Spring Framework provides a mechanism for scheduling purpose: Spring Scheduler. The tutorial will introduce about how to schedule tasks with Spring.
I. Technology for Spring Scheduler tutorial
– Java 1.8
– Maven: 3.3.9
– Editor: Spring Tool Suite – Version 3.7.3.RELEASE
– Spring Boot: Version: 3.8.0.RELEASE
II. Overview
1. Structure of project
2. Step to Do
– Create Spring Boot project
– Create Create Scheduler Task
– Enable Spring Scheduler
– Run & Check result
III. Practices
1. Create Spring Boot project
Open Spring Tool Suite, on main menu, Choose File->New->Spring Starter Project.
Input needed information about project as below images:
Press Next button then press Finish. Spring Boot project is created.
2. Create Create Scheduler Task
Create a simple component class with 3 scheduled tasks defined by 3 methods:
– @Scheduled(fixedRate = 2000)
public void timeReport(): the method will be invoked each 2 seconds
– @Scheduled(initialDelay=1000, fixedRate = 2000)
public void initDelayTimeReport(): the method will be delay 1 second & will be invoked each 2 seconds after the first time
– @Scheduled(cron = “*/5 * * * * *”)
public void cronTimeReport(): using cron-expression for define a scheduled task that will be invoked for each 5 seconds.
– @Scheduled: An annotation that marks a method to be scheduled. Exactly one of the cron(), fixedDelay(), or fixedRate() attributes must be specified.
Code details:
import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
@Component
public class ScheduledTasks {
private static final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
@Scheduled(fixedRate = 2000)
public void timeReport() {
System.out.println("[TimeReport] Now: " + dateFormat.format(new Date()));
}
@Scheduled(initialDelay=1000, fixedRate = 2000)
public void initDelayTimeReport() {
System.out.println("[InitDelayTimeReport] Now: " + dateFormat.format(new Date()));
}
@Scheduled(cron = "*/5 * * * * *")
public void cronTimeReport() {
System.out.println("[CronTimeReport] Now: " + dateFormat.format(new Date()));
}
}
3. Enable Spring Scheduler
Using @EnableScheduling in main Spring class: Enables Spring’s scheduled task execution capability, similar to functionality found in Spring’s
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
@SpringBootApplication
@EnableScheduling
public class SpringSchedulerApplication {
public static void main(String[] args) {
SpringApplication.run(SpringSchedulerApplication.class, args);
}
}
4. Run & Check result
– Compile sourcecode:
clean install
– Run project with Spring mode: Spring Boot App.
– Log:
[TimeReport] Now: 16:01:13 2016-08-21 16:01:13.938 INFO 5292 --- [ main] c.s.s.SpringSchedulerApplication : Started SpringSchedulerApplication in 4.827 seconds (JVM running for 7.839) [InitDelayTimeReport] Now: 16:01:14 [CronTimeReport] Now: 16:01:15 [TimeReport] Now: 16:01:15 [InitDelayTimeReport] Now: 16:01:16 [TimeReport] Now: 16:01:17 [InitDelayTimeReport] Now: 16:01:18 [TimeReport] Now: 16:01:19 [CronTimeReport] Now: 16:01:20 [InitDelayTimeReport] Now: 16:01:20 [TimeReport] Now: 16:01:21 [InitDelayTimeReport] Now: 16:01:22 [TimeReport] Now: 16:01:23 [InitDelayTimeReport] Now: 16:01:24 [CronTimeReport] Now: 16:01:25 [TimeReport] Now: 16:01:25 [InitDelayTimeReport] Now: 16:01:26
