Quartz 之 JobExecutionContext 解读

谁借莪１个温暖的怀抱￠ 2023-07-02 05:29 30阅读 0赞

项目地址：   [https://github.com/yuleiqq/quartz\_example/tree/master/quartz\_study][https_github.com_yuleiqq_quartz_example_tree_master_quartz_study]

查看源码注释可以得知：

JobExecutionContext 是一个包含了各种上下文信息的句柄，指向执行中的JobDetail 实例 和 执行完成的Trigger实例.

JobExecutionContext中有一个简便的方法可以获取执行上下文中的JobDataMap , 它是JobDetail 中的JobDataMap 和 Trigger 中的JobDataMap 的合并，后者的JobDataMap 会覆盖前者相同名称的值.

**注意： 不要期望通过这个返回的JobDataMap 的set 方法设置 某个值 持久化到作业自身的JobDataMap ，即使 有@PersistJobDataAfterExecution .**

试图更改此映射的内容通常会导致IllegalStateException 异常.

public JobDataMap getMergedJobDataMap();

我们看下如下例子.

package com.example04;
    
            import org.quartz.*;
            import org.quartz.impl.StdSchedulerFactory;
    
    /**
     * 1442554244
     * JobExecutionContext例子
     **/
    
    public class CronTriggerExample {
    
        public void run () throws SchedulerException {
    
            //实例化调度器
            Scheduler scheduler  =StdSchedulerFactory.getDefaultScheduler();
    
            //实例化job
            JobDetail job1 = JobBuilder.newJob(SimpleJob.class)
                    .withIdentity("job1","group1")
                    //设置jobDetail值
                    .usingJobData("name","tom")
                    .usingJobData("email","123@qq.com")
                    // 当job 没有绑定trigger时，继续保存在调度器中
                    .storeDurably()
                    .build();
    
            //若有相同名称的job ，是否替换，否则抛出异常, 使用这个方法，必须保证 isDurable=true
            scheduler.addJob(job1,false);
    
            //定义Contrigger
            CronTrigger cronTrigger1 = TriggerBuilder.newTrigger()
                    .withIdentity("trigger1","group1")
                    //设置JobDatail值
                    .usingJobData("email","456@qq.com")
                    .withSchedule(CronScheduleBuilder.cronSchedule(" 0/5 * * * * ? "))
                    .forJob(job1)
                    .build();
    
            scheduler.scheduleJob(cronTrigger1);
    
            scheduler.start();
    
        }
    
        public static void main(String[] args) throws SchedulerException {
            CronTriggerExample example = new CronTriggerExample();
            example.run();
    
        }
    }

package com.example04;
    
    import org.quartz.*;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import java.util.Date;
    
    /**
     * @author  yulei
     */
    
    public class SimpleJob implements Job {
    
        private static Logger log = LoggerFactory.getLogger(SimpleJob.class);
    
        public SimpleJob() {
    
        }
    
        public void execute(JobExecutionContext context) throws JobExecutionException {
    
            JobKey jobKey = context.getJobDetail().getKey();
    
            JobDataMap jobDataMap = context.getMergedJobDataMap();
    
            log.info("name: "+jobDataMap.getString("name")+", email: "+jobDataMap.getString("email"));
            log.info("SimpleJob says: " + jobKey + " executing at " + new Date());
        }
    
    }

打印内容如下：

INFO] 27 一月 11:52:32.084 上午 main [org.quartz.impl.StdSchedulerFactory]
    Using default implementation for ThreadExecutor
    
    [INFO] 27 一月 11:52:32.109 上午 main [org.quartz.core.SchedulerSignalerImpl]
    Initialized Scheduler Signaller of type: class org.quartz.core.SchedulerSignalerImpl
    
    [INFO] 27 一月 11:52:32.109 上午 main [org.quartz.core.QuartzScheduler]
    Quartz Scheduler v.2.3.0 created.
    
    [INFO] 27 一月 11:52:32.110 上午 main [org.quartz.simpl.RAMJobStore]
    RAMJobStore initialized.
    
    [INFO] 27 一月 11:52:32.111 上午 main [org.quartz.core.QuartzScheduler]
    Scheduler meta-data: Quartz Scheduler (v2.3.0) 'MyScheduler' with instanceId 'NON_CLUSTERED'
      Scheduler class: 'org.quartz.core.QuartzScheduler' - running locally.
      NOT STARTED.
      Currently in standby mode.
      Number of jobs executed: 0
      Using thread pool 'org.quartz.simpl.SimpleThreadPool' - with 20 threads.
      Using job-store 'org.quartz.simpl.RAMJobStore' - which does not support persistence. and is not clustered.
    
    
    [INFO] 27 一月 11:52:32.112 上午 main [org.quartz.impl.StdSchedulerFactory]
    Quartz scheduler 'MyScheduler' initialized from default resource file in Quartz package: 'quartz.properties'
    
    [INFO] 27 一月 11:52:32.112 上午 main [org.quartz.impl.StdSchedulerFactory]
    Quartz scheduler version: 2.3.0
    
    [INFO] 27 一月 11:52:32.135 上午 main [org.quartz.core.QuartzScheduler]
    Scheduler MyScheduler_$_NON_CLUSTERED started.
    
    [INFO] 27 一月 11:52:35.007 上午 MyScheduler_Worker-1 [com.example04.SimpleJob]
    name: tom, email: 456@qq.com
    
    [INFO] 27 一月 11:52:35.011 上午 MyScheduler_Worker-1 [com.example04.SimpleJob]
    SimpleJob says: group1.job1 executing at Mon Jan 27 11:52:35 CST 2020

由次可以看出，触发器中的JobDataMap 会覆盖JobDetail 中相同名称的key 的value 。

[https_github.com_yuleiqq_quartz_example_tree_master_quartz_study]: https://github.com/yuleiqq/quartz_example/tree/master/quartz_study