java获取时间戳几天前

N天前开始时间

   /* N天开始时间
    * 1 == 昨天
    * 2 == 前天
    * 3 == 以此类推
    */
    public static long NumberOfDaysStartUnixTime(int NumberOfDays ) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(calendar.get(Calendar.YEAR),calendar.get(Calendar.MONTH),calendar.get(Calendar.DAY_OF_MONTH)-NumberOfDays,0,0,0);
        long yesterdayStart  = calendar.getTimeInMillis();
		return yesterdayStart;
     }

N天前结束时间

/* N天前结束时间
     * 1 == 昨天
     * 2 == 前天
     * 3 == 以此类推
     */
    public static long NumberOfDaysEndUnixTime(int NumberOfDays) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(calendar.get(Calendar.YEAR),calendar.get(Calendar.MONTH),calendar.get(Calendar.DAY_OF_MONTH)-NumberOfDays,23,59,59);
        long yesterdayEnd = calendar.getTimeInMillis();
        return yesterdayEnd;
    }