Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/util/ISO8601Utils.java

package com.fasterxml.jackson.databind.util;

import java.text.ParseException;
import java.text.ParsePosition;
import java.util.*;

/**
 * Utilities methods for manipulating dates in iso8601 format. This is much much faster and GC friendly than using SimpleDateFormat so
 * highly suitable if you (un)serialize lots of date objects.
 * 
 * Supported parse format: [yyyy-MM-dd|yyyyMMdd][T(hh:mm[:ss[.sss]]|hhmm[ss[.sss]])]?[Z|[+-]hh[:]mm]]
 * 
 * @see <a href="http://www.w3.org/TR/NOTE-datetime">this specification</a>
 */
@Deprecated // since 2.9
public class ISO8601Utils
{
    protected final static int DEF_8601_LEN = "yyyy-MM-ddThh:mm:ss.SSS+00:00".length();

    /**
     * Timezone we use for 'Z' in ISO-8601 date/time values: since 2.7
     * {@link #TIMEZONE_UTC}; with earlier versions up to 2.7 was {@link #TIMEZONE_GMT}.
     */
    private static final TimeZone TIMEZONE_Z = TimeZone.getTimeZone("UTC");

    /*
    /**********************************************************
    /* Formatting
    /**********************************************************
     */

    /**
     * Format a date into 'yyyy-MM-ddThh:mm:ssZ' (default timezone, no milliseconds precision)
     * 
     * @param date the date to format
     * @return the date formatted as 'yyyy-MM-ddThh:mm:ssZ'
     */
    public static String format(Date date) {
        return format(date, false, TIMEZONE_Z);
    }

    /**
     * Format a date into 'yyyy-MM-ddThh:mm:ss[.sss]Z' (GMT timezone)
     * 
     * @param date the date to format
     * @param millis true to include millis precision otherwise false
     * @return the date formatted as 'yyyy-MM-ddThh:mm:ss[.sss]Z'
     */
    public static String format(Date date, boolean millis) {
        return format(date, millis, TIMEZONE_Z);
    }

    @Deprecated // since 2.9
    public static String format(Date date, boolean millis, TimeZone tz) {
        return format(date, millis, tz, Locale.US);
    }

    /**
     * Format date into yyyy-MM-ddThh:mm:ss[.sss][Z|[+-]hh:mm]
     * 
     * @param date the date to format
     * @param millis true to include millis precision otherwise false
     * @param tz timezone to use for the formatting (UTC will produce 'Z')
     * @return the date formatted as yyyy-MM-ddThh:mm:ss[.sss][Z|[+-]hh:mm]
     *
     * @since 2.9
     */
    public static String format(Date date, boolean millis, TimeZone tz, Locale loc) {
        Calendar calendar = new GregorianCalendar(tz, loc);
        calendar.setTime(date);

        // estimate capacity of buffer as close as we can (yeah, that's pedantic ;)
        StringBuilder sb = new StringBuilder(30);
        sb.append(String.format(
                "%04d-%02d-%02dT%02d:%02d:%02d",
                calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH) + 1,
                calendar.get(Calendar.DAY_OF_MONTH),
                calendar.get(Calendar.HOUR_OF_DAY),
                calendar.get(Calendar.MINUTE),
                calendar.get(Calendar.SECOND)
                ));
        if (millis) {
            sb.append(String.format(".%03d", calendar.get(Calendar.MILLISECOND)));
        }

        int offset = tz.getOffset(calendar.getTimeInMillis());
        if (offset != 0) {
            int hours = Math.abs((offset / (60 * 1000)) / 60);
            int minutes = Math.abs((offset / (60 * 1000)) % 60);
            sb.append(String.format("%c%02d:%02d",
                    (offset < 0 ? '-' : '+'),
                    hours, minutes));
        } else {
            sb.append('Z');
        }
        return sb.toString();
    }

    /*
    /**********************************************************
    /* Parsing
    /**********************************************************
     */

    /**
     * Parse a date from ISO-8601 formatted string. It expects a format
     * [yyyy-MM-dd|yyyyMMdd][T(hh:mm[:ss[.sss]]|hhmm[ss[.sss]])]?[Z|[+-]hh:mm]]
     * 
     * @param date ISO string to parse in the appropriate format.
     * @param pos The position to start parsing from, updated to where parsing stopped.
     * @return the parsed date
     * @throws ParseException if the date is not in the appropriate format
     */
    public static Date parse(String date, ParsePosition pos) throws ParseException {
        Objects.requireNonNull(date);
        Exception fail = null;
        try {
            int offset = pos.getIndex();

            // extract year
            int year = parseInt(date, offset, offset += 4);
            if (checkOffset(date, offset, '-')) {
                offset += 1;
            }

            // extract month
            int month = parseInt(date, offset, offset += 2);
            if (checkOffset(date, offset, '-')) {
                offset += 1;
            }

            // extract day
            int day = parseInt(date, offset, offset += 2);
            // default time value
            int hour = 0;
            int minutes = 0;
            int seconds = 0;
            int milliseconds = 0; // always use 0 otherwise returned date will include millis of current time

            // if the value has no time component (and no time zone), we are done
            boolean hasT = checkOffset(date, offset, 'T');
            
            if (!hasT && (date.length() <= offset)) {
                Calendar calendar = new GregorianCalendar(year, month - 1, day);

                pos.setIndex(offset);
                return calendar.getTime();
            }

            if (hasT) {

                // extract hours, minutes, seconds and milliseconds
                hour = parseInt(date, offset += 1, offset += 2);
                if (checkOffset(date, offset, ':')) {
                    offset += 1;
                }

                minutes = parseInt(date, offset, offset += 2);
                if (checkOffset(date, offset, ':')) {
                    offset += 1;
                }
                // second and milliseconds can be optional
                if (date.length() > offset) {
                    char c = date.charAt(offset);
                    if (c != 'Z' && c != '+' && c != '-') {
                        seconds = parseInt(date, offset, offset += 2);
                        if (seconds > 59 && seconds < 63) seconds = 59; // truncate up to 3 leap seconds
                        // milliseconds can be optional in the format
                        if (checkOffset(date, offset, '.')) {
                            offset += 1;
                            int endOffset = indexOfNonDigit(date, offset + 1); // assume at least one digit
                            int parseEndOffset = Math.min(endOffset, offset + 3); // parse up to 3 digits
                            int fraction = parseInt(date, offset, parseEndOffset);
                            // compensate for "missing" digits
                            switch (parseEndOffset - offset) { // number of digits parsed
                            case 2:
                                milliseconds = fraction * 10;
                                break;
                            case 1:
                                milliseconds = fraction * 100;
                                break;
                            default:
                                milliseconds = fraction;
                            }
                            offset = endOffset;
                        }
                    }
                }
            }

            // extract timezone
            if (date.length() <= offset) {
                throw new IllegalArgumentException("No time zone indicator");
            }

            TimeZone timezone = null;
            char timezoneIndicator = date.charAt(offset);

            if (timezoneIndicator == 'Z') {
                timezone = TIMEZONE_Z;
                offset += 1;
            } else if (timezoneIndicator == '+' || timezoneIndicator == '-') {
                String timezoneOffset = date.substring(offset);
                offset += timezoneOffset.length();
                // 18-Jun-2015, tatu: Minor simplification, skip offset of "+0000"/"+00:00"
                if ("+0000".equals(timezoneOffset) || "+00:00".equals(timezoneOffset)) {
                    timezone = TIMEZONE_Z;
                } else {
                    // 18-Jun-2015, tatu: Looks like offsets only work from GMT, not UTC...
                    //    not sure why, but that's the way it looks. Further, Javadocs for
                    //    `java.util.TimeZone` specifically instruct use of GMT as base for
                    //    custom timezones... odd.
                    String timezoneId = "GMT" + timezoneOffset;
//                    String timezoneId = "UTC" + timezoneOffset;

                    timezone = TimeZone.getTimeZone(timezoneId);

                    String act = timezone.getID();
                    if (!act.equals(timezoneId)) {
                        /* 22-Jan-2015, tatu: Looks like canonical version has colons, but we may be given
                         *    one without. If so, don't sweat.
                         *   Yes, very inefficient. Hopefully not hit often.
                         *   If it becomes a perf problem, add 'loose' comparison instead.
                         */
                        String cleaned = act.replace(":", "");
                        if (!cleaned.equals(timezoneId)) {
                            throw new IndexOutOfBoundsException("Mismatching time zone indicator: "+timezoneId+" given, resolves to "
                                    +timezone.getID());
                        }
                    }
                }
            } else {
                throw new IndexOutOfBoundsException("Invalid time zone indicator '" + timezoneIndicator+"'");
            }

            Calendar calendar = new GregorianCalendar(timezone);
            calendar.setLenient(false);
            calendar.set(Calendar.YEAR, year);
            calendar.set(Calendar.MONTH, month - 1);
            calendar.set(Calendar.DAY_OF_MONTH, day);
            calendar.set(Calendar.HOUR_OF_DAY, hour);
            calendar.set(Calendar.MINUTE, minutes);
            calendar.set(Calendar.SECOND, seconds);
            calendar.set(Calendar.MILLISECOND, milliseconds);

            pos.setIndex(offset);
            return calendar.getTime();
            // If we get a ParseException it'll already have the right message/offset.
            // Other exception types can convert here.
        } catch (Exception e) {
            fail = e;
        }
        String input = (date == null) ? null : ('"' + date + '"');
        String msg = fail.getMessage();
        if (msg == null || msg.isEmpty()) {
            msg = "("+fail.getClass().getName()+")";
        }
        ParseException ex = new ParseException("Failed to parse date " + input + ": " + msg, pos.getIndex());
        ex.initCause(fail);
        throw ex;
    }

    /**
     * Check if the expected character exist at the given offset in the value.
     * 
     * @param value the string to check at the specified offset
     * @param offset the offset to look for the expected character
     * @param expected the expected character
     * @return true if the expected character exist at the given offset
     */
    private static boolean checkOffset(String value, int offset, char expected) {
        return (offset < value.length()) && (value.charAt(offset) == expected);
    }

    /**
     * Parse an integer located between 2 given offsets in a string
     * 
     * @param value the string to parse
     * @param beginIndex the start index for the integer in the string
     * @param endIndex the end index for the integer in the string
     * @return the int
     * @throws NumberFormatException if the value is not a number
     */
    private static int parseInt(String value, int beginIndex, int endIndex) throws NumberFormatException {
        if (beginIndex < 0 || endIndex > value.length() || beginIndex > endIndex) {
            throw new NumberFormatException(value);
        }
        // use same logic as in Integer.parseInt() but less generic we're not supporting negative values
        int i = beginIndex;
        int result = 0;
        int digit;
        if (i < endIndex) {
            digit = Character.digit(value.charAt(i++), 10);
            if (digit < 0) {
                throw new NumberFormatException("Invalid number: " + value.substring(beginIndex, endIndex));
            }
            result = -digit;
        }
        while (i < endIndex) {
            digit = Character.digit(value.charAt(i++), 10);
            if (digit < 0) {
                throw new NumberFormatException("Invalid number: " + value.substring(beginIndex, endIndex));
            }
            result *= 10;
            result -= digit;
        }
        return -result;
    }

    /**
     * Returns the index of the first character in the string that is not a digit, starting at offset.
     */
    private static int indexOfNonDigit(String string, int offset) {
        for (int i = offset; i < string.length(); i++) {
            char c = string.charAt(i);
            if (c < '0' || c > '9') return i;
        }
        return string.length();
    }
}

⏎ com/fasterxml/jackson/databind/util/ISO8601Utils.java

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File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
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