Package jakarta.enterprise.concurrent

Class CronTrigger

java.lang.Object
jakarta.enterprise.concurrent.CronTrigger
All Implemented Interfaces:
Trigger, ZonedTrigger
public class CronTrigger extends Object implements ZonedTrigger

Cron-based Trigger implementation, which supports 5 or 6 fields delimited by a single space character, plus a ZoneId. Basic cron syntax is supported. For more advanced scenarios, you can subclass this implementation or combine multiple CronTrigger instances in a Trigger implementation of your own.

Cron Expression Fields
seconds (optional)0-59, *. When absent, 0 is assumed
minutes0-59, *
hours0-23, *
dayOfMonth0-31, *, L
month1-12, JAN-DEC, January-December, *
dayOfWeekSUN-SAT, Sunday-Saturday, 0-7, *. 0 and 7 both represent Sunday: 0 to designate the first day of the week, and 7 for consistency with DayOfWeek.

Cron Expression Syntax
, delimits lists for all fields. For example, MON,WED,FRI or MAY,SEP
- delimits ranges for all fields. For example, MON-FRI or 9-17
/ specifies a repeating increment for all fields except dayOfWeek. For example, 6/7 for the hours field equates to 6,13,20.
# specifies an ordinal day of week. For example, FRI#1,SAT#L is the first Friday and last Saturday of the month.
# cannot be used within ranges (-) and increments (/).
* indicates any value is permitted.
L indicates the last day of the month. 2L indicates the second-to-last day, and so forth.

Cron Expression Examples
0 * * * * every hour at the top of the hour
0 9-17 * * MON-FRI weekdays from 9am to 5pm, at the top of each hour
0 13/3 * MAY-SEP SAT,SUN weekends from May to September, every 3 hours, starting at 1pm
30 10 * APR,AUG TUE#2,TUE#L second and last Tuesdays of April and August at 10:30am
15 22 4 10,20,L * * 4:22:15 AM on the 10th, 20th, and last day of every month
0 8-11,13-16 2L JAN-MAR * 8AM-11AM and 1PM-4PM on the second-to-last day of January, February, and March

A constructor is provided that accepts a cron expression such as the above and a timezone id. For example, 

 trigger = new CronTrigger("0 7 * SEP-MAY MON-FRI", ZoneId.of("America/New_York"));

Another constructor allows cron fields to be specified in a fluent manner, in any order. For example, 

 trigger = new CronTrigger(ZoneId.of("America/Los_Angeles"))
           .months(Month.DECEMBER)
           .daysOfMonth(24)
           .hours(16, 18);

The getNextRunTime method of this trigger determines the next run time based on the cron schedule. The skipRun method always returns false unless overridden by a subclass.

Methods of this class that configure the cron expression fields are not thread safe. It is the responsibility of the caller to ensure that initialization of the CronTrigger happens before it is supplied to a ManagedScheduledExecutorService and that the CronTrigger is not subsequently modified.

You can subclass CronTrigger to provide for more complex logic, such as in the following example of combining two triggers to schedule twice-a-month payroll on the 15th and last day of month or the prior Fridays when the former fall on a weekend: 

 public class PayrollTrigger extends CronTrigger {
     private final CronTrigger fridaysBeforeWeekendPayrollDay;

     PayrollTrigger() {
         // Every 15th and last day of the month that is a weekday,
         super("0 10 15,L * MON-FRI", ZoneId.of("America/Chicago"));

         // Every 13th, 14th, third-to-last, and second-to-last day of the month that is a Friday,
         fridaysBeforeWeekendPayrollDay = new CronTrigger(
                 "0 10 13,14,3L,2L * FRI", getZoneId());
     }

     public ZonedDateTime getNextRunTime(LastExecution lastExec, ZonedDateTime scheduledAt) {
         ZonedDateTime time1 = super.getNextRunTime(lastExec, scheduledAt);
         ZonedDateTime time2 = fridaysBeforeWeekendPayrollDay.getNextRunTime(lastExec, scheduledAt);
         return time1.isBefore(time2) ? time1 : time2;
     }
 }
Since:
3.0

  • Constructor Details

    • CronTrigger

      public CronTrigger(String cron, ZoneId zone)
      Constructor that accepts a cron expression.
      Parameters:
      cron - cron expression.
      zone - timezone ID to use for ZonedDateTime that is supplied to getNextRunTime and skipRun methods. Null indicates to use the system default.

    • CronTrigger

      public CronTrigger(ZoneId zone)
      Constructor for the fluent configuration pattern. Seconds, minutes, and hours default to 0. The remaining fields default to *.
      Parameters:
      zone - timezone ID to use for ZonedDateTime that is supplied to getNextRunTime and skipRun methods. Null indicates to use the system default.

  • Method Details

    • getNextRunTime

      public ZonedDateTime getNextRunTime(LastExecution lastExecutionInfo, ZonedDateTime taskScheduledTime)
      Using the cron schedule, and based on the end of the most recent execution (or absent that, the initial scheduling time), retrieve the next time that the task should run after.
      Specified by:
      getNextRunTime in interface ZonedTrigger
      Parameters:
      lastExecutionInfo - information about the last execution of the task. This value will be null if the task has not yet run.
      taskScheduledTime - the date/time at which the ManagedScheduledExecutorService.schedule method was invoked to schedule the task.
      Returns:
      the date/time after which the next execution of the task should start.
      Throws:
      DateTimeException - if a next time cannot be determined from the cron expression.

    • getZoneId

      public final ZoneId getZoneId()
      Returns the timezone to use for ZonedDateTime that is supplied to the getNextRunTime and skipRun methods.
      Specified by:
      getZoneId in interface ZonedTrigger
      Returns:
      timezone to use for operations on this trigger.

    • daysOfMonth

      public CronTrigger daysOfMonth(int... d)
      Configure the day-of-month cron field, overwriting any previous value for day-of-month.
      Parameters:
      d - one or more day numbers ranging from 1 to 31.
      Returns:
      this instance.

    • daysOfMonth

      public CronTrigger daysOfMonth(String d)
      Configure the day-of-month cron field, overwriting any previous value for day-of-month.
      Parameters:
      d - dayOfMonth cron field. For example, 15,L.
      Returns:
      this instance.

    • daysOfWeek

      public CronTrigger daysOfWeek(DayOfWeek... d)
      Configure the day-of-week cron field, overwriting any previous value for day-of-week.
      Parameters:
      d - one or more days of the week.
      Returns:
      this instance.

    • daysOfWeek

      public CronTrigger daysOfWeek(String d)
      Configure the day-of-week cron field, overwriting any previous value for day-of-week.
      Parameters:
      d - dayOfWeek cron field. For example, MON-FRI,SAT#L.
      Returns:
      this instance.

    • hours

      public CronTrigger hours(int... h)
      Configure the hours cron field, overwriting any previous value for hours.
      Parameters:
      h - one or more hour values ranging from 0 to 23.
      Returns:
      this instance.

    • hours

      public CronTrigger hours(String h)
      Configure the hours cron field, overwriting any previous value for hours.
      Parameters:
      h - hours cron field. For example, 9-17 for 9am to 5pm.
      Returns:
      this instance.

    • minutes

      public CronTrigger minutes(int... m)
      Configure the minutes cron field, overwriting any previous value for minutes.
      Parameters:
      m - one or more minute values ranging from 0 to 59.
      Returns:
      this instance.

    • minutes

      public CronTrigger minutes(String m)
      Configure the minutes cron field, overwriting any previous value for minutes.
      Parameters:
      m - minutes cron field. For example, 5/10 for 10 minute intervals starting at 5 minutes after the hour (:05, :15, :25, :35, :45, :55).
      Returns:
      this instance.

    • months

      public CronTrigger months(Month... m)
      Configure the month cron field, overwriting any previous value for month.
      Parameters:
      m - one or more months.
      Returns:
      this instance.

    • months

      public CronTrigger months(String m)
      Configure the months cron field, overwriting any previous value for months.
      Parameters:
      m - months cron field. For example, SEP-NOV,FEB-MAY.
      Returns:
      this instance.

    • seconds

      public CronTrigger seconds(int... s)
      Configure the seconds cron field, overwriting any previous value for seconds.
      Parameters:
      s - one or more seconds values ranging from 0 to 59.
      Returns:
      this instance.

    • seconds

      public CronTrigger seconds(String s)
      Configure the seconds cron field, overwriting any previous value for seconds.
      Parameters:
      s - seconds cron field. For example, 30.
      Returns:
      this instance.

    • toString

      public String toString()
      Readable representation of the CronTrigger, which displays fields in list form or with the * character for brevity.

      For example, 

      CronTrigger@89abcdef seconds 0, minutes 0, hours 9, *, months 3,6,9,12, SAT#2,SAT#4
      Overrides:
      toString in class Object
      Returns:
      readable representation of the parsed cron expression.

    • next

      protected ZonedDateTime next(ZonedDateTime from)
      Advance to the next date/time according to the cron schedule.
      Parameters:
      from - the date/time from which to compute the next time.
      Returns:
      next date/time according to the cron schedule, or the original time if it matches.