Workaround for CronSequenceGenerator Last day of m

问题:

Ok so here it is I want to schedule a task to run on last day of every month on 10:10 AM.My cron expression is

0 10 10 L * ?

Now the problem is CronSequenceGenerator is throwing NumberFormatException for 'L' value.This means Spring's CronSequenceGenerator does'nt support this kind of expression.How to do this in any other way (workaround).I don't want to use quartz or Does spring's gonna support this in new releases.

Here is full stacktrace:

Exception in thread "main" java.lang.NumberFormatException: For input string: "L"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:492)
    at java.lang.Integer.valueOf(Integer.java:582)
    at org.springframework.scheduling.support.CronSequenceGenerator.getRange(CronSequenceGenerator.java:324)
    at org.springframework.scheduling.support.CronSequenceGenerator.setNumberHits(CronSequenceGenerator.java:297)
    at org.springframework.scheduling.support.CronSequenceGenerator.setDays(CronSequenceGenerator.java:275)
    at org.springframework.scheduling.support.CronSequenceGenerator.setDaysOfMonth(CronSequenceGenerator.java:266)
    at org.springframework.scheduling.support.CronSequenceGenerator.parse(CronSequenceGenerator.java:239)
    at org.springframework.scheduling.support.CronSequenceGenerator.<init>(CronSequenceGenerator.java:81)
    at org.springframework.scheduling.support.CronTrigger.<init>(CronTrigger.java:54)
    at org.springframework.scheduling.support.CronTrigger.<init>(CronTrigger.java:44)
    at com.hcdc.coedp.datantar.scheduler.SchedulerUtil.start(SchedulerUtil.java:75)
    at com.hcdc.coedp.datantar.scheduler.SchedulerUtil.changeTrigger(SchedulerUtil.java:106)
    at com.hcdc.coedp.datantar.scheduler.SchedulingService.scheduleTransfer(SchedulingService.java:70)
    at com.hcdc.coedp.datantar.scheduler.Scheduler.schedule(Scheduler.java:107)
    at main.Main.main(Main.java:47)

Update:

Following is my scheduling method

 /**
    * Schedule a task {@link Task} with a specified cron expression.
    * @param task {@link Task}
    * @param cronExpression cron expression to be applied must be a vaild one.
    * @param taskName
    * @return 
    */
     public String start(Task task, String cronExpression, String taskName) {
        CronTrigger trigger = new CronTrigger(cronExpression);//line 2

        CronSequenceGenerator generator = new CronSequenceGenerator(cronExpression, TimeZone.getTimeZone("GMT+5:30"));
        List<Date> dateList = new ArrayList<>(5);
        Date currentDate = new Date();
        for (int i = 0; i < 5; i++) {
            currentDate = generator.next(currentDate);
            dateList.add((currentDate));
            System.out.println("Next Exceution times are" + currentDate);
        }
        ScheduledFuture sf = tps.schedule(task, trigger);

        //TODO Save this scheduled future with a specific task name.
        ContextHolder.schduledFutureMap.put(taskName, sf);
        return cronExpression;
    }

And on line 2 it throws NumberFormatException when I pass specified cron expression.

回答1:

This feature is not in standard cron expression syntax. So probably Spring will never implement it. Looking at the code, I can't see any surgical solution extending CronSequenceGenerator. So why you just don't use Quartz since it's a particular feature?

Depending on your exact need, you could implement your own Trigger. Something like:

import java.util.Date;

import org.joda.time.LocalDate;
import org.joda.time.LocalTime;
import org.springframework.scheduling.Trigger;
import org.springframework.scheduling.TriggerContext;

public class LastDayOfMonthTrigger implements Trigger {

    private final LocalTime time;

    public LastDayOfMonthTrigger(LocalTime time) {
        this.time = time;
    }

    @Override
    public Date nextExecutionTime(TriggerContext ctx) {
        Date last = ctx.lastScheduledExecutionTime();
        LocalDate date = last == null ? new LocalDate() : new LocalDate(last).plusDays(1);
        LocalDate lastDay = date.dayOfMonth().withMaximumValue();
        return lastDay.toDateTime(time).toDate();
    }
}

回答2:

As a workaround I would schedule the execution for all dates

0 10 10 * * ?

and checked the actual date in the scheduled method

public void scheduledTask() {
    Calendar c = Calendar.getInstance();
    if (c.get(Calendar.DATE) == c.getActualMaximum(Calendar.DATE)) {
        ...
    }
}

回答3:

Optimized version which runs only on the last day of a month:

@Scheduled(cron = "0 55 23 28-31 * ?")
public void doStuffOnLastDayOfMonth() {
    final Calendar c = Calendar.getInstance();
    if (c.get(Calendar.DATE) == c.getActualMaximum(Calendar.DATE)) {
        // do your stuff
    }
}