dateparser.java

用于移动设备上的java虚拟机源代码

     * @param  year The Gegorian year
     * @param  month The month
     * @param  day The day of the month <code>month</code>
     * @return the number of Julian days.
     */
    private final long computeJulianDay(int year, int month, int day) {
        int y;
        long millis = 0;
        
        boolean isLeap = year%4 == 0;
        y = year - 1;
        long julianDay = 365L*y + floorDivide(y, 4) + (JAN_1_1_JULIAN_DAY - 3);
        
        isLeap = isLeap && ((year%100 != 0) || (year%400 == 0));
        // Add 2 because Gregorian calendar starts 2 days after Julian calendar
        julianDay += floorDivide(y, 400) - floorDivide(y, 100) + 2;
        julianDay += isLeap ? LEAP_NUM_DAYS[month] : NUM_DAYS[month];
        julianDay += day;

        return julianDay;
    }

    /**
     * Divide two long integers, returning the floor of the quotient.
     * <p>
     * Unlike the built-in division, this is mathematically well-behaved.
     * E.g., <code>-1/4</code> => 0
     * but <code>floorDivide(-1,4)</code> => -1.
     * @param numerator the numerator
     * @param denominator a divisor which must be > 0
     * @return the floor of the quotient.
     */
    private static final long floorDivide(long numerator, long denominator) {
        // We do this computation in order to handle
        // a numerator of Long.MIN_VALUE correctly
        return (numerator >= 0) ?
            numerator / denominator :
            ((numerator + 1) / denominator) - 1;
    }
    
    // public String toString() {
    //  return "" + month + "/" + day + "/" + year 
    //          + " " + hour + ":" + minute + ":" + second;
    // }

    /**
     * Convert the Julian day, <code>julian</code> into milliseconds.
     *
     * @param julian   Number of days since Jan 1, year 1 (Julian).
     * @return the number of millis since the 01/01/1970.
     */
    private long julianDayToMillis(long julian) {
        return (julian - julianDayOffset) * millisPerDay;
    }
    
    /**
     * Parse the date string <code>s</code>
     *
     * @param   s   a string representation of the date.
     */
    private void internalParse(String s) {
        int year = -1;
        int mon = -1;
        int mday = -1;
        int hour = -1;
        int min = -1;
        int sec = -1;
        int millis = -1;
        int c = -1;
        int i = 0;
        int n = -1;
        int wst = -1;
        int tzoffset = -1;
        int prevc = 0;

        syntax: {
            if (s == null)
                break syntax;
            int limit = s.length();
            while (i < limit) {
                c = s.charAt(i);
                i++;
                if (c <= ' ' || c == ',')
                    continue;
                if (c == '(') { // skip comments
                    int depth = 1;
                    while (i < limit) {
                        c = s.charAt(i);
                        i++;
                        if (c == '(') depth++;
                        else if (c == ')')
                            if (--depth <= 0)
                                break;
                    }
                    continue;
                }
                if ('0' <= c && c <= '9') {
                    n = c - '0';
                    while (i < limit && '0' <= (c = s.charAt(i)) && c <= '9') {
                        n = n * 10 + c - '0';
                        i++;
                    }
                    if (prevc == '+' || prevc == '-' && year >= 0) {
                        // timezone offset
                        if (n < 24)
                            n = n * 60; // EG. "GMT-3"
                        else
                            n = n % 100 + n / 100 * 60; // eg "GMT-0430"
                        if (prevc == '+')       // plus means east of GMT
                            n = -n;
                        if (tzoffset != 0 && tzoffset != -1)
                            break syntax;
                        tzoffset = n;
                    } else if (n >= 70)
                        if (year >= 0)
                            break syntax;
                        else if (c <= ' ' || c == ',' || c == '/' || i >= limit)
                            // year = n < 1900 ? n : n - 1900;
                            year = n < 100 ? n + 1900 : n;
                        else
                            break syntax;
                    else if (c == ':')
                        if (hour < 0)
                            hour = (byte) n;
                        else if (min < 0)
                            min = (byte) n;
                        else
                            break syntax;
                    else if (c == '/')
                        if (mon < 0)
                            mon = (byte) (n - 1);
                        else if (mday < 0)
                            mday = (byte) n;
                        else
                            break syntax;
                    else if (i < limit && c != ',' && c > ' ' && c != '-')
                        break syntax;
                    else if (hour >= 0 && min < 0)
                        min = (byte) n;
                    else if (min >= 0 && sec < 0)
                        sec = (byte) n;
                    else if (mday < 0)
                        mday = (byte) n;
                    else
                        break syntax;
                    prevc = 0;
                } else if (c == '/' || c == ':' || c == '+' || c == '-')
                    prevc = c;
                else {
                    int st = i - 1;
                    while (i < limit) {
                        c = s.charAt(i);
                        if (!('A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'))
                            break;
                        i++;
                    }
                    if (i <= st + 1)
                        break syntax;
                    int k;
                    for (k = wtb.length; --k >= 0; )
                        if (wtb[k].regionMatches(true, 0, s, st, i - st)) {
                            int action = ttb[k];
                            if (action != 0) {
                                if (action == 1) {      // pm
                                    if (hour > 12 || hour < 1)
                                        break syntax;
                                    else if (hour < 12)
                                        hour += 12;
                                } else if (action == 14) {  // am
                                    if (hour > 12 || hour < 1)
                                        break syntax;
                                    else if (hour == 12)
                                        hour = 0;
                                } else if (action <= 13) {      // month!
                                    if (mon < 0)
                                        mon = (byte) (action - 2);
                                    else
                                        break syntax;
                                } else {
                                    tzoffset = action - 10000;
                                }
                            }
                            break;
                        }
                    if (k < 0)
                        break syntax;
                    prevc = 0;
                }
            }
            if (year < 1583 || mon < 0 || mday < 0)
                break syntax;
            if (sec < 0)
                sec = 0;
            if (min < 0)
                min = 0;
            if (hour < 0)
                hour = 0;
            
            this.year = year;
            month = mon;
            day = mday;
            this.hour = hour;
            this.tzoffset = -tzoffset * 60 * 1000;
            minute = min;
            second = sec;
            milli = 0;
            return;
        }
        // syntax error
        throw new IllegalArgumentException();
    }
    
    /** A table of valid timezones */
    private static Hashtable timezones;

    /** Number of days in each month in a non leap year */
    private int[] days_in_month = {31, 28, 31, 30, 31, 30, 31,
                                   31, 30, 31, 30, 31};
    /** Short versions of the month strings */
    private String[] month_shorts = {"Jan", "Feb", "Mar", "Apr", 
                                     "May", "Jun", "Jul", "Aug", 
                                     "Sep", "Oct", "Nov", "Dec"};
    /** Short versions of the weekday strings */
    private String[] weekday_shorts = {"Mon", "Tue", "Wed", "Thu",
                                       "Fri", "Sat", "Sun"};
    
    /** Offset from Jan 1, year 1 (Julian) and Jan 1, 1970 */
    private static long julianDayOffset = 2440588;
    /** Number of milliseconds per hour */
    private static int millisPerHour = 60 * 60 * 1000;
    /** Number of milliseconds per day */
    private static int millisPerDay = 24 * millisPerHour;
    /** Jan 1, year 1 (Gregorian) */
    private static final int JAN_1_1_JULIAN_DAY = 1721426;
    
    /** All of the valid strings for the date */
    private final static String wtb[] = {
        "am", "pm",
        "monday", "tuesday", "wednesday", "thursday", "friday",
        "saturday", "sunday",
        "january", "february", "march", "april", "may", "june",
        "july", "august", "september", "october", "november", "december",
        "gmt", "ut", "utc", "est", "edt", "cst", "cdt",
        "mst", "mdt", "pst", "pdt"
        // this time zone table needs to be expanded
    };

    /**
     * Used to process date strings. Each value coresponds to a string
     * in the wtb variable.
     */
    private final static int ttb[] = {
        14, 1, 0, 0, 0, 0, 0, 0, 0,
        2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
        10000 + 0, 10000 + 0, 10000 + 0,        // GMT/UT/UTC
        10000 + 5 * 60, 10000 + 4 * 60, // EST/EDT
        10000 + 6 * 60, 10000 + 5 * 60,
        10000 + 7 * 60, 10000 + 6 * 60,
        10000 + 8 * 60, 10000 + 7 * 60
    };
    
    /** Cummulative number of days for each month in a non leap year. */
    private static final int NUM_DAYS[]      = {  0,  31,  59,  90, 120, 151, 
                                                 181, 212, 243, 273, 304, 334};

    /** Cummulative number of days for each month in a leap year. */
    private static final int LEAP_NUM_DAYS[] = {  0,  31,  60,  91, 121, 152,
                                                182, 213, 244, 274, 305, 335};
    
    static {
        timezones = new Hashtable();
        timezones.put("GMT", new Integer(0 * millisPerHour));
        timezones.put("UT", new Integer(0 * millisPerHour));
        timezones.put("UTC", new Integer(0 * millisPerHour));
        timezones.put("PST", new Integer(-8 * millisPerHour));
        timezones.put("PDT", new Integer(-7 * millisPerHour));
        timezones.put("JST", new Integer(9 * millisPerHour));
        
        local_tz = ((Integer)timezones.get("PST")).intValue();
    }
}