Java Calendar Calculate decode(String timestamp, Calendar calendar)

Description

Converts a DSA encoded timestamp into a Java Calendar.

License

Apache License

Parameter

Parameter	Description
timestamp	The encoded timestamp.
calendar	The instance to decode into and returnt, may be null. If the timestamp does not specify a timezone, the zone in this instance will be used.

Declaration

public static Calendar decode(String timestamp, Calendar calendar) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.util.*;

public class Main {
    public static final int MILLIS_MINUTE = 60 * 1000;
    public static final int MILLIS_HOUR = 60 * MILLIS_MINUTE;
    private static final Map<String, TimeZone> timezones = new HashMap<String, TimeZone>();

    /**//from   w w  w .j a  v a  2s  .  c  o m
     * Converts a DSA encoded timestamp into a Java Calendar.  DSA encoding is based
     * on ISO 8601 but allows for an unspecified timezone.
     * @param timestamp The encoded timestamp.
     * @param calendar The instance to decode into and returnt, may be null.  If the timestamp does
     *                 not specify a timezone, the zone in this instance will be used.
     */
    public static Calendar decode(String timestamp, Calendar calendar) {
        if (calendar == null) {
            calendar = Calendar.getInstance();
        }
        try {
            char[] chars = timestamp.toCharArray();
            int idx = 0;
            int year = convertDigits(chars[idx++], chars[idx++], chars[idx++], chars[idx++]);
            validateChar(chars[idx++], '-');
            int month = convertDigits(chars[idx++], chars[idx++]) - 1;
            validateChar(chars[idx++], '-');
            int day = convertDigits(chars[idx++], chars[idx++]);
            validateChar(chars[idx++], 'T');
            int hour = convertDigits(chars[idx++], chars[idx++]);
            validateChar(chars[idx++], ':');
            int minute = convertDigits(chars[idx++], chars[idx++]);
            validateChar(chars[idx++], ':');
            int second = convertDigits(chars[idx++], chars[idx++]);
            int millis = 0;
            if ((chars.length > idx) && (chars[idx] == '.')) {
                idx++;
                millis = convertDigits('0', chars[idx++], chars[idx++], chars[idx++]);
            }
            // timezone offset sign
            if (idx < chars.length) {
                char sign = chars[idx++];
                if (sign == 'Z') {
                    calendar.setTimeZone(TimeZone.getTimeZone("GMT"));
                } else {
                    int tzOff;
                    if (sign != '+' && sign != '-')
                        throw new Exception();
                    int hrOff = convertDigits(chars[idx++], chars[idx++]);
                    int minOff = 0;
                    //minutes are optional in 8601
                    if (idx < chars.length) { //minutes optional
                        validateChar(chars[idx++], ':');
                        minOff = convertDigits(chars[idx++], chars[idx++]);
                    }
                    tzOff = (hrOff * MILLIS_HOUR) + (minOff * MILLIS_MINUTE);
                    if (sign == '-')
                        tzOff *= -1;
                    String timeZoneName = "Offset" + tzOff;
                    synchronized (timezones) {
                        TimeZone timezone = timezones.get(timeZoneName);
                        if (timezone == null) {
                            timezone = new SimpleTimeZone(tzOff, timeZoneName);
                            timezones.put(timeZoneName, timezone);
                            calendar.setTimeZone(timezone);
                        }
                    }
                }
            }
            calendar.set(year, month, day, hour, minute, second);
            calendar.set(Calendar.MILLISECOND, millis);
        } catch (Exception x) {
            throw new IllegalArgumentException("Invalid timestamp: " + timestamp);
        }
        return calendar;
    }

    /**
     * Converts the characters into an int.
     */
    private static int convertDigits(char tens, char ones) {
        return (toDigit(tens) * 10) + toDigit(ones);
    }

    /**
     * Converts the characters into an int.
     */
    private static int convertDigits(char thousands, char hundreds, char tens, char ones) {
        return toDigit(thousands) * 1000 + toDigit(hundreds) * 100 + toDigit(tens) * 10 + toDigit(ones);
    }

    /**
     * Used for decoding timestamp, throws an IllegalStateException if the two characters are
     * not equal.
     */
    private static void validateChar(char c1, char c2) {
        if (c1 != c2)
            throw new IllegalStateException();
    }

    /**
     * Converts the character to a digit, throws an IllegalStateException if it isn't a
     * valid digit.
     */
    private static int toDigit(char ch) {
        if (('0' <= ch) && (ch <= '9')) {
            return ch - '0';
        }
        throw new IllegalStateException();
    }
}

Related

1. calculateWeeksInBetween(Calendar startPoint, Calendar endPoint)
2. calDateOnly(Calendar iniCal)
3. calendarIterator(final int iterateType, final Calendar startCal, final Calendar endCal)
4. cloneCalendar(Calendar in)
5. copyCalendar(final Calendar calendar, final boolean stripTime)
6. encode(Calendar calendar, boolean encodeTzOffset, StringBuilder buf)
7. equals(Calendar calendar1, Calendar calendar2)
8. FormatTime(Calendar p_time, boolean p_showMilliseconds)
9. getCalendar(long millis)