Mark S. Kolich: Mobile (mobi.koli.ch)

Spring Timer's are great if you need a job or task to run on a fixed interval. For example, if you need a bean to wake up and run itself every 30-minutes. But what if you need finer control over the scheduling of a timer? Say you need a job to run every morning at 3AM, regardless of when the JVM is started. Or, say you need a bean to run "every half hour between the hours of 8 AM and 10 AM on the 5th and 20th of every month." You won't get that type of granular control with a straight-up Spring Timer.

Meet Quartz, a full-featured, open source job scheduling service that can be integrated with, or used along side virtually any Java EE or Java SE application. Similar to a native UNIX Cron job, Quartz lets you define powerful CronExpression's that give you very precise control over when a job or task is started and on what interval.

Setting up Quartz with your Spring powered web-application is easy.

1 - Download Quartz

The latest Quartz libraries are available here. Download them, and add to your build-path and build-files accordingly.

2 - Add Beans to Your applicationContext.xml

In your applicationContext.xml, add the necessary beans:

<!-- this is the bean we're going to run on a schedule
      with Quartz; we'll call it UpdaterOnScheduleExecutor.
      The class is com.kolich.app.beans.UpdaterBean -->
<bean id="UpdaterOnScheduleExecutor"
  class="com.kolich.app.beans.UpdaterBean"
  init-method="init"
  depends-on="AnotherBean">
  <property name="someProperty" value="/WEB-INF/something" />
</bean>

<!-- quartz stuff below -->

<!-- UpdaterOnScheduleJobDetail defines a bean that points to
       UpdaterOnScheduleExecutor and says to call its execute()
       method when the trigger is fired -->
<bean id="UpdaterOnScheduleJobDetail"
  class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
  <property name="targetObject" ref="UpdaterOnScheduleExecutor"/>
  <!-- the method to call inside of
        com.kolich.app.beans.UpdaterBean -->
  <property name="targetMethod" value="execute"/>
</bean>

<!-- here's where we use the Cron like scheduling expression
      to define when the bean is run. -->
<bean id="UpdaterOnScheduleJob"
  class="org.springframework.scheduling.quartz.CronTriggerBean">
  <property name="jobDetail" ref="UpdaterOnScheduleJobDetail" />
  <!-- run every morning at 3AM -->
  <property name="cronExpression" value="0 0 3 * * ?" />
</bean>

<!-- the scheduler factory is what does the work to setup
       the triggers -->
<bean class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
  <property name="triggers">
      <list>
          <ref bean="UpdaterOnScheduleJob" />
      </list>
  </property>
</bean>

Note that you can add as many jobs/triggers as desired to the Quartz SchedulerFactoryBean.

3 - Sample Cron Expressions

Here are some other sample cronExpression's you might enjoy (I borrowed these from the Quartz trigger tutorial) ...

Fires every five minutes:

"0 0/5 * * * ?"

Fires every 5 minutes, at 10 seconds after the minute:

"10 0/5 * * * ?"

Fires at 10:30, 11:30, 12:30, and 13:30, on every Wednesday and Friday:

"0 30 10-13 ? * WED,FRI"

Fires every half hour between the hours of 8 am and 10 am on the 5th and 20th of every month:

"0 0/30 8-9 5,20 * ?"

Enjoy!

HOWTO: Scheduling Cron Style Timers and Jobs with Spring and Quartz