how to change shceduler times in spring

How to change scheduler times in Spring

 

Imagine that you have scheduler but you want to change time at runtime. What Can you do? Off-course there are ways do solve the problem. So In this article I will write how to implement Trigger interface that is located to the following package: org.springframework.scheduling in the spring-context project.

1. First off all, let's create interface for our logic:

2. In Spring we have org.springframework.scheduling.Trigger interface:

So we can write our own implementation. It's very simple. We should just overwrite nextExecutionTime(_) method.  Something like that:

	import org.springframework.scheduling.TaskScheduler;
	import org.springframework.scheduling.Trigger;
	import org.springframework.scheduling.TriggerContext;
	import java.util.Date;
	import java.util.concurrent.ScheduledFuture;
	public class CustomDynamicSchedule extends DynamicSchedule implements Trigger {
	private TaskScheduler taskScheduler;
	private ScheduledFuture<?> schedulerFuture;
	/**
	* milliseconds
	*/
	private long delayInterval;
	public CustomDynamicSchedule(TaskScheduler taskScheduler) {
	this.taskScheduler = taskScheduler;
	}
	@Override
	public void increaseDelayInterval(Long delay) {
	if (schedulerFuture != null) {
	schedulerFuture.cancel(true);
	}
	this.delayInterval += delay;
	schedulerFuture = taskScheduler.schedule(() -> { }, this);
	}
	@Override
	public void decreaseDelayInterval(Long delay) {
	if (schedulerFuture != null) {
	schedulerFuture.cancel(true);
	}
	this.delayInterval += delay;
	schedulerFuture = taskScheduler.schedule(() -> { }, this);
	}
	@Override
	public void delay(Long delay) {
	if (schedulerFuture != null) {
	schedulerFuture.cancel(true);
	}
	this.delayInterval = delay;
	schedulerFuture = taskScheduler.schedule(() -> { }, this);
	}
	@Override
	public Date nextExecutionTime(TriggerContext triggerContext) {
	Date lastTime = triggerContext.lastActualExecutionTime();
	return (lastTime == null) ? new Date() : new Date(lastTime.getTime() + delayInterval);
	}
	}

view raw CustomDynamicSchedule.java hosted with ❤ by GitHub

3. Now we can write configuration.

	@Configuration
	public class DynamicSchedulerConfig {
	@Bean
	public DynamicSchedule getDinamicScheduler() {
	ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler();
	threadPoolTaskScheduler.setPoolSize(1);
	threadPoolTaskScheduler.initialize();
	return new DynamicSchedule(threadPoolTaskScheduler);
	}
	}

view raw DynamicSchedulerConfig.java hosted with ❤ by GitHub

In this example we just choose ThreadPoolTaskScheduler that is child ofTaskScheduler interface.


4. So what is the next? Let's see how to use our scheduler. Everything is simple:

	@Autowired
	private DynamicSchedule dynamicSchedule;
	@Scheduled(fixedDelay=5000)
	public void change() {
	dynamicSchedule.increaseDelay(1000);
	}

view raw DynamicScheduleExample.java hosted with ❤ by GitHub

That's it!

Goodbye!
Have good day!