quartz踩过的坑-判断时间表达式是否可用

public class TaskUtils {

    /**
     * 校验定时任务格式
     * @param expressionStr
     * @return
     */
    public static boolean isValidExpressionStr(String expressionStr){
        if(StringUtil.isBlank(expressionStr)){
            return false;
        }
        return CronExpression.isValidExpression(expressionStr);
    }

    /**
     * 校验表达式是否能触发(相对于当前时间)
     * @param expressionStr
     * @return
     * @throws ParseException 
     */
    public static boolean isCanDoExpression(String expressionStr) throws ParseException{
        //先判断表达式格式是否正确
        if(!isValidExpressionStr(expressionStr)){
            return false;
        }
        CronTriggerImpl triggerImpl=new CronTriggerImpl();
        triggerImpl.setCronExpression(expressionStr);
        Date date=triggerImpl.computeFirstFireTime(null);
        return date!=null&&date.after(new Date());
    }

    /**
     * 获取一段时间内可以运行日期
     * @param expressionStr
     * @param beginDate
     * @param endDate
     * @return
     * @throws ParseException
     */
    public static List<Date> getCanDoBetween(String expressionStr,Date beginDate,Date endDate) throws ParseException{
        //先判断表达式格式是否正确
        if(!isValidExpressionStr(expressionStr)){
            return null;
        }
        if(endDate.before(beginDate)){
            return null;
        }
        CronTriggerImpl triggerImpl=new CronTriggerImpl();
        triggerImpl.setCronExpression(expressionStr);
        return TriggerUtils.computeFireTimesBetween(triggerImpl, null, beginDate, endDate);

    }

    public static void main(String[] args) throws ParseException {
        Calendar calendar=Calendar.getInstance();
        calendar.add(Calendar.YEAR, -1);
        List<Date> resultList=getCanDoBetween("0 0 0/4 8 8 ?", calendar.getTime(), new Date());
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        for (Date date : resultList) {
            System.out.println(sdf.format(date));
        }

    }
}