Calendar 对象的使用实例

1.Calendar demo例子

Java Calendar 类时间操作，示范代码。

public class CalendarDemo {
    private static SimpleDateFormat date_format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    public static void main(String[] args) {   

        //获取calendar实例;
        Calendar calendar = Calendar.getInstance();   

        //判断calendar是不是GregorianCalendar类的实例;
        if(calendar instanceof GregorianCalendar){
            System.out.println("属于GregorianCalendar类的实例!");
        }   

        //从calendar对象中获得date对象，当前时间;
        Date dates =  calendar.getTime();   

        //格式化时间;
        String date_str= date_format.format(dates);
        System.out.println(date_str);   

        //设置月份05；代表日历的月份6月，因为月份从0开始。
        calendar.set(Calendar.MONTH, 05);   

        int months = calendar.get(Calendar.MONTH);
        System.out.println(months);  //输出05;   

        //设置日期为2011-07-24 09：59:50
        calendar.set(2011, 06, 24, 9, 59, 50);
        String getDate = date_format.format(calendar.getTime());
        System.out.println(getDate);   //输出2011-07-24 09:59:50;   

        //比较日前大小;
        if(new Date().getTime() > calendar.getTimeInMillis()){
            System.out.println("当前日期在后!");
        }else{
            System.out.println("当前日期在前!");
        }   

        //设置当前时间为:2011-07-24 11:06:00
        calendar.setTime(new Date());
        int year   = calendar.get(Calendar.YEAR);   //获取年;
        int month  = calendar.get(Calendar.MONTH);  //获取月;
        int date   = calendar.get(Calendar.DATE);   //获取天;
        int hour   = calendar.get(Calendar.HOUR);   //获取小时;
        int minute = calendar.get(Calendar.MINUTE); //获取分钟;
        int second = calendar.get(Calendar.SECOND); //获取秒钟;
        int hour_of_day = calendar.get(Calendar.HOUR_OF_DAY);    //第几个小时，
        int day_of_month  = calendar.get(Calendar.DAY_OF_MONTH); //这天，在一个月内是第几天.
        int day_of_week = calendar.get(Calendar.DAY_OF_WEEK);    //这天，在一周内，是第几天.
        int day_of_year = calendar.get(Calendar.DAY_OF_YEAR);    //这天，在一年内，是第几天。
        int week_of_year = calendar.get(Calendar.WEEK_OF_YEAR);  //这周，在一年内是第几周;
        int week_of_month = calendar.get(Calendar.WEEK_OF_MONTH);//这周，在这个月是第几周;以以星为标准；
        int zone_offset = calendar.get(Calendar.ZONE_OFFSET);    //获取时区;
        int day_of_week_in_month = calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH);  //某月中第几周，按这个月1号算，1号起就是第1周，8号起就是第2周。以月份天数为标准
        int r = calendar.get(Calendar.AM_PM);
        if(r==calendar.AM){
            System.out.println("现在是上午");
        }   

        if(r==calendar.PM){
            System.out.println("现在是下午");
        }
        System.out.println("==================================================");
        System.out.println(year);
        System.out.println(month);
        System.out.println(date);
        System.out.println(hour);
        System.out.println(minute);
        System.out.println(second);
        System.out.println(hour_of_day);
        System.out.println(day_of_month);
        System.out.println(day_of_week);
        System.out.println(day_of_year);
        System.out.println(week_of_year);
        System.out.println(week_of_month);
        System.out.println(zone_offset);
        System.out.println(day_of_week_in_month);
    }
}

2.项目中应用

@RequestMapping(method = RequestMethod.GET, produces = { "application/json" })
    @ResponseBody
    public ListWithTotalCount<AuctionsDTO> aucLotQuery(@ModelAttribute("selectedAgency") SysAgencyDto selectedAgency,
        int page, int rows, String order, String sort) {
        Pageable pageable;
        String agencyId = selectedAgency.getId().toString();

        if (sort != null && !sort.isEmpty()) {
            pageable = new PageRequest(page - 1, rows, Direction.fromStringOrNull(order), sort);
        } else {
            pageable = new PageRequest(page - 1, rows);
        }

        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MILLISECOND, 0);
        Date less = cal.getTime();
        cal.set(Calendar.HOUR_OF_DAY, 23);
        cal.set(Calendar.MINUTE, 59);
        cal.set(Calendar.SECOND, 59);
        cal.set(Calendar.MILLISECOND, 999);
        Date great = cal.getTime();
        Specification<Auction> spec = (root, query, cb) -> {
            List<Predicate> predicates = new ArrayList<Predicate>();

            if (agencyId != null && !agencyId.isEmpty() && !"0".equals(agencyId)) {
                Predicate predicate = cb.equal(root.get(Auction_.agencyId), agencyId);
                predicates.add(predicate);
            }

            Predicate published = cb.equal(root.get(Auction_.isPublished), Auction.AUCLOT_ISPUBLISHED_FINISH);
            predicates.add(published);

　　　　　　  //获取当天的检索条件
            Predicate time =cb.between(root.get(Auction_.startTime),less,great);
            predicates.add(time);

            return cb.and(predicates.toArray(new Predicate[0]));
        };

        Page<Auction> pageresult = auctionRepository.findAll(spec, pageable);
        List<AuctionsDTO> dtoList = (new AuctionsDTOAssembler()).toDTOList(pageresult.getContent());

        return new ListWithTotalCount<AuctionsDTO>(dtoList, (int) pageresult.getTotalElements());
    }