Convert a date to a unix timestamp using daylight savings.
long GetUnixdate(java.util.Date dt) {
long unixtimestamp;
int hour;
int min;
int sec;
long days; // days difference
long secinday;
long MsInDay;
Calendar calendar = Calendar.getInstance();
calendar.setTime(dt);
hour = calendar.get(Calendar.HOUR_OF_DAY);
min = calendar.get(Calendar.MINUTE);
sec = calendar.get(Calendar.SECOND);
secinday = 86400;
MsInDay = secinday * 1000;
days = calendar.getTimeInMillis() / MsInDay;
unixtimestamp = (days * secinday) + (hour * 3600) + (min * 60) + sec;
return unixtimestamp;
}