common_helper/src/main/java/com/xiongyingqi/util/DateHelper.java
public static int diffOfDay(Date date1, Date date2) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(date1.getTime());
        int i = calendar.get(Calendar.DAY_OF_YEAR);
        Calendar calendar2 = Calendar.getInstance();
        calendar2.setTimeInMillis(date2.getTime());
        int i2 = calendar2.get(Calendar.DAY_OF_YEAR);
        return i2 - i;
    }
public static int diffOfDay(Date date1, Date date2) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(date1.getTime());
        int i = calendar.get(Calendar.DAY_OF_YEAR);
        Calendar calendar2 = Calendar.getInstance();
        calendar2.setTimeInMillis(date2.getTime());
        int i2 = calendar2.get(Calendar.DAY_OF_YEAR);
        return i2 - i;
    }
计算日期之间相差多少天

@param date1 较前日期
@param date2 较后日期
@return