java - @Scheduled方法无法使用存储库

Question

我添加了一个方法 @Scheduled(fixedDelay = 0)注释，并且在方法中我使用一些存储库，在类中初始化为: @Autowired private ContactRepository contactRepository;

关于存储库:public interface ContactRepository extends CrudRepository<Contact, String>

问题是我遇到了异常:

java.lang.IllegalArgumentException: null
    at java.util.concurrent.ScheduledThreadPoolExecutor.scheduleWithFixedDelay(ScheduledThreadPoolExecutor.java:589) ~[na:1.8.0_151]
    at java.util.concurrent.Executors$DelegatedScheduledExecutorService.scheduleWithFixedDelay(Executors.java:738) ~[na:1.8.0_151]
    at org.springframework.scheduling.concurrent.ConcurrentTaskScheduler.scheduleWithFixedDelay(ConcurrentTaskScheduler.java:235) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleFixedDelayTask(ScheduledTaskRegistrar.java:511) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleFixedDelayTask(ScheduledTaskRegistrar.java:485) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleTasks(ScheduledTaskRegistrar.java:362) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.config.ScheduledTaskRegistrar.afterPropertiesSet(ScheduledTaskRegistrar.java:332) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:280) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:211) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:102) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:400) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:354) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:888) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:161) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
    at com.user.app.Main.main(Main.java:17) [classes/:na]

更新:

当我使用fixedDelay = 1(或更多)时，它可以工作。为什么？

Answer 1

根据Javadoc for ScheduledExecutorService.scheduleWithFixedDelay(Runnable, long, long, TimeUnit) , IllegalArgumentException发生在 period <= 0 时。所以大概@Scheduled(fixedDelay = 0)原因period成为0导致出现此异常。

也许是Scheduled方法不是你真正想要的？如果您想在启动后执行一个方法，也许这个问题会有所帮助:Execute method on startup in spring