Spring Cron表达式的含义“* / 5 * * * *？”

Question

I used spring scheduler with cron expression

*/5 * * * * ?

(for every 5 seconds) . It's worked for last one month, suddenly it's stopped in last two days.

After Restarting server again it's working fine.

Is there any difference between

*/5 * * * * ?
*/5 * * * * *

? it's based on any month basis.

So what is the meaning of ? here. Want to know the reason why it's stopped?

Thanks in Advance.

Answer 1

Here "

*

means all values . For example, dayofmonth="*" means run the process every day.

"?"

is used only for dayofmonth and dayofweek attribute

and means "without regard to this value" For example, hours="12" dayofweek="MON-FRI" dayofmonth="?" means "Run at noon every weekday (without regard to the day of the month)".

","

separates multiple values. For example, dayofweek="MON,FRI" means every Monday and Friday. Do not includes spaces after the comma.

"/"

specifies increments. For example, minutes="0/15" means start at minute 0 and run every 15 minutes.

"L" is used only for dayofmonth and dayofweek and means "the last day of the month/week".

Answer 2

From the Quartz documentation :

The '?' character is allowed for the day-of-month and day-of-week fields. It is used to specify “no specific value”. This is useful when you need to specify something in one of the two fields, but not the other. See the examples below (and CronTrigger JavaDoc) for clarification.