根据给定年份和周数获取指定周的开始结束日期

　　/**
     * 获取给定年份的日历
     *
     * @param year 年
     * @return
     */
    private Calendar getCalendarFormYear(int year) {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        cal.set(Calendar.YEAR, year);
        return cal;
    }

　　/**
     *  根据给定日期获取当前日期所属周数
     *
     * @param givenDate 日期
     * @return
     */
    public static Integer getWeekNo(String givenDate){
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        try {
            date = format.parse(givenDate);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        Calendar calendar = Calendar.getInstance();
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        calendar.setTime(date);
        return calendar.get(Calendar.WEEK_OF_YEAR);
    }

/** * 获取给定周的开始日期

     *
     * @param year 年
     * @param weekNo 周
     * @return
     */
    public String getStartDayByWeekNo(int year, int weekNo) {
        Calendar cal = getCalendarFormYear(year);
        cal.set(Calendar.WEEK_OF_YEAR, weekNo);
        return cal.get(Calendar.YEAR) + "-" + (cal.get(Calendar.MONTH) + 1) + "-" +
                cal.get(Calendar.DAY_OF_MONTH);

    }

    /**
     * 获取给定周的结束日期
     *
     * @param year 年
     * @param weekNo 周
     * @return
     */
    public String getEndDayByWeekNo(int year, int weekNo) {
        Calendar cal = getCalendarFormYear(year);
        cal.set(Calendar.WEEK_OF_YEAR, weekNo);
        cal.add(Calendar.DAY_OF_WEEK, 6);
        return cal.get(Calendar.YEAR) + "-" + (cal.get(Calendar.MONTH) + 1) + "-" +
                cal.get(Calendar.DAY_OF_MONTH);
    }