如何在spring-boot中启用TaskScheduler？

Question

我正在使用spring-boot设置弹簧默认值.我想使用这种@EnableScheduling机制,并有条件地安排我的任务.

因此我必须实现SchedulingConfigurer并设置TaskScheduler明确.

但是当注入时TaskScheduler,我得到以下错误.但是为什么spring-boot不会相应地自动提供调度程序呢？

@Configuration
@EnableAutoConfiguration
@EnableScheduling
public class AppConfig {

}

@Service
public class JobService implements SchedulingConfigurer {
    @Autowired
    private TaskScheduler taskScheduler;

    //schedule the task dynamically
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(taskScheduler); //fails
        taskRegistrar.addTriggerTask(task, trigger);
    }
}

错误:

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.scheduling.TaskScheduler; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.scheduling.TaskScheduler] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
    ... 15 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.scheduling.TaskScheduler] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1308)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1054)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:949)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533)
    ... 17 more

Answer 1

您不需要在上面设置调度程序ScheduledTaskRegistrar.如果尚未配置,则默认为ConcurrentTaskScheduler包装单线程计划执行程序:

if (this.taskScheduler == null) {
    this.localExecutor = Executors.newSingleThreadScheduledExecutor();
    this.taskScheduler = new ConcurrentTaskScheduler(this.localExecutor);
}

如果您对此默认计划程序感到满意,则可以删除自动装配TaskScheduler和调用以将其设置为ScheduledTaskRegistrar.另外,正如Marten在评论中所建议的那样,你应该建立SchedulingConfigurer一个配置类而不是服务.

这些更改使您的代码看起来像这样:

@Configuration
static class TaskConfiguration implements SchedulingConfigurer {

    //schedule the task dynamically
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.addTriggerTask(task, trigger);
    }
}