java获取当前日期，前一天，前N天，去年同期等日期

private EZPageRequest getStartAndEndDate() {
    EZPageRequest pageRequest = new EZPageRequest();
    
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
  
    Calendar calendar = Calendar.getInstance();
    Date time2 = calendar.getTime();
    //当前时间
    String currentTime = format.format(time2);
    log.info("当前时间--{}",currentTime);
    pageRequest.setCurrentDate(currentTime);
    //获取今年的第一天   清除时间为初始时间值  
    calendar.clear();
    //将初始年份设置为当前年份
    Calendar currCal=Calendar.getInstance();
    calendar.set(Calendar.YEAR,currCal.get(Calendar.YEAR));
    Date time = calendar.getTime();
    String firstDay =  format.format(time);
    log.info("今年的第一天--{}",firstDay);
    pageRequest.setThisDate(firstDay);

    //获取去年同期时间 年份减一
    Calendar endCal= Calendar.getInstance();
    endCal.set(Calendar.YEAR,currCal.get(Calendar.YEAR));
    endCal.roll(Calendar.YEAR, -1);
    Date time1 = endCal.getTime();
    String format1 = format.format(time1);
    pageRequest.setEndTime(format1);
    log.info("去年同期时间--{}",format1);

     //获取去年第一天时间
    Calendar instance = Calendar.getInstance();
    instance.clear();
    instance.set(Calendar.YEAR,currCal.get(Calendar.YEAR));
    instance.roll(Calendar.YEAR, -1);
    String endDate = format.format(instance.getTime());
    pageRequest.setStartTime(endDate);
    log.info("去年的第一天--{}",endDate);
    return pageRequest;
}