Java对日期Date类进行日期加减运算，年份加减，月份加减

 package com.cy;

 import java.security.InvalidParameterException;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;

 public class DateUtils {
     private static final long MILLIS_IN_A_SECOND = 1000;

     private static final long SECONDS_IN_A_MINUTE = 60;

     private static final int MONTHS_IN_A_YEAR = 12;

     /**
      * 获得指定日期之后一段时期的日期。例如某日期之后3天的日期等 时间为23:59:59。
      *
      * @param origDate
      *            基准日期
      * @param amount
      *            时间数量
      * @param timeUnit
      *            时间单位，如年、月、日等。用Calendar中的常量代表
      * @return {@link Date}
      */
     public static final Date dateAfter(Date origDate, int amount, int timeUnit) {
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(origDate);
         // 将小时至0
         // calendar.set(Calendar.HOUR_OF_DAY, 23);
         // 将分钟至0
         // calendar.set(Calendar.MINUTE, 59);
         // 将秒至0
         // calendar.set(Calendar.SECOND, 59);
         // 将毫秒至0
         // calendar.set(Calendar.MILLISECOND, 0);
         calendar.add(timeUnit, amount);
         return calendar.getTime();
     }

     /**
      * 获得指定日期之后一段时期的日期。例如某日期之后3天的日期等。
      *
      * @param origDate
      *            基准日期
      * @param amount
      *            时间数量
      * @param timeUnit
      *            时间单位，如年、月、日等。用Calendar中的常量代表
      * @return {@link Date}
      */
     public static final Date timeAfter(Date origDate, int amount, int timeUnit) {
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(origDate);
         calendar.add(timeUnit, amount);
         return calendar.getTime();
     }

     /**
      * 获得指定日期之前一段时期的日期。例如某日期之前3天的日期等。
      *
      * @param origDate
      *            基准日期
      * @param amount
      *            时间数量
      * @param timeUnit
      *            时间单位，如年、月、日等。用Calendar中的常量代表
      * @return {@link Date}
      */
     public static final Date dateBefore(Date origDate, int amount, int timeUnit) {
         Calendar calendar = Calendar.getInstance();
         calendar.add(timeUnit, -amount);
         return calendar.getTime();
     }

     /**
      * 根据年月日构建日期对象。注意月份是从1开始计数的，即month为1代表1月份。
      *
      * @param year
      *            年
      * @param month
      *            月。注意1代表1月份，依此类推。
      * @param day
      *            日
      * @return {@link Date}
      */
     public static Date date(int year, int month, int date) {
         Calendar calendar = Calendar.getInstance();
         calendar.set(year, month - 1, date, 0, 0, 0);
         calendar.set(Calendar.MILLISECOND, 0);
         return calendar.getTime();
     }

     /**
      * 计算两个日期（不包括时间）之间相差的周年数
      *
      * @param date1
      *            开始时间
      * @param date2
      *            结束时间
      * @return {@link Integer}
      */
     public static int getYearDiff(Date date1, Date date2) {
         if (date1 == null || date2 == null) {
             throw new InvalidParameterException("date1 and date2 cannot be null!");
         }
         if (date1.after(date2)) {
             throw new InvalidParameterException("date1 cannot be after date2!");
         }

         Calendar calendar = Calendar.getInstance();
         calendar.setTime(date1);
         int year1 = calendar.get(Calendar.YEAR);
         int month1 = calendar.get(Calendar.MONTH);
         int day1 = calendar.get(Calendar.DATE);

         calendar.setTime(date2);
         int year2 = calendar.get(Calendar.YEAR);
         int month2 = calendar.get(Calendar.MONTH);
         int day2 = calendar.get(Calendar.DATE);

         int result = year2 - year1;
         if (month2 < month1) {
             result--;
         } else if (month2 == month1 && day2 < day1) {
             result--;
         }
         return result;
     }

     /**
      * 计算两个日期（不包括时间）之间相差的整月数
      *
      * @param date1
      *            开始时间
      * @param date2
      *            结束时间
      * @return {@link Integer}
      */
     public static int getMonthDiff(Date date1, Date date2) {
         if (date1 == null || date2 == null) {
             throw new InvalidParameterException("date1 and date2 cannot be null!");
         }
         if (date1.after(date2)) {
             throw new InvalidParameterException("date1 cannot be after date2!");
         }

         Calendar calendar = Calendar.getInstance();
         calendar.setTime(date1);
         int year1 = calendar.get(Calendar.YEAR);
         int month1 = calendar.get(Calendar.MONTH);
         int day1 = calendar.get(Calendar.DATE);

         calendar.setTime(date2);
         int year2 = calendar.get(Calendar.YEAR);
         int month2 = calendar.get(Calendar.MONTH);
         int day2 = calendar.get(Calendar.DATE);

         int months = 0;
         if (day2 >= day1) {
             months = month2 - month1;
         } else {
             months = month2 - month1 - 1;
         }
         return (year2 - year1) * MONTHS_IN_A_YEAR + months;
     }

     /**
      * 统计两个日期之间包含的天数。包含date1，但不包含date2
      *
      * @param date1
      *            开始时间
      * @param date2
      *            结束时间
      * @return {@link Integer}
      * @throws ParseException
      */
     public static int getDayDiff(Date date1, Date date2) {
         if (date1 == null || date2 == null) {
             throw new InvalidParameterException("date1 and date2 cannot be null!");
         }
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
         Date smdate;
         try {
             smdate = sdf.parse(sdf.format(date1));
             Date bdate = sdf.parse(sdf.format(date2));
             Calendar cal = Calendar.getInstance();
             cal.setTime(smdate);
             long time1 = cal.getTimeInMillis();
             cal.setTime(bdate);
             long time2 = cal.getTimeInMillis();
             long between_days = (time2 - time1) / (1000 * 3600 * 24);
             return Integer.parseInt(String.valueOf(between_days));
         } catch (ParseException e) {
             e.printStackTrace();
         }
         return 0;
     }

     /**
      * 计算time2比time1晚多少分钟，忽略日期部分
      *
      * @param time1
      * @param time2
      * @return
      */
     public static int getMinuteDiffByTime(Date time1, Date time2) {
         long startMil = 0;
         long endMil = 0;
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(time1);
         calendar.set(1900, 1, 1);
         startMil = calendar.getTimeInMillis();
         calendar.setTime(time2);
         calendar.set(1900, 1, 1);
         endMil = calendar.getTimeInMillis();
         return (int) ((endMil - startMil) / MILLIS_IN_A_SECOND / SECONDS_IN_A_MINUTE);
     }

     /**
      * 计算时间是否是同一天
      *
      * @param dateA
      * @param dateB
      * @return
      */
     public static boolean areSameDay(Date dateA, Date dateB) {
         Calendar calDateA = Calendar.getInstance();
         calDateA.setTime(dateA);

         Calendar calDateB = Calendar.getInstance();
         calDateB.setTime(dateB);

         return calDateA.get(Calendar.YEAR) == calDateB.get(Calendar.YEAR)
                 && calDateA.get(Calendar.MONTH) == calDateB.get(Calendar.MONTH)
                 && calDateA.get(Calendar.DAY_OF_MONTH) == calDateB.get(Calendar.DAY_OF_MONTH);
     }

     /**
      * @Title: getCurrYearLast
      * @Description: 获取某年最后一天
      * @param date
      * @return Date
      */
     public static Date getCurrYearLast(Date date) {
         Calendar currCal = Calendar.getInstance();
         currCal.setTime(date);
         int currentYear = currCal.get(Calendar.YEAR);
         return getYearLast(currentYear);
     }

     private static Date getYearLast(int year) {
         Calendar calendar = Calendar.getInstance();
         calendar.clear();
         calendar.set(Calendar.YEAR, year);

         calendar.roll(Calendar.DAY_OF_YEAR, -1);
         // 将小时至0
         calendar.set(Calendar.HOUR_OF_DAY, 23);
         // 将分钟至0
         calendar.set(Calendar.MINUTE, 59);
         // 将秒至0
         calendar.set(Calendar.SECOND, 59);
         // 将毫秒至0
         calendar.set(Calendar.MILLISECOND, 0);

         Date currYearLast = calendar.getTime();
         return currYearLast;
     }
     /*
      * private static Date getYearLast(int year) { Calendar calendar =
      * Calendar.getInstance(); calendar.clear(); calendar.set(Calendar.YEAR,
      * year); calendar.roll(Calendar.DAY_OF_YEAR, -1); Date currYearLast =
      * calendar.getTime(); return currYearLast; }
      */
     /**
      *
      * @param args
      * @throws ParseException
      *
      * 根据结算周期数  对开始时间与结束时间进行分段
      */
     public static void main(String[] args) throws ParseException {
         /*开始时间*/
         Date startDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2017-1-20 10:31:36");
         /*结束时间*/
         Date endDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2017-5-12 10:31:36");
         /*周期数*/
         int solt = 2;
         ArrayList<Map<String, Object>> list = new ArrayList<>();

         while (startDate.getTime()<endDate.getTime()) {
             Map<String, Object> map = new HashMap<>();
             map.put("开始时间",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(startDate));
             startDate=dateAfter(startDate, solt, Calendar.MONTH);
             if (startDate.getTime()>endDate.getTime()) {
                 map.put("结束时间",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(endDate));

             } else {
                 map.put("结束时间",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(startDate));
             }
             list.add(map);
         }
         System.out.println(list);
     }
 }