Working with Quartz Scheduler in Spring

Quartz Scheduler is used to scheduling of all kinds of jobs. For this it uses Trigger, Job and JobDetail objects

   

 JobDetail objects contain all information needed to run a job. The Spring Framework provides a JobDetailBean that makes the JobDetail more of an actual JavaBean with sensible defaults

For Ex:

<bean name="exampleJob" class="org.springframework.scheduling.quartz.JobDetailBean">

<property name="jobClass" value="example.ExampleJob" />

<property name="jobDataAsMap">

<map>

<entry key="timeout" value="5" />

</map>

</property>

</bean>

The timeout is specified in the job data map. The job data map is available through the JobExecutionContext (passed to you at execution time), but the JobDetailBean also maps the properties from the job data map to properties of the actual job. So in this case, if the ExampleJob contains a property named timeout,the JobDetailBean will automatically apply it.

Ex:

package example;

public class ExampleJob extends QuartzJobBean {

private int timeout;

/**

* Setter called after the ExampleJob is instantiated

* with the value from the JobDetailBean (5)

*/

public void setTimeout(int timeout) {

this.timeout = timeout;

}

protected void executeInternal(JobExecutionContext ctx) throws JobExecutionException {

// do the actual work

}

}

MethodInvokingJobDetailFactoryBean:

Oftenly we need to invoke a method on a specific Class. The

"MethodInvokingJobDetailFactoryBean" can do this exactly. 

Ex Configuration:

<bean id="jobDetail" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">

<property name="targetObject" ref="exampleBusinessObject" />

<property name="targetMethod" value="doIt" />

</bean>

The above example will call the doIt method on the ExampleBusinessObject class.

The class:

public class ExampleBusinessObject {

// properties and collaborators

public void doIt() {

// do the actual work

}

}

Using the MethodInvokingJobDetailFactoryBean, we don't need to create one-line jobs that just invoke a method, and we only need to create the actual business object and wire up the detail object.

By default Quartz jobs are stateless. Since they are stateless there is a possibility of interfering each other.

If we specify 2 triggers for the same JobDetails there is a possibility of starting the second one before first one is Completed.

To avoid this and to make jobs of 'MethodInvokingJobDetailFactoryBean'  

Non-concurrent set 'concurrent' flag to 'false'.

<bean id="jobDetail" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">

<property name="targetObject" ref="exampleBusinessObject" />

<property name="targetMethod" value="doIt" />

<property name="concurrent" value="false" />

</bean>

Wiring up jobs using triggers & the 'SchedulerFactoryBean':

We have created JobDetails and Jobs.

we still needs to schedule the jobs themselves this can be done using 'triggers' and a 'SchedulerFactoryBean'.

There are several triggers are available with in Quartz and Spring Provides 2 Quartz FactoryBean implementations with convenient defaults

CronTriggerFactoryBean

SimpleTriggerFactoryBean.

Triggers need to be Scheduled.For this Spring offers a 'SchedulerFactoryBean' that exposes triggers to be set as properties.

SchedulerFactoryBean schedules the actual jobs with those triggers.

Ex. Configurations:

<bean id="simpleTrigger" class="org.springframework.scheduling.quartz.SimpleTriggerFactoryBean">

<!-- see the example of method invoking job above -->

<property name="jobDetail" ref="jobDetail" />

<!-- 10 seconds -->

<property name="startDelay" value="10000" />

<!-- repeat every 50 seconds -->

<property name="repeatInterval" value="50000" />

</bean>

<bean id="cronTrigger" class="org.springframework.scheduling.quartz.CronTriggerFactoryBean">

<property name="jobDetail" ref="exampleJob" />

<!-- run every morning at 6 AM -->

<property name="cronExpression" value="0 0 6 * * ?" />

</bean>

Now we've set up two triggers, 

First one running every 50 seconds with a starting delay of 10 seconds and

Second one runs every morning at 6 AM. And Finally we need to set up the

SchedulerFactoryBean:

<bean class="org.springframework.scheduling.quartz.SchedulerFactoryBean">

<property name="triggers">

<list>

<ref bean="cronTrigger"/>

<ref nean="simpleTrigger"/>

</list>

</property>

</bean>

there are some more properties to use.