ISO8601Utils.java
/*
* Copyright (C) 2015 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.gson.internal.bind.util;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
/**
* Utilities methods for manipulating dates in iso8601 format. This is much faster and GC friendly
* than using SimpleDateFormat so highly suitable if you (un)serialize lots of date objects.
*
* <p>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>
*/
// Date parsing code from Jackson databind ISO8601Utils.java
// https://github.com/FasterXML/jackson-databind/blob/2.8/src/main/java/com/fasterxml/jackson/databind/util/ISO8601Utils.java
public class ISO8601Utils {
private ISO8601Utils() {}
/**
* ID to represent the 'UTC' string, default timezone since Jackson 2.7
*
* @since 2.7
*/
private static final String UTC_ID = "UTC";
/**
* The UTC timezone, prefetched to avoid more lookups.
*
* @since 2.7
*/
private static final TimeZone TIMEZONE_UTC = TimeZone.getTimeZone(UTC_ID);
/*
/**********************************************************
/* 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_UTC);
}
/**
* 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_UTC);
}
/**
* 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]
*/
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-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 {
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;
// always use 0 otherwise returned date will include millis of current time
int milliseconds = 0;
// 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);
calendar.setLenient(false);
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_UTC;
offset += 1;
} else if (timezoneIndicator == '+' || timezoneIndicator == '-') {
String timezoneOffset = date.substring(offset);
// When timezone has no minutes, we should append it, valid timezones are, for example:
// +00:00, +0000 and +00
timezoneOffset = timezoneOffset.length() >= 5 ? timezoneOffset : timezoneOffset + "00";
offset += timezoneOffset.length();
// 18-Jun-2015, tatu: Minor simplification, skip offset of "+0000"/"+00:00"
if (timezoneOffset.equals("+0000") || timezoneOffset.equals("+00:00")) {
timezone = TIMEZONE_UTC;
} 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 (IndexOutOfBoundsException | IllegalArgumentException 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;
}
/**
* 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);
}
/**
* 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();
}
}