How to use Quartz to implement scheduled tasks in Java?

Scheduler will create a new Job instance based on JobDetail every time it is executed, so as to avoid the problem of concurrent access (the instance of jobDetail is also new)

Quzrtz scheduled tasks are executed concurrently by default, no It will wait for the last task to be executed, and it will be executed as long as the interval is up. If the scheduled task is executed for too long, it will occupy resources for a long time and cause other tasks to be blocked.

@DisallowConcurrentExecution: On the job class, concurrent execution is prohibited Multiple instances of the same job definition (defined by JobDetail).

• scheduler: It can be understood as a work container or workplace for scheduled tasks. All scheduled tasks are placed in it and can be opened and stop.

• trigger: It can be understood as the work rule configuration of a scheduled task. For example, it is called every few minutes, or it is specified to be executed at that time point every day.

• jobDetail: Scheduled task information, such as configuring the name of the scheduled task, group, etc.

• job: The place where the real business processing logic of scheduled tasks is located.

Simple example

TestClient.Java

import org.quartz.*;
import org.quartz.impl.StdSchedulerFactory;

public class TaskClient {

    public static void main(String[] args) {
        JobDetail jobDetail = JobBuilder.newJob(TaskJob.class)
                .withIdentity("job1", "group1")  //设置JOB的名字和组
                .build();

        Trigger trigger = TriggerBuilder.newTrigger()
                .withIdentity("trigger1", "trigger1")
                .startNow()
                .withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1)
                        .repeatForever())
                .build();
        try {
            Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
            scheduler.scheduleJob(jobDetail,trigger);
            scheduler.start();
        } catch (SchedulerException ex) {
            ex.printStackTrace();
        }

    }

}

TaskJob.Java

import cn.hutool.core.date.DateUtil;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;

public class TaskJob implements Job {
    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
        System.out.println("TaskJob => " + DateUtil.now());
    }
}

##usingJobData

Pass parameters to scheduled tasks through usingJobData

import org.quartz.*;
import org.quartz.impl.StdSchedulerFactory;

public class TaskClient {

    public static void main(String[] args) {
        JobDetail jobDetail = JobBuilder.newJob(TaskJob.class)
                .withIdentity("job1", "group1")
                .usingJobData("job","jobDetail1.JobDataMap.Value")
                .build();

        Trigger trigger = TriggerBuilder.newTrigger()
                .withIdentity("trigger1", "trigger1")
                .usingJobData("trigger","trigger.JobDataMap.Value")
                .startNow()
                .withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1)
                        .repeatForever())
                .build();
        try {
            Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
            scheduler.scheduleJob(jobDetail,trigger);
            scheduler.start();
        } catch (SchedulerException ex) {
            ex.printStackTrace();
        }

    }

}

TaskJob.java

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

public class TaskJob implements Job {
    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        JobDataMap jobDataMap = context.getJobDetail().getJobDataMap();
        JobDataMap triggerMap = context.getTrigger().getJobDataMap();
        JobDataMap mergeMap = context.getMergedJobDataMap();


        System.out.println("jobDataMap => " + jobDataMap.getString("job"));
        System.out.println("triggerMap => " + triggerMap.getString("trigger"));
        System.out.println("mergeMap => " + mergeMap.getString("trigger"));
    }
}

Assign values ​​through attributes

import org.quartz.*;
import org.quartz.impl.StdSchedulerFactory;

public class TaskClient {

    public static void main(String[] args) {
        JobDetail jobDetail = JobBuilder.newJob(TaskJob.class)
                .withIdentity("job1", "group1")
                .usingJobData("job","jobDetail1.JobDataMap.Value")
                .usingJobData("name","jobDetail1.name.Value") //通过 setName 自动赋值
                .build();

        Trigger trigger = TriggerBuilder.newTrigger()
                .withIdentity("trigger1", "trigger1")
                .usingJobData("trigger","trigger.JobDataMap.Value")
                .usingJobData("name","trigger.name.Value")  //如果 Trigger 有值，会覆盖 JobDetail
                .startNow()
                .withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1)
                        .repeatForever())
                .build();
        try {
            Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
            scheduler.scheduleJob(jobDetail,trigger);
            scheduler.start();
        } catch (SchedulerException ex) {
            ex.printStackTrace();
        }

    }

}

import org.quartz.*;

public class TaskJob implements Job {

    private String name;

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {

        System.out.println("name => " + name);
    }
}

Non-concurrent execution

@DisallowConcurrentExecution job class prohibits concurrent execution of multiple instances of the same job definition (JobDetail definition).

import cn.hutool.core.date.DateUtil;
import org.quartz.*;

@DisallowConcurrentExecution
public class TaskJob implements Job {

    @Override
    public void execute(JobExecutionContext context) {
        System.out.println("Time => " + DateUtil.now());
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

@PersistJobDataAfterExecution

Persistent JobDataMap in JobDetail (invalid for datamap in trigger), if a task is not

import cn.hutool.core.date.DateUtil;

import org.quartz.*;

//持久化JobDetail中的JobDataMap（对 trigger 中的 datamap 无效），如果一个任务不是
@PersistJobDataAfterExecution
public class TaskJob implements Job {

    @Override
    public void execute(JobExecutionContext context) {
        JobDataMap triggerMap = context.getJobDetail().getJobDataMap();
        triggerMap.put("count", triggerMap.getInt("count") + 1);
        System.out.println("Time => " + DateUtil.now() + " count =>" + triggerMap.getInt("count"));

    }
}

Client

import org.quartz.*;
import org.quartz.impl.StdSchedulerFactory;

public class TaskClient {

    public static void main(String[] args) {
        JobDetail jobDetail = JobBuilder.newJob(TaskJob.class)
                .withIdentity("job1", "group1")
                .usingJobData("job","jobDetail1.JobDataMap.Value")
                .usingJobData("name","jobDetail1.name.Value") //通过 setName 自动赋值
                .usingJobData("count",0) //通过 setName 自动赋值
                .build();

        Trigger trigger = TriggerBuilder.newTrigger()
                .withIdentity("trigger1", "trigger1")
                .usingJobData("trigger","trigger.JobDataMap.Value")
                .usingJobData("name","trigger.name.Value")  //如果 Trigger 有值，会覆盖 JobDetail
                .startNow()
                .withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(1)
                        .repeatForever())
                .build();
        try {
            Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
            scheduler.scheduleJob(jobDetail,trigger);
            scheduler.start();
        } catch (SchedulerException ex) {
            ex.printStackTrace();
        }

    }

}

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