Using the OpenSymphony Quartz Scheduler - Java-Springs

Quartz uses Trigger, Job and JobDetail objects to realize scheduling of all kinds of jobs. For the basic concepts behind Quartz. For convenience purposes, Spring offers a couple of classes that simplify the usage of Quartz within Spring-based applications.

Using the JobDetailBean

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. Let's have a look at an example:

<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 job detail bean has all information it needs to run the job (ExampleJob). 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:

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
}
}

All additional settings from the job detail bean are of course available to you as well.


Using the MethodInvokingJobDetailFactoryBean

Often you just need to invoke a method on a specific object. Using the MethodInvokingJobDetailFactoryBean you can do exactly this:

<bean id="jobDetail"
class="org.springframework.scheduling.quartz.
MethodInvokingJobDetailFactoryBean">
<property name="targetObject" ref="
exampleBusinessObject" />
<property name="targetMethod" value="doIt"/>
</bean>

The above example will result in the doIt method being called on the exampleBusinessObject method (see below):

public class ExampleBusinessObject {
// properties and collaborators
public void doIt() {
// do the actual work
}
}
<bean id="exampleBusinessObject" class="examples.
ExampleBusinessObject"/>

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

By default, Quartz Jobs are stateless, resulting in the possibility of jobs interfering with each other. If you specify two triggers for the same JobDetail, it might be possible that before the first job has finished, the second one will start. If JobDetail classes implement the Stateful interface, this won't happen.

The second job will not start before the first one has finished. To make jobs resulting from the MethodInvokingJobDetailFactoryBean non-concurrent, set the 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 and the SchedulerFactoryBean

We've created job details and jobs. We've also reviewed the convenience bean that allows you to invoke a method on a specific object. Of course, we still need to schedule the jobs themselves. This is done using triggers and a SchedulerFactoryBean. Several triggers are available within Quartz. Spring offers two subclassed triggers with convenient defaults: CronTriggerBean and SimpleTriggerBean.

Triggers need to be scheduled. Spring offers a SchedulerFactoryBean that exposes triggers to be set as properties. SchedulerFactoryBean schedules the actual jobs with those triggers.

Find below a couple of examples:

<bean id="simpleTrigger" class="org.springframework.
scheduling.quartz.SimpleTriggerBean">
<!-- 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.CronTriggerBean">
<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, one running every 50 seconds with a starting delay of 10 seconds and one every morning at 6 AM. To finalize everything, we need to set up the SchedulerFactoryBean:

<bean class="org.springframework.scheduling.
quartz.SchedulerFactoryBean">
<property name="triggers">
<list>
<ref bean="cronTrigger" />
<ref bean="simpleTrigger" />
</list>
</property>
</bean>

More properties are available for the SchedulerFactoryBean for you to set, such as the calendars used by the job details, properties to customize Quartz with, etc.


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