java关于日期的一些常用方法总结

001public 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}