Cron

Cron scheduled tasks are similar to the crontab tasks with Linux systems. However, crontab is not support distributed scheduling.

Expression

There is a slight difference between Cron scheduled tasks and crontab time expressions. The smallest granularity of crontab is minute, while the smallest granularity of Cron scheduled tasks is second. Cron time expressions are by default identical to Java (Quartz).

Cron expressions are slight different from crontab.Crontab unit is minute,but cron expression unit is second, and it is exactly the same as Java(Quartz).

Cron expressions as follows:

Explanation:
Java(Quartz)
*    *    *    *    *    *    *
-    -    -    -    -    -    -
|    |    |    |    |    |    |
|    |    |    |    |    |    + year [optional]
|    |    |    |    |    +----- day of week (1 - 7) sun,mon,tue,wed,thu,fri,sat
|    |    |    |    +---------- month (1 - 12) OR jan,feb,mar,apr ...
|    |    |    +--------------- day of month (1 - 31)
|    |    +-------------------- hour (0 - 23)
|    +------------------------- min (0 - 59)
+------------------------------ second (0 - 59)

Examples:

# Every hour
0 0 */1 * * ?

# Every minute
0 */1 * * * ?

# The last day of every month
0 0 18 L * ?  

danger

Cron expressions must less than 60 seconds(Recommend second delay), otherwise it case performance problem.