java关于日期的一些常用方法总结

001 public class DateUtil {
002
003     //泽勒一致性公式计算星期几
004     public static String getWeekOfDate(int year, int month, int day) {
005         int q = day;
006         int m;
007         String weekday[] = new String[] { "Saturday", "Sunday", "Monday",
008                 "Tuesday", "Wednessday", "Thursday", "Friday" };
009         switch (month) {
010         case 1:
011             m = 13;
012             year = year - 1;
013             break;
014         case 2:
015             m = 14;
016             year = year - 1;
017             break;
018         default:
019             m = month;
020             break;
021         }
022         int j = year / 100;
023         int k = year % 100;
024         int h = (q + 26 * (m + 1) / 10 + k + k / 4 + j / 4 + 5 * j) % 7;
025         return weekday[h];
026     }
027
028     //计算两个时间段之间的星期数
029     public static Object countTwoDayWeek(String startDate, String endDate) {
030         if (StringUtils.isNotEmpty(startDate)
031                 && StringUtils.isNotEmpty(endDate)) {
032             long between_days=getDaysBetweenDates(startDate, endDate);
033             Double days = Double.parseDouble(String.valueOf(between_days));
034             if ((days / 7) > 0 && (days / 7) <= 1) {
035                 // 不满一周的按一周算
036                 return 1;
037             } else if (days / 7 > 1) {
038                 int day = days.intValue();
039                 if (day % 7 > 0) {
040                     return day / 7 + 1;
041                 } else {
042                     return day / 7;
043                 }
044             } else if ((days / 7) == 0) {
045                 return 0;
046             } else {
047                 // 负数返还null
048                 return null;
049             }
050         }
051         return null;
052     }
053
054     //计算两个时间段的天数
055     public static long getDaysBetweenDates(String startDate, String endDate) {
056         if (StringUtils.isNotEmpty(startDate)
057                 && StringUtils.isNotEmpty(endDate)) {
058             DateFormat ft = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
059             Date start = null;
060             Date end = null;
061             try {
062                 start = ft.parse(startDate);
063                 end = ft.parse(endDate);
064             } catch (ParseException e) {
065                 // TODO Auto-generated catch block
066                 e.printStackTrace();
067             }
068             Calendar cal = Calendar.getInstance();
069             cal.setTime(start);
070             long time1 = cal.getTimeInMillis();
071             cal.setTime(end);
072             long time2 = cal.getTimeInMillis();
073             long between_days = (time2 - time1) / (1000 * 3600 * 24);
074             return between_days;
075         }
076         return 0;
077     }
078
079     //计算两个时间段之间的月数
080     public static int getMonthSpace(String startDate, String endDate) {
081         DateFormat ft = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
082         Calendar c1 = Calendar.getInstance();
083         Calendar c2 = Calendar.getInstance();
084         try {
085             c1.setTime(ft.parse(startDate));
086             c2.setTime(ft.parse(endDate));
087         } catch (ParseException e) {
088             e.printStackTrace();
089         }
090         if (c1.getTimeInMillis() < c2.getTimeInMillis())
091             return 0;
092         int year1 = c1.get(Calendar.YEAR);
093         int year2 = c2.get(Calendar.YEAR);
094         int month1 = c1.get(Calendar.MONTH);
095         int month2 = c2.get(Calendar.MONTH);
096         int day1 = c1.get(Calendar.DAY_OF_MONTH);
097         int day2 = c2.get(Calendar.DAY_OF_MONTH);
098         // 获取年的差值 假设 d1 = 2015-8-16 d2 = 2011-9-30
099         int yearInterval = year1 - year2;
100         // 如果 d1的 月-日 小于 d2的 月-日 那么 yearInterval-- 这样就得到了相差的年数
101         if (month1 < month2 || month1 == month2 && day1 < day2)
102             yearInterval--;
103         // 获取月数差值
104         int monthInterval = (month1 + 12) - month2;
105         if (day1 < day2)
106             monthInterval--;
107         monthInterval %= 12;
108         return yearInterval * 12 + monthInterval;
109     }
110
111     public static void main(String[] args) {
112         System.out.println(DateUtil.getWeekOfDate(2017, 9, 30));
113         System.out.println(DateUtil.getDaysBetweenDates("2016-09-30 06:30:15",
114                 "2018-09-30 20:30:30"));
115         System.out.println(DateUtil.getMonthSpace("2016-09-30 06:30:15",
116                 "2015-08-31 05:30:30"));
117         System.out.println(DateUtil.countTwoDayWeek("2017-09-30 06:30:15",
118                 "2017-10-15 05:30:30"));
119     }
120 }