今天，昨天，三天前计算

DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");

Date date = df.parse(dates);

Calendar old = Calendar.getInstance();

old.setTime(date);

Calendar today = Calendar.getInstance();

today.set(Calendar.HOUR, 0);

today.set(Calendar.MINUTE, 0);

today.set(Calendar.SECOND, 0);

old.set(Calendar.HOUR, 0);

old.set(Calendar.MINUTE, 0);

old.set(Calendar.SECOND, 0);

// 老的时间减去今天的时间

long intervalMilli = old.getTimeInMillis() - today.getTimeInMillis();

int xcts = (int) (intervalMilli / (24 * 60 * 60 * 1000));

// -2:三天 -1：昨天 0：今天

if (xcts >= 20 && xcts <= 0) {

System.out.println(String.valueOf(xcts));

return xcts;

} else {

System.out.println("一月前");

return 1;

}