[JAVA] Spring Boot tutorial task schedule

I created a program to execute tasks regularly by referring to the official Spring boot tutorial (Task Schedule).

environment

Apache Maven 3.6.3 OS: macOS Mojave version 10.14.6 Text editor: VSCode Java: 11.0.2

Create

First, open Spring Initializr and create a foundation with the following contents.

Unzip the resulting zip file and open it in an editor.

Add the following dependency to pom.xml.

<dependency>
  <groupId>org.awaitility</groupId>
  <artifactId>awaitility</artifactId>
  <version>3.1.2</version>
  <scope>test</scope>
</dependency>

Awaitility is a * library that provides a simple domain-specific language (DSL) for asynchronous system testing *. (From Introduction to Awaitility)

Create a ScheduledTasks.java file under src / main / java / com / example / schedulingtasks.

The contents are as follows.

ScheduledTasks.java

package com.example.schedulingtasks;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class ScheduledTasks {

	private static final Logger log = LoggerFactory.getLogger(ScheduledTasks.class);

	private static final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");

	@Scheduled(fixedRate = 5000)
	public void reportCurrentTime() {
		log.info("The time is now {}", dateFormat.format(new Date()));
	}
}

fixedRate specifies the method call interval, measured from the start time of each call. Other options, such as fixedDeley, specify the interval between calls from task completion.

@Scheduled Run the task periodically. You can choose from a variety of options (table below). Specify the execution cycle with the Scheduled annotation for the task you want to execute periodically. This annotation can only be specified for methods that take no arguments. (It does not result in a compile error, but an exception occurs at runtime.)

This time I'll run the task every 5 seconds with fixedRate.

You can also use (cron = "...") for more advanced settings.

Logger and LoggerFactory are for outputting the result to console. You can display the log by specifying the class in the argument of LoggerFactory.getLogger ().

Then add the code to the automatically created SchedulingTasksApplication.java file under src / main / java / com / example / schedulingtasks /.

The contents are as follows.

SchedulingTasksApplication.java

package com.example.schedulingtasks;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class SchedulingTasksApplication {

	public static void main(String[] args) {
		SpringApplication.run(SchedulingTasksApplication.class);
	}
}

@SpringBootApplication This is a convenient annotation that works as an annotation for three. It contains the following three annotations.

@Configuration You can register additional beans in the context and import additional configuration classes.

@Bean It is for returning the class instantiated by the method that describes @Bean.

@EnableAutoConfiguration Enables the Spring Boot automatic configuration mechanism.

@ComponentScan It looks for other components, settings, etc. in the package and tells Spring to find the controller.

@EnableScheduling Enable the schedule.

Execute

The code is now complete. I will execute it with the following command at once.

./mvnw spring-boot:run

The task is running every 5 seconds.

It was easy to create without adding any dependencies!