1.將String日期轉化成Date：
DateUtils.parseDate(example, "yyyy-MM-dd")
2.將日期轉換成各種format樣式類型，舉個例子：
DateFormatUtils.format(example, "MM-dd");
DateFormatUtils.format(example,"yyyy.MM.dd");
3.月份減1
DateUtils.addMonths(example, -1);
4.天數加1
DateUtils.addDays(example, 1);
DateUtils 常用方法
boolean isSameDay(final Date date1, final Date date2)
boolean isSameDay(final Calendar cal1, final Calendar cal2)
boolean isSameInstant(final Date date1, final Date date2)
boolean isSameInstant(final Calendar cal1, final Calendar cal2)
boolean isSameLocalTime(final Calendar cal1, final Calendar cal2)
Date addYears(final Date date, final int amount)
Date addWeeks(final Date date, final int amount)
Date addHours(final Date date, final int amount)
Date addMinutes(final Date date, final int amount)
Date addSeconds(final Date date, final int amount)
Date addMilliseconds(final Date date, final int amount)
Date setYears(final Date date, final int amount)
Date setMonths(final Date date, final int amount)
Date setDays(final Date date, final int amount)
Date setHours(final Date date, final int amount)
Date setMinutes(final Date date, final int amount)
Date round(final Date date, final int field)
round 類似於“四捨五入”
truncate 按位截取
ceiling 取上限？
計算從當前fragment到date已經過去了多少個（年、月、周、日、時、分、秒、毫秒）
long getFragmentInMinutes(final Date date, final int fragment)
long getFragmentInHours(final Date date, final int fragment)
long getFragmentInDays(final Date date, final int fragment)
long getFragmentInMilliseconds(final Calendar calendar, final int fragment)
long getFragmentInSeconds(final Calendar calendar, final int fragment)
