我的日期工具类

public class DateUtils {


private static Logger logger = Logger.getLogger(DateUtils.class);


public static Date dayBegin(Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(Calendar.HOUR_OF_DAY, 0);
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
return calendar.getTime();
}


public static Date nextDay(Date date) {
Calendar c = Calendar.getInstance();
c.setTime(date);
c.add(Calendar.DAY_OF_MONTH, 1);
return c.getTime();
}


public static Date previousDay(Date date) {
Calendar c = Calendar.getInstance();
c.setTime(date);
c.add(Calendar.DAY_OF_MONTH, -1);
return c.getTime();
}


public static Date addDay(Date date, int day) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.DAY_OF_MONTH, day);
return calendar.getTime();
}

public static int getMargin(Date first,Date secord){
Calendar firstCalendar = Calendar.getInstance();
firstCalendar.setTime(first);
long time1 = firstCalendar.getTimeInMillis();
Calendar secordCalendar = Calendar.getInstance();
secordCalendar.setTime(secord);
long time2 = secordCalendar.getTimeInMillis();
long betweenDays = (time2-time1)/(1000*3600*24);
return Integer.parseInt(String.valueOf(betweenDays));
}


}