Quartz Job Scheduling Framework

Chapter 5. Cron Triggers and More

We promised in the last chapter that we would spend more time on the Quartz CronTrigger, and we won’t let you down. SimpleTriggers are fine for jobs that need to execute at a specified millisecond in time, but if your jobs require more complex execution schedules, you need the power and flexibility that CronTriggers offer.

Quick Lesson in Cron

The idea of cron comes from the UNIX world. In UNIX, cron is a daemon that runs in the background and is responsible for all timed events. Although Quartz shares nothing with UNIX cron other than the name and similar expression syntax, it’s worth spending a couple of paragraphs to understand the history behind cron. Our goal here is not to confuse UNIX cron expressions ...