如何有条件地启用或禁用 Spring 中的预定作业? [英] How to conditionally enable or disable scheduled jobs in Spring?

问题描述

我使用 @Scheduled 注释在 Spring 中使用 cron 样式模式定义计划作业.

I am defining scheduled jobs with cron style patterns in Spring, using the @Scheduled annotation.

cron 模式存储在配置属性文件中.实际上有两个属性文件:一个是默认配置，另一个是依赖于环境(例如 dev、test、prod customer 1、prod customer 2 等)并覆盖一些默认值的配置文件配置.

The cron pattern is stored in a config properties file. Actually there are two properties files: one default config, and one profile config that is environment dependent (e.g. dev, test, prod customer 1, prod customer 2 etc.) and overrides some of the default values.

我在 spring 上下文中配置了一个属性占位符 bean，它允许我使用 ${} 样式占位符从我的属性文件中导入值.

I configured a property placeholder bean in my spring context which allows me to use ${} style placeholders to import values from my properties files.

作业 bean 如下所示:

The job beans looks like this:

@Component
public class ImagesPurgeJob implements Job {

    private Logger logger = Logger.getLogger(this.getClass());

    @Override
    @Transactional(readOnly=true)
    @Scheduled(cron = "${jobs.mediafiles.imagesPurgeJob.schedule}")
    public void execute() {
        //Do something
            //can use DAO or other autowired beans here
    }
}

我的上下文 XML 的相关部分:

Relevant parts of my context XML :

<!-- Enable configuration of scheduled tasks via annotations -->
    <task:annotation-driven/>

<!-- Load configuration files and allow '${}' style placeholders -->
    <bean class="org.springframework.context.support.PropertySourcesPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:config/default-config.properties</value>
                <value>classpath:config/environment-config.properties</value>
            </list>
        </property>
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="false"/>
    </bean>

我真的很喜欢这个.使用最少的 XML 非常简单和干净.

I really like this. It's quite simple and clean with minimal XML.

但是我还有一个要求:在某些情况下，其中一些工作可以完全禁用.

However I have one more requirement: some of these jobs can be totally disabled in some cases.

因此，在我使用 Spring 管理它们之前，我手动创建了它们，并且在配置文件中有一个布尔参数和 cron 参数，用于指定是否必须启用作业:

So, before I used Spring to manage them I created them manually and there is a boolean parameter along with the cron parameter in the config files, to specify if the job has to be enabled or not:

jobs.mediafiles.imagesPurgeJob.enable=true or false
jobs.mediafiles.imagesPurgeJob.schedule=0 0 0/12 * * ?

如何在 Spring 中使用此参数根据此配置参数有条件地创建或直接忽略 bean?

How can I use this parameter in Spring to conditionally create or just plainly ignore the bean, depending on this config parameter?

一个明显的解决方法是定义一个永远不会评估的 cron 模式，因此永远不会执行作业.但是还是会创建bean，配置会有点晦涩，所以我觉得一定有更好的解决方案.

One obvious workaround would be to define a cron pattern that would never evaluate, so the job is never executed. But the bean would still be created and the config would be a bit obscure, so I feel there must be a better solution.

推荐答案

@Component
public class ImagesPurgeJob implements Job {

    private Logger logger = Logger.getLogger(this.getClass());

    @Value("${jobs.mediafiles.imagesPurgeJob.enable}")
    private boolean imagesPurgeJobEnable;

    @Override
    @Transactional(readOnly=true)
    @Scheduled(cron = "${jobs.mediafiles.imagesPurgeJob.schedule}")
    public void execute() {

         //Do something
        //can use DAO or other autowired beans here
        if(imagesPurgeJobEnable){

            Do your conditional job here...

        }
    }
}

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