How to use Quartz to implement Java high-availability scheduled tasks?

Scheduled Task Usage Guide

If you want to do scheduled tasks, have high availability requirements, or just want to get started quickly and get started easily, then choose It's exactly right.

The scheduled task module further encapsulates the Quartz framework and makes it simpler to use.

1. Introduce dependencies

<dependency>
    <groupId>xin.altitude.cms</groupId>
    <artifactId>ucode-cms-quartz</artifactId>
    <version>1.5.4.1</version>
</dependency>

2. Get started quickly

Implement the org.quartz.Job interface; use annotationsCronExp Add the scheduling strategy of the task; use the annotation Component to inject the task into the container.

Start the project, and the scheduled tasks will be monitored and run.

@Component
@DisallowConcurrentExecution
@CronExp(cron = "0/5 * * * * ?")
public class DemoJob implements Job {
    @Override
    public void execute(JobExecutionContext context) {
        System.out.println("任务1：" + LocalDateTime.now());
    }
}

3. Manually trigger scheduled tasks

In addition to running periodically at the existing frequency, scheduled tasks also have the ability to be triggered manually through the interface.

Call the following interface to manually trigger the task with the task ID number jobId.

http://localhost:8080/cms-api/quartz/job/{jobId}

If there is a need to manually trigger a scheduled task, the task ID is required Unique and and known, so it needs to be specified manually when writing a scheduled task.

@CronExp(id = 1, cron = "0/5 * * * * ?")

The task ID can be specified by annotating the id attribute of CronExp. If the task ID is not explicitly specified, a random ID will be used. The known conditions are not met, so it cannot be triggered manually.

4. Tasks with parameters

Although most tasks do not require the injection of parameters, there are still a small number of scenarios that require the injection of parameters into scheduled tasks.

public void execute(JobExecutionContext context) {
    /* 如果在调用任务时传入了参数，则能够从Map中获取 */
    Map<String, Object> dataMap = context.getMergedJobDataMap();
    /* 比如从Map中获取一个键值对，一般来说参数均为基本数据类型 */
    Object key = dataMap.get("key");
    System.out.println("任务2：" + LocalDateTime.now() + ": " + key);
}

When writing a scheduled task, you can parse a Map from the JobExecutionContext object to complete the injection of parameters.

http://localhost:8080/cms-api/quartz/job/1?key=a

The meaning of the above http call is to manually trigger the task with the task ID [1], and pass it the parameter [key] with the value [a].

5. Task concurrency

This framework does not support task concurrency. In other words, concurrency is not good for scheduled tasks, so it needs to be disabled manually.

It should be noted that the concurrency of Quartz refers to whether the new task will be executed when the task execution time exceeds the task scheduling cycle and the previous task has not been executed.

Generally speaking, it is necessary to display the prohibition of concurrency. Add the annotation DisallowConcurrentExecution to the task class to disable task concurrency.

6. Persistence

If the scheduled task has high availability requirements, the task needs to be persisted. After the scheduled task data is persisted into the database, multiple applications can be opened. After persistent multi-node deployment of scheduled tasks, a single node failure in the cluster will not affect the execution of scheduled tasks.

Timed task persistence, you only need to modify the yml file configuration to achieve the goal, without modifying the code. Generally speaking, Mysql is used as a persistent container.

spring:
  quartz:
    properties:
      org.quartz.jobStore.isClustered: true
      org.quartz.jobStore.class: org.quartz.impl.jdbcjobstore.JobStoreTX
      org.quartz.jobStore.driverDelegateClass: org.quartz.impl.jdbcjobstore.StdJDBCDelegate
      org.quartz.jobStore.dataSource: qzDS
      org.quartz.dataSource.qzDS.driver: com.mysql.cj.jdbc.Driver
      org.quartz.dataSource.qzDS.URL: jdbc:mysql://localhost:3306/quartz-demo
      org.quartz.dataSource.qzDS.user: root
      org.quartz.dataSource.qzDS.password: 123456

Except for modifying the five parameters of host, port, database name, user name, and password, the other parameters can use the default values.

After configuring the database connection, use the SQL script and pay attention to initializing the database

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