如何在Java中使用Quartz实现定时任务？

Scheduler 每次执行，都会根据JobDetail创建一个新的Job实例，这样就可以规避并发访问的问题（jobDetail的实例也是新的）

Quzrtz 定时任务默认都是并发执行，不会等待上一次任务执行完毕，只要间隔时间到就会执行，如果定时任务执行太长，会长时间占用资源，导致其它任务堵塞

@DisallowConcurrentExecution: job类上，禁止并发地执行同一个job定义 (JobDetail定义的)的多个实例。

• scheduler：可以理解为定时任务的工作容器或者说是工作场所，所有定时任务都是放在里面工作，可以开启和停止。

• trigger：可以理解为是定时任务任务的工作规则配置，例如说，没个几分钟调用一次，或者说指定每天那个时间点执行。

• jobDetail：定时任务的信息，例如配置定时任务的名字，群组之类的。

• job：定时任务的真正的业务处理逻辑的地方。

简单示例

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();
        }

    }

}

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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());
    }
}

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usingJobData

通过 usingJobData 往定时任务中传递参数

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();
        }

    }

}

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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"));
    }
}

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通过属性赋值

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();
        }

    }

}

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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);
    }
}

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非并发执行

@DisallowConcurrentExecution job类上，禁止并发地执行同一个job定义 (JobDetail定义的)的多个实例。

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();
        }
    }
}

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@PersistJobDataAfterExecution

持久化JobDetail中的JobDataMap（对 trigger 中的 datamap 无效），如果一个任务不是

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"));

    }
}

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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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