使用Spring创建Scheduler Bean时发生NullPointerException

我想用Spring来创建一个调度器。 

@Configuration @EnableScheduling public class MyScheduler { @Autowired MyBusinessService businessService; @Scheduled(cron = "* * * * * *") public void myCronMethod() { } }

在应用程序启动过程中，出现以下错误： 

 java.lang.NullPointerException at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.resolveSchedulerBean(ScheduledAnnotationBeanPostProcessor.java:281) at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:221) at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:200) at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:94) at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167) at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:383) at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:337) at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:882) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5068) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5584) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1572) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1562) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)

在ScheduledAnnotationBeanPostProcessor中 ，持有者为null： 

 NamedBeanHolder<T> holder = ((AutowireCapableBeanFactory) this.beanFactory).resolveNamedBean(schedulerType);

schedulerType是： 

 interface org.springframework.scheduling.TaskScheduler

该应用程序是一个JSF应用程序。 即时通讯使用Java 8和春天版本4.3.6，但是与Ant和没有依赖管理，所以缺少库或库不匹配是一种可能性。

在Kotlin应用程序中刚刚出现同样的错误，我的解决方法是手动将TaskScheduler添加到我的应用程序配置中：

Java的例子是从这里拿走的。 

 @Bean public ThreadPoolTaskScheduler threadPoolTaskScheduler(){ ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler(); threadPoolTaskScheduler.setPoolSize(5); threadPoolTaskScheduler.setThreadNamePrefix( "ThreadPoolTaskScheduler"); return threadPoolTaskScheduler; }

我的Kotlin版本是 

 @Bean fun threadPoolTaskScheduler() = ThreadPoolTaskScheduler().apply { setPoolSize(5) setThreadNamePrefix("ThreadPoolTaskScheduler") }

（我还没有尝试过，但我相信升级到Spring 5也将解决这个问题 – 这个提交会抛出一个异常，其中的空指针将被生成。）

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