一年的周数

java获取一年的周数和间隔天数

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

public class Test {

    private static Date deformatDatetime(String strDate, String fmt) {
        try {
            if (fmt == null) {
                return (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",
                        java.util.Locale.ENGLISH)).parse(strDate);
            } else {
                return (new SimpleDateFormat(fmt, java.util.Locale.ENGLISH))
                        .parse(strDate);
            }
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }
    private static String datetimeToString(Date dt, String fmt) {
        if (fmt == null) {
            return (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",
                    java.util.Locale.ENGLISH)).format(dt);
        } else {
            return (new SimpleDateFormat(fmt, java.util.Locale.ENGLISH))
                    .format(dt);
        }
    }
    private static class DateRange{
        public Date startDate;
        public Date endDate;
        public DateRange(){

        }
        public DateRange(Date dt1,Date dt2){
            startDate=dt1;
            endDate=dt2;
        }
    }
    /**
     * 根據年份獲得該年所有周次及每周的開始-結束日期
     * @param pvnYear
     * @return
     */
    private static LinkedHashMap<Integer,DateRange> getWeeksDetByYear(int pvnYear){
        LinkedHashMap<Integer, DateRange> lvRet=new LinkedHashMap<Integer,DateRange>();
        Calendar lvCal=Calendar.getInstance();
        lvCal.setFirstDayOfWeek(Calendar.MONDAY);

        Date lvDt=deformatDatetime(String.valueOf(pvnYear)+"-01-01 00:00:00", null);
        lvCal.setTime(lvDt);
        int lvWeek=1;
        while (true) {
            lvCal.set(Calendar.DAY_OF_WEEK, lvCal.getFirstDayOfWeek()); // Monday
            Date lvFirstDt=lvCal.getTime();
            if (lvFirstDt.getYear()+1900<pvnYear){
                lvFirstDt=lvDt;
            }
            if (lvFirstDt.getYear()+1900>pvnYear) break;
            lvCal.set(Calendar.DAY_OF_WEEK, lvCal.getFirstDayOfWeek()+6); // Sunday?
            Date lvLastDt=lvCal.getTime();
            if (lvLastDt.getYear()+1900>pvnYear){
                lvLastDt=deformatDatetime(String.valueOf(pvnYear+1)+"-01-01 00:00:00", null);
                lvCal.setTime(lvLastDt);
                lvCal.add(Calendar.DAY_OF_YEAR, -1);
                lvLastDt=lvCal.getTime();
            }
            lvRet.put(Integer.valueOf(lvWeek), new DateRange(lvFirstDt, lvLastDt));
            lvWeek++;
            lvCal.add(Calendar.WEEK_OF_YEAR, 1);
        }
        return lvRet;
    }
    public static void main(String[] args) throws  Exception{
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        LinkedHashMap<Integer,DateRange>  lvRet=getWeeksDetByYear(2011);
        for (Map.Entry<Integer, DateRange> item:lvRet.entrySet()){
            String startDate = datetimeToString(item.getValue().startDate,"yyyy-MM-dd");
            String endDate = datetimeToString(item.getValue().endDate,"yyyy-MM-dd");
            Date date1 = format.parse(startDate);
            Date date2 = format.parse(endDate);
            int diff = differentDays(date1,date2);
            System.out.println(String.format("Week: %d, %s - %s", item.getKey(),datetimeToString(item.getValue().startDate,"yyyy-MM-dd"),
                    datetimeToString(item.getValue().endDate,"yyyy-MM-dd"))+" ----------"+diff);
        }
    }

    public static int differentDays(Date date1,Date date2)
    {
        Calendar cal1 = Calendar.getInstance();
        cal1.setTime(date1);

        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(date2);
        int day1= cal1.get(Calendar.DAY_OF_YEAR);
        int day2 = cal2.get(Calendar.DAY_OF_YEAR);

        int year1 = cal1.get(Calendar.YEAR);
        int year2 = cal2.get(Calendar.YEAR);
        if(year1 != year2)   //同一年
        {
            int timeDistance = 0 ;
            for(int i = year1 ; i < year2 ; i ++)
            {
                if(i%4==0 && i%100!=0 || i%400==0)    //闰年
                {
                    timeDistance += 366;
                }
                else    //不是闰年
                {
                    timeDistance += 365;
                }
            }

            return timeDistance + (day2-day1) ;
        }
        else    //不同年
        {
            return day2-day1;
        }
    }
}