java的 System.currentTimeMillis() 与当前计算机时间

public static void main(String[] args) {
    int   currentDay=TimeDateUtil.getCurrentDay();
　　long currentTime = currentDay*TimeDateUtil.ONEDAY;
　　long tomorrowZeroTime =currentTime + TimeDateUtil.ONEDAY*2;
　　int todayZeroTimeReturnInt = TimeDateUtil.getTodayZeroTimeReturnInt();
　　//todayZeroTimeReturnInt:1605024000,currentDay:18576,currentTime:1604966400000
　　System.out.println("todayZeroTimeReturnInt:"+todayZeroTimeReturnInt+",currentDay:"+currentDay+",currentTime:"+currentTime+",currentSystemTime:"+System.currentTimeMillis());
　　System.out.println("nowZeroTime:"+String.format("%tc", todayZeroTimeReturnInt*1000L));//当前时间的凌晨时间
　　System.out.println("systemCurrentTime:"+String.format("%tc", System.currentTimeMillis()));
　　System.out.println("currentTime:"+String.format("%tc", currentTime));
　　System.out.println("tomorrowZeroTime:"+String.format("%tc", tomorrowZeroTime));
}

/**
 * 时间日期工具类
 * @author 哈皮
 *
 */
public class TimeDateUtil {

    /**
     * 一天的时间
     */
    public static final long ONEDAY = 3600*24*1000;

    /**当前总天*/
    public static int getCurrentDay(){
        return getTodayZeroTimeReturnInt()/ONE_DAY;
    }

    /**
     * 获取今天零时的时间
     * @return 零时以int类型返回的数值
     */
    public static int getTodayZeroTimeReturnInt(){
        long todayZeroTime = getTodayZeroTime();
        return (int) (todayZeroTime/1000);
    }

    /**
     * 获取今天零时的时间
     * @return 零时以long类型返回的数值
     */
    public static long getTodayZeroTime(){
        long now = System.currentTimeMillis();
        long more = now%ONEHOUR;
        int nowHour = getHour();
        long zeroTime = now-(nowHour*ONEHOUR+more);
        return zeroTime;
    }
}