Java tutorial
package com.fasterxml.jackson.databind.util; 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. */ public class ISO8601Utils { /** * ID to represent the 'GMT' string */ private static final String GMT_ID = "GMT"; /** * The GMT timezone */ private static final TimeZone TIMEZONE_GMT = TimeZone.getTimeZone(GMT_ID); /* /********************************************************** /* Static factories /********************************************************** */ /** * Accessor for static GMT timezone instance. */ public static TimeZone timeZoneGMT() { return TIMEZONE_GMT; } /* /********************************************************** /* Formatting /********************************************************** */ /** * Format a date into 'yyyy-MM-ddThh:mm:ssZ' (GMT 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_GMT); } /** * 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_GMT); } /** * 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 (GMT will produce 'Z') * @return the date formatted as yyyy-MM-ddThh:mm:ss[.sss][Z|[+-]hh:mm] */ public static String format(Date date, boolean millis, TimeZone tz) { Calendar calendar = new GregorianCalendar(tz, Locale.US); calendar.setTime(date); // estimate capacity of buffer as close as we can (yeah, that's pedantic ;) int capacity = "yyyy-MM-ddThh:mm:ss".length(); capacity += millis ? ".sss".length() : 0; capacity += tz.getRawOffset() == 0 ? "Z".length() : "+hh:mm".length(); StringBuilder formatted = new StringBuilder(capacity); padInt(formatted, calendar.get(Calendar.YEAR), "yyyy".length()); formatted.append('-'); padInt(formatted, calendar.get(Calendar.MONTH) + 1, "MM".length()); formatted.append('-'); padInt(formatted, calendar.get(Calendar.DAY_OF_MONTH), "dd".length()); formatted.append('T'); padInt(formatted, calendar.get(Calendar.HOUR_OF_DAY), "hh".length()); formatted.append(':'); padInt(formatted, calendar.get(Calendar.MINUTE), "mm".length()); formatted.append(':'); padInt(formatted, calendar.get(Calendar.SECOND), "ss".length()); if (millis) { formatted.append('.'); padInt(formatted, calendar.get(Calendar.MILLISECOND), "sss".length()); } 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); formatted.append(offset < 0 ? '-' : '+'); padInt(formatted, hours, "hh".length()); formatted.append(':'); padInt(formatted, minutes, "mm".length()); } else { formatted.append('Z'); } return formatted.toString(); } /* /********************************************************** /* Parsing /********************************************************** */ /** * Parse a date from ISO-8601 formatted string. It expects a format yyyy-MM-ddThh:mm:ss[.sss][Z|[+-]hh:mm] * * @param date ISO string to parse in the appropriate format. * @return the parsed date * @throws IllegalArgumentException if the date is not in the appropriate format */ public static Date parse(String date) { Exception fail = null; try { int offset = 0; // extract year int year = parseInt(date, offset, offset += 4); checkOffset(date, offset, '-'); // extract month int month = parseInt(date, offset += 1, offset += 2); checkOffset(date, offset, '-'); // extract day int day = parseInt(date, offset += 1, offset += 2); checkOffset(date, offset, 'T'); // extract hours, minutes, seconds and milliseconds int hour = parseInt(date, offset += 1, offset += 2); checkOffset(date, offset, ':'); int minutes = parseInt(date, offset += 1, offset += 2); checkOffset(date, offset, ':'); int seconds = parseInt(date, offset += 1, offset += 2); // milliseconds can be optional in the format int milliseconds = 0; // always use 0 otherwise returned date will include millis of current time if (date.charAt(offset) == '.') { checkOffset(date, offset, '.'); milliseconds = parseInt(date, offset += 1, offset += 3); } // extract timezone String timezoneId; char timezoneIndicator = date.charAt(offset); if (timezoneIndicator == '+' || timezoneIndicator == '-') { timezoneId = GMT_ID + date.substring(offset); } else if (timezoneIndicator == 'Z') { timezoneId = GMT_ID; } else { throw new IndexOutOfBoundsException("Invalid time zone indicator " + timezoneIndicator); } TimeZone timezone = TimeZone.getTimeZone(timezoneId); if (!timezone.getID().equals(timezoneId)) { throw new IndexOutOfBoundsException(); } 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); return calendar.getTime(); } catch (IndexOutOfBoundsException e) { fail = e; } catch (NumberFormatException e) { fail = e; } catch (IllegalArgumentException e) { fail = e; } String input = (date == null) ? null : ('"' + date + "'"); throw new IllegalArgumentException("Failed to parse date [" + input + "]: " + fail.getMessage(), fail); } /** * Check if the expected character exist at the given offset of the * * @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 * @throws IndexOutOfBoundsException if the expected character is not found */ private static void checkOffset(String value, int offset, char expected) throws IndexOutOfBoundsException { char found = value.charAt(offset); if (found != expected) { throw new IndexOutOfBoundsException("Expected '" + expected + "' character but found '" + found + "'"); } } /** * 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); } result = -digit; } while (i < endIndex) { digit = Character.digit(value.charAt(i++), 10); if (digit < 0) { throw new NumberFormatException("Invalid number: " + value); } result *= 10; result -= digit; } return -result; } /** * Zero pad a number to a specified length * * @param buffer buffer to use for padding * @param value the integer value to pad if necessary. * @param length the length of the string we should zero pad */ private static void padInt(StringBuilder buffer, int value, int length) { String strValue = Integer.toString(value); for (int i = length - strValue.length(); i > 0; i--) { buffer.append('0'); } buffer.append(strValue); } }