableIDs();
        }
    
        /**
         * Gets the platform defined TimeZone ID.
         **/
        private static native String getSystemTimeZoneID(String javaHome);
    
        /**
         * Gets the custom time zone ID based on the GMT offset of the
         * platform. (e.g., "GMT+08:00")
         */
        private static native String getSystemGMTOffsetID();
    
        /**
         * Gets the default {@code TimeZone} of the Java virtual machine. If the
         * cached default {@code TimeZone} is available, its clone is returned.
         * Otherwise, the method takes the following steps to determine the default
         * time zone.
         *
         * <ul>
         * <li>Use the {@code user.timezone} property value as the default
         * time zone ID if it's available.</li>
         * <li>Detect the platform time zone ID. The source of the
         * platform time zone and ID mapping may vary with implementation.</li>
         * <li>Use {@code GMT} as the last resort if the given or detected
         * time zone ID is unknown.</li>
         * </ul>
         *
         * <p>The default {@code TimeZone} created from the ID is cached,
         * and its clone is returned. The {@code user.timezone} property
         * value is set to the ID upon return.
         *
         * @return the default {@code TimeZone}
         * @see #setDefault(TimeZone)
         */
        public static TimeZone getDefault() {
            return (TimeZone) getDefaultRef().clone();
        }
    
        /**
         * Returns the reference to the default TimeZone object. This
         * method doesn't create a clone.
         */
        static TimeZone getDefaultRef() {
            TimeZone defaultZone = defaultTimeZone;
            if (defaultZone == null) {
                // Need to initialize the default time zone.
                defaultZone = setDefaultZone();
                assert defaultZone != null;
            }
            // Don't clone here.
            return defaultZone;
        }
    
        private static synchronized TimeZone setDefaultZone() {
            TimeZone tz;
            // get the time zone ID from the system properties
            String zoneID = AccessController.doPrivileged(
                    new GetPropertyAction("user.timezone"));
    
            // if the time zone ID is not set (yet), perform the
            // platform to Java time zone ID mapping.
            if (zoneID == null || zoneID.isEmpty()) {
                String javaHome = AccessController.doPrivileged(
                        new GetPropertyAction("java.home"));
                try {
                    zoneID = getSystemTimeZoneID(javaHome);
                    if (zoneID == null) {
                        zoneID = GMT_ID;
                    }
                } catch (NullPointerException e) {
                    zoneID = GMT_ID;
                }
            }
    
            // Get the time zone for zoneID. But not fall back to
            // "GMT" here.
            tz = getTimeZone(zoneID, false);
    
            if (tz == null) {
                // If the given zone ID is unknown in Java, try to
                // get the GMT-offset-based time zone ID,
                // a.k.a. custom time zone ID (e.g., "GMT-08:00").
                String gmtOffsetID = getSystemGMTOffsetID();
                if (gmtOffsetID != null) {
                    zoneID = gmtOffsetID;
                }
                tz = getTimeZone(zoneID, true);
            }
            assert tz != null;
    
            final String id = zoneID;
            AccessController.doPrivileged(new PrivilegedAction<Void>() {
                @Override
                    public Void run() {
                        System.setProperty("user.timezone", id);
                        return null;
                    }
                });
    
            defaultTimeZone = tz;
            return tz;
        }
    
        /**
         * Sets the {@code TimeZone} that is returned by the {@code getDefault}
         * method. {@code zone} is cached. If {@code zone} is null, the cached
         * default {@code TimeZone} is cleared. This method doesn't change the value
         * of the {@code user.timezone} property.
         *
         * @param zone the new default {@code TimeZone}, or null
         * @throws SecurityException if the security manager's {@code checkPermission}
         *                           denies {@code PropertyPermission("user.timezone",
         *                           "write")}
         * @see #getDefault
         * @see PropertyPermission
         */
        public static void setDefault(TimeZone zone)
        {
            SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                sm.checkPermission(new PropertyPermission
                                   ("user.timezone", "write"));
            }
            defaultTimeZone = zone;
        }
    
        /**
         * Returns true if this zone has the same rule and offset as another zone.
         * That is, if this zone differs only in ID, if at all.  Returns false
         * if the other zone is null.
         * @param other the <code>TimeZone</code> object to be compared with
         * @return true if the other zone is not null and is the same as this one,
         * with the possible exception of the ID
         * @since 1.2
         */
        public boolean hasSameRules(TimeZone other) {
            return other != null && getRawOffset() == other.getRawOffset() &&
                useDaylightTime() == other.useDaylightTime();
        }
    
        /**
         * Creates a copy of this <code>TimeZone</code>.
         *
         * @return a clone of this <code>TimeZone</code>
         */
        public Object clone()
        {
            try {
                TimeZone other = (TimeZone) super.clone();
                other.ID = ID;
                return other;
            } catch (CloneNotSupportedException e) {
                throw new InternalError(e);
            }
        }
    
        /**
         * The null constant as a TimeZone.
         */
        static final TimeZone NO_TIMEZONE = null;
    
        // =======================privates===============================
    
        /**
         * The string identifier of this <code>TimeZone</code>.  This is a
         * programmatic identifier used internally to look up <code>TimeZone</code>
         * objects from the system table and also to map them to their localized
         * display names.  <code>ID</code> values are unique in the system
         * table but may not be for dynamically created zones.
         * @serial
         */
        private String           ID;
        private static volatile TimeZone defaultTimeZone;
    
        static final String         GMT_ID        = "GMT";
        private static final int    GMT_ID_LENGTH = 3;
    
        // a static TimeZone we can reference if no AppContext is in place
        private static volatile TimeZone mainAppContextDefault;
    
        /**
         * Parses a custom time zone identifier and returns a corresponding zone.
         * This method doesn't support the RFC 822 time zone format. (e.g., +hhmm)
         *
         * @param id a string of the <a href="#CustomID">custom ID form</a>.
         * @return a newly created TimeZone with the given offset and
         * no daylight saving time, or null if the id cannot be parsed.
         */
        private static final TimeZone parseCustomTimeZone(String id) {
            int length;
    
            // Error if the length of id isn't long enough or id doesn't
            // start with "GMT".
            if ((length = id.length()) < (GMT_ID_LENGTH + 2) ||
                id.indexOf(GMT_ID) != 0) {
                return null;
            }
    
            ZoneInfo zi;
    
            // First, we try to find it in the cache with the given
            // id. Even the id is not normalized, the returned ZoneInfo
            // should have its normalized id.
            zi = ZoneInfoFile.getZoneInfo(id);
            if (zi != null) {
                return zi;
            }
    
            int index = GMT_ID_LENGTH;
            boolean negative = false;
            char c = id.charAt(index++);
            if (c == '-') {
                negative = true;
            } else if (c != '+') {
                return null;
            }
    
            int hours = 0;
            int num = 0;
            int countDelim = 0;
            int len = 0;
            while (index < length) {
                c = id.charAt(index++);
                if (c == ':') {
                    if (countDelim > 0) {
                        return null;
                    }
                    if (len > 2) {
                        return null;
                    }
                    hours = num;
                    countDelim++;
                    num = 0;
                    len = 0;
                    continue;
                }
                if (c < '0' || c > '9') {
                    return null;
                }
                num = num * 10 + (c - '0');
                len++;
            }
            if (index != length) {
                return null;
            }
            if (countDelim == 0) {
                if (len <= 2) {
                    hours = num;
                    num = 0;
                } else {
                    hours = num / 100;
                    num %= 100;
                }
            } else {
                if (len != 2) {
                    return null;
                }
            }
            if (hours > 23 || num > 59) {
                return null;
            }
            int gmtOffset =  (hours * 60 + num) * 60 * 1000;
    
            if (gmtOffset == 0) {
                zi = ZoneInfoFile.getZoneInfo(GMT_ID);
                if (negative) {
                    zi.setID("GMT-00:00");
                } else {
                    zi.setID("GMT+00:00");
                }
            } else {
                zi = ZoneInfoFile.getCustomTimeZone(id, negative ? -gmtOffset : gmtOffset);
            }
            return zi;
        }
    }
    
    
  • 相关阅读:
    perl 函数 左值属性
    JavaReflectionManager cannot be cast to org.hibernate.annotations.common.reflection.MetadataProvider
    org/aspectj/weaver/reflect/ReflectionWorld$ReflectionWorldException : Unsupported major.minor versio
    Element 'property' cannot have character [children], because the type's content type is element-only
    java.lang.UnsupportedClassVersionError: org/hibernate/cfg/Configuration : Unsupported major.minor v
    Caused by: org.xml.sax.SAXParseException: The prefix "aop" for element "aop:config" is not bound
    org.hibernate.ObjectNotFoundException: No row with the given identifier exists
    Caused by: java.lang.IllegalStateException: SpringJUnit4ClassRunner requires JUnit 4.12 or higher
    如何引导企业数据“价值变现”,看能源化工业的数据化管理
    如何引导企业数据“价值变现”,看能源化工业的数据化管理
  • 原文地址:https://www.cnblogs.com/ukzq/p/13648960.html
Copyright © 2011-2022 走看看