Quartz usage examples and cron expressions in spring boot

Using Quartz with Spring Boot, you can spring-boot-starter-quartzsimplify configuration by adding dependencies. Below is a simple example showing how to use Quartz in a Spring Boot application.

1. First, pom.xmladd spring-boot-starter-quartzdependencies to the file:

<dependencies>
    ...
   dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-quartz</artifactId>
    </dependency>
    ...
</dependencies>

2. Create a Quartz Job class. This class needs to implement org.quartz.Jobthe interface and implement executethe methods:

import org.quartz.Job;
 org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;

public class MyJob implements Job {
    
    
    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
    
    
        System.out.println("Hello, Quartz!");
    }
}

3. Configure Quartz in the Spring Boot configuration class:

import org.quartz.JobDetail;
import org.quartz.SimpleScheduleBuilder;
import org.quartz.Trigger;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.quartz.JobDetailFactoryBean;
import org.springframework.scheduling.quartz.SimpleTriggerFactoryBean;

@Configuration
public class QuartzConfig {
    
    

    @Bean
    public JobDetailFactoryBean myJobDetail() {
    
    
        JobDetailFactoryBean jobDetailFactoryBean = new JobDetailFactoryBean();
        jobDetailFactoryBean.setJobClass(MyJob.class);
        jobDetailFactoryBean.setDurability(true);
        return jobDetailFactoryBean;
    }

    @Bean
    public SimpleTriggerFactoryBean myJobTrigger(JobDetail myJobDetail) {
    
    
        SimpleTriggerFactoryBean trigger = new SimpleTriggerFactoryBean();
        trigger.setJobDetail(myJobDetail);
        trigger.setRepeatInterval(5000); // 每5秒执行一次
        trigger.setRepeatCount(SimpleTrigger.REPEAT_INDEFINITELY); // 无限次重复
        return trigger;
    }
}

In this example, we create a simple Quartz Job that executes every 5 seconds.

Regarding Quartz's cron expression, it is a string containing 6 or 7 fields that is used to define the execution time of the task. The order of the fields is: seconds, minutes, hours, day of month, month, day of week (optional).

Here are some examples of cron expressions:

• 0 0 * * * *: Execution on the hour every hour
• */10 * * * *: Executed every 10 seconds
• 0 0 8-10 * * *: Executed at 8:00, 9:00 and 10:00 every day
• 0 0 6,19 * * *: Executed at 6:00 AM and 7:00 PM every day
• 00/30 8-10 * * *: 8:00, 8:30, 9:00, 9:30, 10:00 and 10:30 every day
• 0 0 9-17 * * MON-FRI: Executed every hour from 9:00 to 17:00 on weekdays
• 0 0 0 25 12 ?: Executed every Christmas at midnight

For more information about Quartz cron expressions, you can refer to the official article: Quartz CronTrigger Tutorial .