获取当前时间的年月日

注意使用Date获取当前年月日会出现一些问题，一般选择Calendar获取

Calendar calendar = Calendar.getInstance();

int year = calendar.get(Calendar.YEAR);

int month = calendar.get(Calendar.MONTH) + 1;

int day = calendar.get(Calendar.DAY_OF_MONTH);

int hour = calendar.get(Calendar.HOUR_OF_DAY);

int minute = calendar.get(Calendar.MINUTE);

int millisecond = calendar.get(Calendar.SECOND);