Java Spring-使用@PostConstruct时获取NullPointException

我正在使用一个

@PostCostruct

注释来获取一个初始化方法，以便在Sprin引导应用程序启动时运行代码

@Service("jobManager")
public class JobManager {

    @Autowired
    SchedulerFactoryBean scheduler;

    @Autowired
    InterruttoreService interruttoreService;

    @PostConstruct
    public void createInitialJobs() throws SchedulerException {
        List<Interruttore> interruttori = interruttoreService.findAllSwitches();

        for (int i = 0; i < interruttori.size(); i++) {
            Interruttore interruttore = interruttori.get(i);
            interruttoreService.toggleSwitchOnStartup(interruttore); 

        }

    }

从这个方法调用jobManager时，我得到了一个NullPointerException，我不知道为什么bean是在@PostConstruct期间创建的

这是错误的堆栈跟踪

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'interruttoreService': Unsatisfied dependency expressed through field 'jobManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jobManager': Invocation of init method failed; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:569)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:349)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1219)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1128)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1056)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:566)
    ... 53 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jobManager': Invocation of init method failed; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:408)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1575)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1128)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1056)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:566)
    ... 66 more
Caused by: java.lang.NullPointerException
    at it.besmart.service.InterruttoreServiceImpl.toggleSwitchOnStartup(InterruttoreServiceImpl.java:112)
    at it.besmart.service.InterruttoreServiceImpl$$FastClassBySpringCGLIB$$907e162e.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655)
    at it.besmart.service.InterruttoreServiceImpl$$EnhancerBySpringCGLIB$$e2a6ab4b.toggleSwitchOnStartup(<generated>)
    at it.besmart.quartz.JobManager.createInitialJobs(JobManager.java:47)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:365)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:310)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:133)
    ... 78 more

---

这是紧密耦合的代码（您将

InterruttoreService

注入

JobManager

，同时

JobManager

注入

InterruttoreService

）

---

为什么不从

JobManager

中删除

InterruttoreService

注入，并让

切换开关启动（）

在

@PostCostruct

带注释的方法中完成所有

InterruttorService

中直接连接

作业管理器的位置。
问题是您的服务名称有一个小的输入错误

你有你的服务

@Service("jobManager")//first j lowercase
public class JobManager {


@Autowired //In your Autowired if you dont say a qualifier name will try to find names as "JobManager" first J uppercase
JobManager jobManager;

解决方案：

删除服务中的名称，仅保留

@Service
public class JobManager {


添加限定符

@Autowired
@Qualifier("jobManager")
JobManager jobManager;


注释掉@PostConstruct并检查InterruttorService是否在启动后自动连接正确。我怀疑bean的定义是错误的，这可能导致注入没有发生。检查是否有InterruttorService的bean。如果是这样，请检查是否有一个名为“JobManager”的bean用于JobManager。是否可以发布异常？以及自动连接jobManager的代码部分？能否将代码粘贴到自动连接jobManager服务的位置？谢谢，我试图回答您的问题comments@besmart你忘了在自动连接jobManager的地方添加代码：）我正在尝试，但是现在我遇到了一个异常，Hibernate无法获得调用
findAllSwitches的会话
@Service
public class JobManager {

@Autowired
@Qualifier("jobManager")
JobManager jobManager;