在 Spring Boot 应用程序中安排任务的最佳方法是什么

Question

I am current developing an application based on Spring-Boot.

I know that annotation like @Scheduled can schedule tasks. Since users in my application wanna send mails at different time and send only once.

I have already read the post Spring scheduling task - run only once , but it is weird always "new" an localExecutor in a Spring based application.

In that way , once a user schedule sending an email, I have to "new" an localExecutor for his task.

So , are there any better ways?

Answer 1

The simplest way to schedule tasks in Spring is to create method annotated by @Scheduled in spring managed bean. It also required @EnableScheduling in any @Configuration classes.

Spring tutorial

Answer 2

You can use crontab inside @Scheduled

 private AtomicInteger counter = new AtomicInteger(0);

@Scheduled(cron = "*/2 * * * * *")
public void cronJob() {
    int jobId = counter.incrementAndGet();
    System.out.println("Job " + new Date() + ", jobId: " + jobId);
}

Answer 3

you should use quartz-scheduler and send mails at different time and send only once. - put this as a business logic in your code. Please see for spring boot -quartz integration https://github.com/davidkiss/spring-boot-quartz-demo

Answer 4

You can use Quartz Scheduler .

Quartz is a richly featured, open source job scheduling library that can be integrated within virtually any Java application - from the smallest stand-alone application to the largest e-commerce system. Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs; jobs whose tasks are defined as standard Java components that may execute virtually anything you may program them to do. The Quartz Scheduler includes many enterprise-class features, such as support for JTA transactions and clustering.

You may find some blogs, illustrating how to use quartz in spring boot including defining beans of JobDetail, Trigger, factories... etc which is little overwhelming and cumbersome.

There is simple way to do the same.

You may give a try to https://github.com/mejariamol/quartz-easy . This library simplifies the quartz scheduler integration in spring boot framework. I came up with this while setting up quartz scheduler in one of the projects at work.

1. Annotate your Job implementation with Scheduled annotation with required configuration by setting suitable fields present in the annotation.

import com.indusnode.quartz.annotation.Scheduled;
...
@Scheduled(interval="5", intervalType=Scheduled.IntervalType.SEC)
class TestJob implements Job {
    //...
}

2. Set application property qe.base-package as your base package name of the project which will contain all your job implementations. Also, add com.indusnode as a value to basePackage in component scan.
3. And you are done! No need to define factories, JobDetail, Triggers...etc.

To use this library, include the quartz-easy artifact in the dependencies section of your pom.xml

<dependency>
  <groupId>com.indusnode</groupId>
  <artifactId>quartz-easy</artifactId>
  <version>1.0.0</version>
</dependency>

For details, please refer https://search.maven.org/artifact/com.indusnode/quartz-easy/1.0.0/jar

Answer 5

Spring @Scheduled annotation will execute multiple times if you have more than one instance of your app where you have @Scheduled annotation.

If you are using PCF, you can use PCF scheduler https://docs.pivotal.io/scheduler/1-2/using-jobs.html to avoid this issue. Using Tasks can solve this issue.