/**
* Converts this <code>Date</code> object to a <code>String</code>. The output format is as
* follows:
*
* <blockquote>
*
* <pre>yyyy MM dd hh mm ss +zzzz</pre>
*
* </blockquote>
*
* where:
*
* <ul>
* <li>
* <dd>yyyy is the year, as four decimal digits. Year values larger than
* <dd>9999 will be truncated to
* <dd>9999.
* <li>
* <dd>MM is the month (
* <dd>01 through
* <dd>12), as two decimal digits.
* <li>
* <dd>dd is the day of the month (
* <dd>01 through
* <dd>31), as two decimal digits.
* <li>
* <dd>hh is the hour of the day (
* <dd>00 through
* <dd>23), as two decimal digits.
* <li>
* <dd>mm is the minute within the hour (
* <dd>00 through
* <dd>59), as two decimal digits.
* <li>
* <dd>ss is the second within the minute (
* <dd>00 through
* <dd>59), as two decimal digits.
* <li>
* <dd>zzzz is the time zone offset in hours and minutes (four decimal digits
* <dd>"hhmm") relative to GMT, preceded by a "+" or "-" character (
* <dd>-1200 through
* <dd>+1200). For instance, Pacific Standard Time zone is printed as
* <dd>-0800. GMT is printed as
* <dd>+0000.
* </ul>
*
* @return a string representation of this date.
*/
public static String toISO8601String(Calendar calendar) {
// Printing in the absence of a Calendar
// implementation class is not supported
if (calendar == null) {
return "0000 00 00 00 00 00 +0000";
}
int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH) + 1;
int day = calendar.get(Calendar.DAY_OF_MONTH);
int hour_of_day = calendar.get(Calendar.HOUR_OF_DAY);
int hour = calendar.get(Calendar.HOUR);
int minute = calendar.get(Calendar.MINUTE);
int seconds = calendar.get(Calendar.SECOND);
String yr = Integer.toString(year);
// The total size of the string buffer
// yr.length+1+2+1+2+1+2+1+2+1+2+1+5 = 25 + yr.length
StringBuffer sb = new StringBuffer(25 + yr.length());
appendFourDigits(sb, year).append(' ');
appendTwoDigits(sb, month).append(' ');
appendTwoDigits(sb, day).append(' ');
appendTwoDigits(sb, hour_of_day).append(' ');
appendTwoDigits(sb, minute).append(' ');
appendTwoDigits(sb, seconds).append(' ');
// TimeZone offset is represented in milliseconds.
// Convert the offset to minutes:
TimeZone t = calendar.getTimeZone();
int zoneOffsetInMinutes = t.getRawOffset() / 1000 / 60;
if (zoneOffsetInMinutes < 0) {
zoneOffsetInMinutes = Math.abs(zoneOffsetInMinutes);
sb.append('-');
} else {
sb.append('+');
}
int zoneHours = zoneOffsetInMinutes / 60;
int zoneMinutes = zoneOffsetInMinutes % 60;
appendTwoDigits(sb, zoneHours);
appendTwoDigits(sb, zoneMinutes);
return sb.toString();
}
