package co.codewizards.cloudstore.core.util;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
/**
* The <code>ISO8601</code> utility class provides helper methods
* to deal with date/time formatting using a specific ISO8601-compliant
* format (see <a href="http://www.w3.org/TR/NOTE-datetime">ISO 8601</a>).
* <p/>
* The currently supported format is:
* <pre>
* ±YYYY-MM-DDThh:mm:ss.SSSTZD
* </pre>
* where:
* <pre>
* ±YYYY = four-digit year with optional sign where values <= 0 are
* denoting years BCE and values > 0 are denoting years CE,
* e.g. -0001 denotes the year 2 BCE, 0000 denotes the year 1 BCE,
* 0001 denotes the year 1 CE, and so on...
* MM = two-digit month (01=January, etc.)
* DD = two-digit day of month (01 through 31)
* hh = two digits of hour (00 through 23) (am/pm NOT allowed)
* mm = two digits of minute (00 through 59)
* ss = two digits of second (00 through 59)
* SSS = three digits of milliseconds (000 through 999)
* TZD = time zone designator, Z for Zulu (i.e. UTC) or an offset from UTC
* in the form of +hh:mm or -hh:mm
* </pre>
* <p>
* This class was copied from the
* <a href="http://svn.apache.org/repos/asf/jackrabbit/trunk/jackrabbit-jcr-tests/src/main/java/org/apache/jackrabbit/test/ISO8601.java">Apache SVN</a>.
* It is free software under the Apache Licence.
*/
public final class ISO8601 {
/**
* Convenience method calling {@link #parse(String)} and converting the
* result to a {@link Date}.
* @param text the text to be parsed. Must not be <code>null</code>.
* @return the parsed {@link Date}. Never <code>null</code>.
*/
public static Date parseDate(String text) {
Calendar calendar = parse(text);
return calendar.getTime();
}
/**
* Convenience method calling {@link #format(Calendar)} with a UTC
* time zone (as a {@link Date} does not have a time zone by definition).
*/
public static String formatDate(Date date) throws IllegalArgumentException {
if (date == null) {
throw new IllegalArgumentException("argument can not be null");
}
Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.UK);
calendar.setTime(date);
return format(calendar);
}
/**
* Parses an ISO8601-compliant date/time string.
*
* @param text the date/time string to be parsed
* @return a <code>Calendar</code>, or <code>null</code> if the input could
* not be parsed
* @throws IllegalArgumentException if a <code>null</code> argument is passed
*/
public static Calendar parse(String text) {
if (text == null) {
throw new IllegalArgumentException("argument can not be null");
}
// check optional leading sign
char sign;
int start;
if (text.startsWith("-")) {
sign = '-';
start = 1;
} else if (text.startsWith("+")) {
sign = '+';
start = 1;
} else {
sign = '+'; // no sign specified, implied '+'
start = 0;
}
/**
* the expected format of the remainder of the string is:
* YYYY-MM-DDThh:mm:ss.SSSTZD
*
* note that we cannot use java.text.SimpleDateFormat for
* parsing because it can't handle years <= 0 and TZD's
*/
int year, month, day, hour, min, sec, ms;
String tzID;
try {
// year (YYYY)
year = Integer.parseInt(text.substring(start, start + 4));
start += 4;
// delimiter '-'
if (text.charAt(start) != '-') {
return null;
}
start++;
// month (MM)
month = Integer.parseInt(text.substring(start, start + 2));
start += 2;
// delimiter '-'
if (text.charAt(start) != '-') {
return null;
}
start++;
// day (DD)
day = Integer.parseInt(text.substring(start, start + 2));
start += 2;
// delimiter 'T'
if (text.charAt(start) != 'T') {
return null;
}
start++;
// hour (hh)
hour = Integer.parseInt(text.substring(start, start + 2));
start += 2;
// delimiter ':'
if (text.charAt(start) != ':') {
return null;
}
start++;
// minute (mm)
min = Integer.parseInt(text.substring(start, start + 2));
start += 2;
// delimiter ':'
if (text.charAt(start) != ':') {
return null;
}
start++;
// second (ss)
sec = Integer.parseInt(text.substring(start, start + 2));
start += 2;
// delimiter '.'
if (text.charAt(start) != '.') {
return null;
}
start++;
// millisecond (SSS)
ms = Integer.parseInt(text.substring(start, start + 3));
start += 3;
// time zone designator (Z or +00:00 or -00:00)
if (text.charAt(start) == '+' || text.charAt(start) == '-') {
// offset to UTC specified in the format +00:00/-00:00
tzID = "GMT" + text.substring(start);
} else if (text.substring(start).equals("Z")) {
tzID = "GMT";
} else {
// invalid time zone designator
return null;
}
} catch (IndexOutOfBoundsException e) {
return null;
} catch (NumberFormatException e) {
return null;
}
TimeZone tz = TimeZone.getTimeZone(tzID);
// verify id of returned time zone (getTimeZone defaults to "GMT")
if (!tz.getID().equals(tzID)) {
// invalid time zone
return null;
}
// initialize Calendar object
Calendar cal = Calendar.getInstance(tz);
cal.setLenient(false);
// year and era
if (sign == '-' || year == 0) {
// not CE, need to set era (BCE) and adjust year
cal.set(Calendar.YEAR, year + 1);
cal.set(Calendar.ERA, GregorianCalendar.BC);
} else {
cal.set(Calendar.YEAR, year);
cal.set(Calendar.ERA, GregorianCalendar.AD);
}
// month (0-based!)
cal.set(Calendar.MONTH, month - 1);
// day of month
cal.set(Calendar.DAY_OF_MONTH, day);
// hour
cal.set(Calendar.HOUR_OF_DAY, hour);
// minute
cal.set(Calendar.MINUTE, min);
// second
cal.set(Calendar.SECOND, sec);
// millisecond
cal.set(Calendar.MILLISECOND, ms);
try {
/**
* the following call will trigger an IllegalArgumentException
* if any of the set values are illegal or out of range
*/
cal.getTime();
/**
* in addition check the validity of the year
*/
getYear(cal);
} catch (IllegalArgumentException e) {
return null;
}
return cal;
}
/**
* Formats a <code>Calendar</code> value into an ISO8601-compliant
* date/time string.
*
* @param cal the time value to be formatted into a date/time string.
* @return the formatted date/time string.
* @throws IllegalArgumentException if a <code>null</code> argument is passed
* or the calendar cannot be represented as defined by ISO 8601 (i.e. year
* with more than four digits).
*/
public static String format(Calendar cal) throws IllegalArgumentException {
if (cal == null) {
throw new IllegalArgumentException("argument can not be null");
}
/**
* the format of the date/time string is:
* YYYY-MM-DDThh:mm:ss.SSSTZD
*
* note that we cannot use java.text.SimpleDateFormat for
* formatting because it can't handle years <= 0 and TZD's
*/
StringBuilder buf = new StringBuilder();
// year ([-]YYYY)
appendZeroPaddedInt(buf, getYear(cal), 4);
buf.append('-');
// month (MM)
appendZeroPaddedInt(buf, cal.get(Calendar.MONTH) + 1, 2);
buf.append('-');
// day (DD)
appendZeroPaddedInt(buf, cal.get(Calendar.DAY_OF_MONTH), 2);
buf.append('T');
// hour (hh)
appendZeroPaddedInt(buf, cal.get(Calendar.HOUR_OF_DAY), 2);
buf.append(':');
// minute (mm)
appendZeroPaddedInt(buf, cal.get(Calendar.MINUTE), 2);
buf.append(':');
// second (ss)
appendZeroPaddedInt(buf, cal.get(Calendar.SECOND), 2);
buf.append('.');
// millisecond (SSS)
appendZeroPaddedInt(buf, cal.get(Calendar.MILLISECOND), 3);
// time zone designator (Z or +00:00 or -00:00)
TimeZone tz = cal.getTimeZone();
// determine offset of timezone from UTC (incl. daylight saving)
int offset = tz.getOffset(cal.getTimeInMillis());
if (offset != 0) {
int hours = Math.abs((offset / (60 * 1000)) / 60);
int minutes = Math.abs((offset / (60 * 1000)) % 60);
buf.append(offset < 0 ? '-' : '+');
appendZeroPaddedInt(buf, hours, 2);
buf.append(':');
appendZeroPaddedInt(buf, minutes, 2);
} else {
buf.append('Z');
}
return buf.toString();
}
/**
* Returns the astronomical year of the given calendar.
*
* @param cal a calendar instance.
* @return the astronomical year.
* @throws IllegalArgumentException if calendar cannot be represented as
* defined by ISO 8601 (i.e. year with more
* than four digits).
*/
public static int getYear(Calendar cal) throws IllegalArgumentException {
// determine era and adjust year if necessary
int year = cal.get(Calendar.YEAR);
if (cal.isSet(Calendar.ERA)
&& cal.get(Calendar.ERA) == GregorianCalendar.BC) {
/**
* calculate year using astronomical system:
* year n BCE => astronomical year -n + 1
*/
year = 0 - year + 1;
}
if (year > 9999 || year < -9999) {
throw new IllegalArgumentException("Calendar has more than four " +
"year digits, cannot be formatted as ISO8601: " + year);
}
return year;
}
/**
* Appends a zero-padded number to the given string buffer.
* <p/>
* This is an internal helper method which doesn't perform any
* validation on the given arguments.
*
* @param buf String buffer to append to
* @param n number to append
* @param precision number of digits to append
*/
private static void appendZeroPaddedInt(StringBuilder buf, int n, int precision) {
if (n < 0) {
buf.append('-');
n = -n;
}
for (int exp = precision - 1; exp > 0; exp--) {
if (n < Math.pow(10, exp)) {
buf.append('0');
} else {
break;
}
}
buf.append(n);
}
}