Brief introduction
Unix Cron as a tool, has been around for a long time, for the realization of task scheduling function. CronTrigger classes based on Cron come.
CronTrigger
CronTriggers often more useful than SimpleTrigger, if you need a calendar based on the concept, rather than SimpleTrigger fully specified time interval, schedule recurring launch work.
CronTrigger, you can specify a timetable trigger such as "every Friday at noon," or "every weekday at 9:30" or even "every 5 minutes 9:00 and 10:00 am every Monday, Wednesday, Friday." .
Even so, as SimpleTrigger, CronTrigger have effect when the startTime specified schedule, the specified timetable, should stop (optional) end time.
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Cron Expressions
Quartz Cron expression defined using similar rules of time Linux, Cron expression of six or seven times separated by white space fields.
According to the order to
seconds (0 to 59)
minutes (0 to 59)
hours (0 to 23)
days (month) (0 to 31, but you need to consider the number of days you months)
months (0 to 11)
days (week) (1 ~ 7 1 = SUN or the SUN, the MON, the TUE, WEDs, the THU, the FRI, the SAT)
7. The Year (1970-2099)
in which each element can be a value (e.g., 6), a continuum (9-12 ), a time interval (8-18 / 4) (/ indicates every 4 hours), a list (1,3,5), wildcard. As the "day of the month" and "date of the week," these two elements are mutually exclusive, and must be for one of the settings?.
00 10,14,16 * *? 10 am every day, 14:00, 4 point
? 0 0/30 * * 9-17 inward nine to five hours every half hour
? 0 0 12 * WED 12:00 every Wednesday expressed
some sub-expressions can contain a range or list
such as: sub-expressions ( days (weeks)) can be "MON-FRI", "MON, WED, FRI", "MON-WED, SAT,"
"*" character represents all possible values
Therefore, the "*" in the sub-expression (month) in represents the meaning of each month, "*" in the sub-expression (days (weeks)) represent each day of the week
"/" character is used to specify the value of the increment
example: in sub-expressions (minutes) in the "0 / 15 "starts from 0 minutes, every 15 minutes
in the sub-expression (minutes) in the" 3/20 "indicates that from the first three minutes, every 20 minutes (and it" 3,23,43 ") as meaning
"?" Character is used only day (month) and day (week) two sub-expression that do not specify a value
when one of the two sub-expressions which are assigned a value in the future, in order to avoid conflict, you need to express another child style value is set to "?" ,
"L" character is used only day (month) and day (week) two sub-expression, it is the word "abbreviation last" of
it meaning in the two sub-expressions are different of.
Day (month) sub-expression, "L" represents the last day of the month
in the day (week) from the expression, "L" represents the last day of the week, which is the SAT
If there are specific in the "L" before content, it has the other meanings
such as: "6L" the reciprocal of the sixth day of the month, "FRIL" represents the best Friday of the month
Note: when using the "L" parameter, do not specify the list or range, this can cause problems because
Cron expression Example:
Executed once every 5 seconds: * / 5 * * * *?
Executed once every minute: 0 * / 1 * * *?
23:00 executed once a day: 0023 * *?
1:00 executed once a day: 001 * *?
Monthly No. 1 1:00 execution time: 0011 *?
The last day of each month 23:00 executed once: 0 0 23 L *?
Weekly Sunday 1:00 to implement once: 0 0 1 * L?
In 26 points, 29 points, 33 points is performed once: 0 26,29,33 * * *?
Daily 0:00, 13:00, 18:00, 21:00 executed once: 00 0,13,18,21 * *?