Schedule tasks in Spring 3 Using @Scheduled

Explaining @Scheduled annotation

This annotation is used for task scheduling. The trigger information needs to be provided along with this annotation. You can use the properties fixedDelay/fixedRate/cron to provide the triggering information.

1. fixedRate makes Spring run the task on periodic intervals even if the last invocation may be still running.
2. fixedDelay specifically controls the next execution time when the last execution finishes.
3. cron is a feature originating from Unix cron utility and has various options based on your requirements.

Example usage can be as below:

@Scheduled(fixedDelay =30000)
public void demoServiceMethod () {... }

@Scheduled(fixedRate=30000)
public void demoServiceMethod () {... }

@Scheduled(cron="0 0 * * * *")
public void demoServiceMethod () {... }

To use @Scheduled in your spring application, you must first define below xml namespace and schema location definition in your application-config.xml file.

xmlns:task="http://www.springframework.org/schema/task"

http://www.springframework.org/schema/task

http://www.springframework.org/schema/task/spring-task-3.0.xsd

Above additions are necessary because we will be using annotation based configurations. Now add below definition to enable annotations.

 

Next step is to create a class and a method inside the class like below:

public class DemoService
{
 @Scheduled(cron="*/5 * * * * ?")
 public void demoServiceMethod()
 {
  System.out.println("Method executed at every 5 seconds. Current time is :: "+ new Date());
 }
}

Using @Scheduled annotation would in turn make Spring container understand that the method underneath this annotation would run as a job. Remember that the methods annotated with @Scheduled should not have parameters passed to them. They should not return any values too. If you want the external objects to be used within your @Scheduled methods, you should inject them into the DemoService class using autowiring rather than passing them as parameters to the @Scheduled methods.

And application configuration will look like this:
 

< ?xml  version="1.0" encoding="UTF-8"?>