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This article introduces the knowledge of "how to use Java task scheduling framework Quartz". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Compared to Timer, Quartz adds a lot of features to Quartz:

Persistent jobs-that is, to maintain the state of scheduling timing

Job management-effective management of scheduled jobs

1 、 Quartz

1.1 introduction of dependency

Org.quartz-scheduler quartz 2.3.2 org.quartz-scheduler quartz-jobs 2.3.21.2 getting started

Task: execute the task class 10 times with an interval of 3 seconds each time.

Task class, you need to implement the Job interface

Package com.sugar.quartz.utils;import org.quartz.Job;import org.quartz.JobExecutionContext;import org.quartz.JobExecutionException;import java.text.SimpleDateFormat;import java.util.Date;/** * function description: task * * @ author XiaoNianXin * @ date 20:52 on 2021-12-13 * / public class HelloJob implements Job {@ Override public void execute (JobExecutionContext context) throws JobExecutionException {/ / get the current time and format Date date = new Date () SimpleDateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); String dateSrting = format.format (date); / / Business function simulates System.out.println ("start backup database, time:" + dateSrting);}} timer class

Package com.sugar.quartz.utils;import org.quartz.*;import org.quartz.impl.StdSchedulerFactory;/** * function description: timer configuration * * @ author XiaoNianXin * @ date 21:08 on 2021-12-13 * / public class HelloSchedulerDemo {public static void main (String [] args) throws SchedulerException {/ / 1, Scheduler-get scheduling instance from factory Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler () / / 2. Task instance-Task object JobDetail job = JobBuilder.newJob (HelloJob.class) .withIdentity ("job1", "group1") / / Task name, group name .build () / / 3, trigger-controls the number of execution times and execution time Trigger trigger = TriggerBuilder.newTrigger () .withIdentity ("trigger1", "group1") / / ditto .startNow () / / start .withschedule (SimpleScheduleBuilder.simpleSchedule ()) immediately. WithIntervalInSeconds (3). WithRepeatCount (10)) / / cycle 10 times at intervals of 3s. Build (); / / Scheduler associates triggers and starts scheduler.scheduleJob (job,trigger); scheduler.start ();} 1.3 Job and JobDetail

Job: a reflection-based task scheduling interface that all task classes implement and write their own business logic in the execute of the interface.

Job lifecycle: each time Job is executed, a new Job instance is created before the execute method. After the instance is called, the instance is released and then reclaimed by GC.

JobDetail: encapsulates Job, providing many properties to Job instances.

JobDetail attributes: name, group, jobClass, jobDataMap.

1.4 JobExecutionContext

Hereafter, JobExecutionContext is abbreviated as JEC.

JEC: when the scheduler calls Job, it passes JEC to the execute method of Job.

The role of JEC: Job obtains the running environment information and Job information through JEC.

1.5 JobDataMap

Hereafter, JobDataMap is abbreviated as JDM.

JDM: when a task is scheduled, the JDM is stored in JEC for easy access.

JDM advantages: implement the Map interface, you can access any serializable object, Job execution will pass parameters to JDM.

Obtain JDM parameter cases manually

HelloSchedulerDemo:

Package com.sugar.quartz.utils;import org.quartz.*;import org.quartz.impl.StdSchedulerFactory;/** * function description: timer configuration * * @ author XiaoNianXin * @ date 21:08 on 2021-12-13 * / public class HelloSchedulerDemo {public static void main (String [] args) throws SchedulerException {/ / 1, Scheduler-get scheduling instance from factory Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler () / / 2. Task instance-Task object JobDetail job = JobBuilder.newJob (HelloJob.class) .withIdentity ("job1", "group1") / / Task name, group name .usingJobData ("msg", "JDM uses-Detail") / / JDM passes parameters .build () / / 3, trigger-controls the number of execution times and execution time Trigger trigger = TriggerBuilder.newTrigger () .withIdentity ("trigger1", "group1") / / ditto .startNow () / / start .withschedule (SimpleScheduleBuilder.simpleSchedule ()) immediately. WithIntervalInSeconds (3). WithRepeatCount (10)) / / cycle 10 times at intervals of 3s .usingJobData ("msg", "JDM uses-Trigger") .build (); / / the scheduler associates triggers and starts scheduler.scheduleJob (job,trigger); scheduler.start ();}}

HelloJob:

Package com.sugar.quartz.utils;import org.quartz.Job;import org.quartz.JobDataMap;import org.quartz.JobExecutionContext;import org.quartz.JobExecutionException;import java.text.SimpleDateFormat;import java.util.Date / * feature description: timing service function * * @ author XiaoNianXin * @ date 20:52 on 2021-12-13 * / public class HelloJob implements Job {@ Override public void execute (JobExecutionContext context) throws JobExecutionException {/ / get the current time and format Date date = new Date (); SimpleDateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); String dateSrting = format.format (date) / / get JDM JobDataMap Detail_JDM = context.getJobDetail () .getJobDataMap (); JobDataMap Trigger_JDM = context.getTrigger () .getJobDataMap (); String detail_jdmString = Detail_JDM.getString ("msg"); String trigger_jdmString = Trigger_JDM.getString ("msg") System.out.println ("- -"); System.out.println ("detail_jdmString =" + detail_jdmString); System.out.println ("trigger_jdmString =" + trigger_jdmString) / / Business function simulates System.out.println ("start backup database, time:" + dateSrting); / / other content System.out.println ("Job run time:" + context.getJobRunTime ()); System.out.println ("Job current run time:" + context.getFireTime ()) System.out.println ("Job next run time:" + context.getNextFireTime ()); System.out.println ("- -");}} 2. The Job class implements the Setter method of the JDM parameter, and automatically binds the parameter when instantiated.

HelloJob:

/ / automatically bind the value private String msg;public void setMsg (String msg) {this.msg = msg;} / / corresponding to JDM key when instantiating to get JDMSystem.out.println (Trigger JDM: "+ msg)

Question: the key of JDM in JobDetail and Trigger above is "msg". Which one is this msg?

E.G: the value of JobDetail will be overwritten if you encounter key,Trigger with the same name, so msg is the value of Trigger JDM.

1.6 Job statu

Stateful Job: the same JDM is shared during multiple calls to Job.

Stateful Job: create a new JDM each time during multiple calls to Job.

Distinguishing cases with stateless Job

Expectation: stateless count output is always 1, stateful count output accumulates.

HelloSchedulerDemo:

/ / JobDeatil add a JDM to use as a counter .usingJobData ("count", 0)

Stateless HelloJob:

Package com.sugar.quartz.utils;import org.quartz.Job;import org.quartz.JobExecutionContext;import org.quartz.JobExecutionException;import java.text.SimpleDateFormat;import java.util.Date;/** * function description: task class * * @ author XiaoNianXin * @ date 20:52 on 2021-12-13 * / public class HelloJob implements Job {/ / automatically bind the value private String msg; private Integer count corresponding to JDM key when instantiation Public void setMsg (String msg) {this.msg = msg;} public void setCount (Integer count) {this.count = count;} @ Override public void execute (JobExecutionContext context) throws JobExecutionException {/ / get the current time and format Date date = new Date (); SimpleDateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); String dateSrting = format.format (date) / / get JDM System.out.println ("- -"); System.out.println ("Trigger JDM:" + msg); System.out.println ("Count:" + count) / / update count count++; context.getJobDetail () .getJobDataMap () .put ("count", count) of JobDetail JDM; / / Business function simulates System.out.println ("start backup database, time:" + dateSrting); / / other content System.out.println ("Job run time:" + context.getJobRunTime ()) System.out.println ("Job current run time:" + context.getFireTime ()); System.out.println ("Job next run time:" + context.getNextFireTime ()); System.out.println ("- -");}}

Stateful HelloJob:

/ / the task class, with the following comments, calls Job multiple times, and the data that persists Job,JDM will be saved for next time using @ PersistJobDataAfterExecution1.7 Trigger

Trigger commonly used: SimpleTrigger, CronTrigger.

The JobKey:Job instance is identified. When the trigger is triggered, the JobKey corresponding task is executed.

StartTime: the first trigger time.

EndTime: the trigger time is terminated.

A case of obtaining parameters by Trigger

HelloSchedulerTriggerDemo:

Package com.sugar.quartz.utils;import org.quartz.*;import org.quartz.impl.StdSchedulerFactory;import java.util.Date;/** * function description: timer configuration 2 * * @ author XiaoNianXin * @ date, 2021-12-13 21:08 * / public class HelloSchedulerTriggerDemo {public static void main (String [] args) throws SchedulerException {/ / task start time delayed by 3 s, end time delayed by 10 s Date startData = new Date () StartData.setTime (startData.getTime () + 3000); Date endData = new Date (); endData.setTime (endData.getTime () + 10000); / / 1, Scheduler-get scheduling instance from factory Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler () / / 2. Task instance-Task object JobDetail job = JobBuilder.newJob (helloJobTrigger.class) .withIdentity ("job1", "group1") / / Task name, group name .usingJobData ("msg", "JDM uses-Detail") / / JDM passes parameters .build () / / 3. Trigger-controls the number of execution times and execution time Trigger trigger = TriggerBuilder.newTrigger () .withidentity ("trigger1", "group1") / / Ibid. StartNow () / / start .startAt (startData) .endAt (endData) .build () immediately. / / Scheduler associates triggers and starts scheduler.scheduleJob (job,trigger); scheduler.start ();}}

HelloJobTrigger:

Package com.sugar.quartz.utils;import org.quartz.Job;import org.quartz.JobExecutionContext;import org.quartz.JobExecutionException;import org.quartz.PersistJobDataAfterExecution;import java.text.SimpleDateFormat;import java.util.Date / * function description: task class 2 * * @ author XiaoNianXin * @ date 20:52 on 2021-12-13 * / @ PersistJobDataAfterExecutionpublic class helloJobTrigger implements Job {@ Override public void execute (JobExecutionContext context) throws JobExecutionException {/ / get the current time and format Date date = new Date (); SimpleDateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); String dateSrting = format.format (date) / / Business function simulation System.out.println ("- -"); System.out.println ("start backup database, time:" + dateSrting) / / get JobKey,StartTime,EndTime System.out.println ("JobKey:" + context.getTrigger (). GetJobKey ()); System.out.println ("StartTime:" + format.format (context.getTrigger (). GetStartTime ()); System.out.println ("EndTime:" + format.format (context.getTrigger (). GetEndTime () System.out.println ("- -") }} / / run result-start backing up the database Time: 2021-12-13 23:25:06JobKey: group1.job1StartTime: 2021-12-13 23:25:06EndTime: 2021-12-13 22-13-13-25-13-13-13-13-13-13-12-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-13-12-13 SimpleTripper

Hereafter, SimpleTripper is abbreviated as ST.

ST: a specific time range starts / ends, and the Job design is repeated n times at a time interval.

ST attributes: start time, end time, number of repeats, and interval.

ST hint: if the end time is specified, then the end time priority > the number of repeats.

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