simpletimezone.java

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     * <dt><code>DOW_GE_DOM_MODE</code></dt>
     * <dd>
     * Day of week after day of month; e.g., Sunday on or after March 15.
     * </dd>
     * <dt><code>DOW_LE_DOM_MODE</code></dt>
     * <dd>
     * Day of week before day of month; e.g., Sunday on or before March 15.
     * </dd>
     * </dl>
     * The setting of this field affects the interpretation of the
     * <code>endDay</code> field.
     * <p>If <code>useDaylight</code> is false, this value is ignored.
     * @serial
     * @since 1.1.4
     */
    private int endMode;

    /**
     * A positive value indicating the amount of time saved during DST in
     * milliseconds.
     * Typically one hour (3600000); sometimes 30 minutes (1800000).
     * <p>If <code>useDaylight</code> is false, this value is ignored.
     * @serial
     * @since 1.1.4
     */
    private int dstSavings;

    /**
     * Constants specifying values of startMode and endMode.
     */
    private static final int DOM_MODE          = 1; // Exact day of month, "Mar 1"
    private static final int DOW_IN_MONTH_MODE = 2; // Day of week in month, "lastSun"
    private static final int DOW_GE_DOM_MODE   = 3; // Day of week after day of month, "Sun>=15"
    private static final int DOW_LE_DOM_MODE   = 4; // Day of week before day of month, "Sun<=21"

    /**
     * Constant for a mode of start or end time specified as wall clock
     * time.  Wall clock time is standard time for the onset rule, and
     * daylight time for the end rule.
     * @since 1.4
     */
    public static final int WALL_TIME = 0; // Zero for backward compatibility

    /**
     * Constant for a mode of start or end time specified as standard time.
     * @since 1.4
     */
    public static final int STANDARD_TIME = 1;

    /**
     * Constant for a mode of start or end time specified as UTC. European
     * Union rules are specified as UTC time, for example.
     * @since 1.4
     */
    public static final int UTC_TIME = 2;

    // Proclaim compatibility with 1.1
    static final long serialVersionUID = -403250971215465050L;

    // the internal serial version which says which version was written
    // - 0 (default) for version up to JDK 1.1.3
    // - 1 for version from JDK 1.1.4, which includes 3 new fields
    // - 2 for JDK 1.3, which includes 2 new fields
    static final int currentSerialVersion = 2;

    /**
     * The version of the serialized data on the stream.  Possible values:
     * <dl>
     * <dt><b>0</b> or not present on stream</dt>
     * <dd>
     * JDK 1.1.3 or earlier.
     * </dd>
     * <dt><b>1</b></dt>
     * <dd>
     * JDK 1.1.4 or later.  Includes three new fields: <code>startMode</code>,
     * <code>endMode</code>, and <code>dstSavings</code>.
     * </dd>
     * <dt><b>2</b></dt>
     * <dd>
     * JDK 1.3 or later.  Includes two new fields: <code>startTimeMode</code>
     * and <code>endTimeMode</code>.
     * </dd>
     * </dl>
     * When streaming out this class, the most recent format
     * and the highest allowable <code>serialVersionOnStream</code>
     * is written.
     * @serial
     * @since 1.1.4
     */
    private int serialVersionOnStream = currentSerialVersion;

    //----------------------------------------------------------------------
    // Rule representation
    //
    // We represent the following flavors of rules:
    //       5        the fifth of the month
    //       lastSun  the last Sunday in the month
    //       lastMon  the last Monday in the month
    //       Sun>=8   first Sunday on or after the eighth
    //       Sun<=25  last Sunday on or before the 25th
    // This is further complicated by the fact that we need to remain
    // backward compatible with the 1.1 FCS.  Finally, we need to minimize
    // API changes.  In order to satisfy these requirements, we support
    // three representation systems, and we translate between them.
    //
    // INTERNAL REPRESENTATION
    // This is the format SimpleTimeZone objects take after construction or
    // streaming in is complete.  Rules are represented directly, using an
    // unencoded format.  We will discuss the start rule only below; the end
    // rule is analogous.
    //   startMode      Takes on enumerated values DAY_OF_MONTH,
    //                  DOW_IN_MONTH, DOW_AFTER_DOM, or DOW_BEFORE_DOM.
    //   startDay       The day of the month, or for DOW_IN_MONTH mode, a
    //                  value indicating which DOW, such as +1 for first,
    //                  +2 for second, -1 for last, etc.
    //   startDayOfWeek The day of the week.  Ignored for DAY_OF_MONTH.
    //
    // ENCODED REPRESENTATION
    // This is the format accepted by the constructor and by setStartRule()
    // and setEndRule().  It uses various combinations of positive, negative,
    // and zero values to encode the different rules.  This representation
    // allows us to specify all the different rule flavors without altering
    // the API.
    //   MODE              startMonth    startDay    startDayOfWeek
    //   DOW_IN_MONTH_MODE >=0           !=0         >0
    //   DOM_MODE          >=0           >0          ==0
    //   DOW_GE_DOM_MODE   >=0           >0          <0
    //   DOW_LE_DOM_MODE   >=0           <0          <0
    //   (no DST)          don't care    ==0         don't care
    //
    // STREAMED REPRESENTATION
    // We must retain binary compatibility with the 1.1 FCS.  The 1.1 code only
    // handles DOW_IN_MONTH_MODE and non-DST mode, the latter indicated by the
    // flag useDaylight.  When we stream an object out, we translate into an
    // approximate DOW_IN_MONTH_MODE representation so the object can be parsed
    // and used by 1.1 code.  Following that, we write out the full
    // representation separately so that contemporary code can recognize and
    // parse it.  The full representation is written in a "packed" format,
    // consisting of a version number, a length, and an array of bytes.  Future
    // versions of this class may specify different versions.  If they wish to
    // include additional data, they should do so by storing them after the
    // packed representation below.
    //----------------------------------------------------------------------

    /**
     * Given a set of encoded rules in startDay and startDayOfMonth, decode
     * them and set the startMode appropriately.  Do the same for endDay and
     * endDayOfMonth.  Upon entry, the day of week variables may be zero or
     * negative, in order to indicate special modes.  The day of month
     * variables may also be negative.  Upon exit, the mode variables will be
     * set, and the day of week and day of month variables will be positive.
     * This method also recognizes a startDay or endDay of zero as indicating
     * no DST.
     */
    private void decodeRules()
    {
        decodeStartRule();
        decodeEndRule();
    }

    /**
     * Decode the start rule and validate the parameters.  The parameters are
     * expected to be in encoded form, which represents the various rule modes
     * by negating or zeroing certain values.  Representation formats are:
     * <p>
     * <pre>
     *            DOW_IN_MONTH  DOM    DOW>=DOM  DOW<=DOM  no DST
     *            ------------  -----  --------  --------  ----------
     * month       0..11        same    same      same     don't care
     * day        -5..5         1..31   1..31    -1..-31   0
     * dayOfWeek   1..7         0      -1..-7    -1..-7    don't care
     * time        0..ONEDAY    same    same      same     don't care
     * </pre>
     * The range for month does not include UNDECIMBER since this class is
     * really specific to GregorianCalendar, which does not use that month.
     * The range for time includes ONEDAY (vs. ending at ONEDAY-1) because the
     * end rule is an exclusive limit point.  That is, the range of times that
     * are in DST include those >= the start and < the end.  For this reason,
     * it should be possible to specify an end of ONEDAY in order to include the
     * entire day.  Although this is equivalent to time 0 of the following day,
     * it's not always possible to specify that, for example, on December 31.
     * While arguably the start range should still be 0..ONEDAY-1, we keep
     * the start and end ranges the same for consistency.
     */
    private void decodeStartRule() {
        useDaylight = (startDay != 0) && (endDay != 0);
        if (startDay != 0) {
            if (startMonth < Calendar.JANUARY || startMonth > Calendar.DECEMBER) {
                throw new IllegalArgumentException(
                        "Illegal start month " + startMonth);
            }
            if (startTime < 0 || startTime >= millisPerDay) {
                throw new IllegalArgumentException(
                        "Illegal start time " + startTime);
            }
            if (startDayOfWeek == 0) {
                startMode = DOM_MODE;
            } else {
                if (startDayOfWeek > 0) {
                    startMode = DOW_IN_MONTH_MODE;
                } else {
                    startDayOfWeek = -startDayOfWeek;
                    if (startDay > 0) {
                        startMode = DOW_GE_DOM_MODE;
                    } else {
                        startDay = -startDay;
                        startMode = DOW_LE_DOM_MODE;
                    }
                }
                if (startDayOfWeek > Calendar.SATURDAY) {
                    throw new IllegalArgumentException(
                           "Illegal start day of week " + startDayOfWeek);
                }
            }
            if (startMode == DOW_IN_MONTH_MODE) {
                if (startDay < -5 || startDay > 5) {
                    throw new IllegalArgumentException(
                            "Illegal start day of week in month " + startDay);
                }
            } else if (startDay < 1 || startDay > staticMonthLength[startMonth]) {
                throw new IllegalArgumentException(
                        "Illegal start day " + startDay);
            }
        }
    }

    /**
     * Decode the end rule and validate the parameters.  This method is exactly
     * analogous to decodeStartRule().
     * @see decodeStartRule
     */
    private void decodeEndRule() {
        useDaylight = (startDay != 0) && (endDay != 0);
        if (endDay != 0) {
            if (endMonth < Calendar.JANUARY || endMonth > Calendar.DECEMBER) {
                throw new IllegalArgumentException(
                        "Illegal end month " + endMonth);
            }
            if (endTime < 0 || endTime >= millisPerDay) {
                throw new IllegalArgumentException(
                        "Illegal end time " + endTime);
            }
            if (endDayOfWeek == 0) {
                endMode = DOM_MODE;
            } else {
                if (endDayOfWeek > 0) {
                    endMode = DOW_IN_MONTH_MODE;
                } else {
                    endDayOfWeek = -endDayOfWeek;
                    if (endDay > 0) {
                        endMode = DOW_GE_DOM_MODE;
                    } else {
                        endDay = -endDay;
                        endMode = DOW_LE_DOM_MODE;
                    }
                }
                if (endDayOfWeek > Calendar.SATURDAY) {
                    throw new IllegalArgumentException(
                           "Illegal end day of week " + endDayOfWeek);
                }
            }
            if (endMode == DOW_IN_MONTH_MODE) {
                if (endDay < -5 || endDay > 5) {
                    throw new IllegalArgumentException(
                            "Illegal end day of week in month " + endDay);
                }
            } else if (endDay < 1 || endDay > staticMonthLength[endMonth]) {
                throw new IllegalArgumentException(
                        "Illegal end day " + endDay);
            }
        }
    }

    /**
     * Make rules compatible to 1.1 FCS code.  Since 1.1 FCS code only understands
     * day-of-week-in-month rules, we must modify other modes of rules to their
     * approximate equivalent in 1.1 FCS terms.  This method is used when streaming
     * out objects of this class.  After it is called, the rules will be modified,
     * with a possible loss of information.  startMode and endMode will NOT be
     * altered, even though semantically they should be set to DOW_IN_MONTH_MODE,
     * since the rule modification is only intended to be temporary.
     */
    private void makeRulesCompatible()
    {
        switch (startMode) {
        case DOM_MODE:
            startDay = 1 + (startDay / 7);
            startDayOfWeek = Calendar.SUNDAY;
            break;

        case DOW_GE_DOM_MODE:
            // A day-of-month of 1 is equivalent to DOW_IN_MONTH_MODE
            // that is, Sun>=1 == firstSun.
            if (startDay != 1) {
                startDay = 1 + (startDay / 7);
	    }
            break;

        case DOW_LE_DOM_MODE:
            if (startDay >= 30) {