無法實例化bean構造函數拋出異常;嵌套的例外是顯示java.lang.NullPointerException

Question

我的基於Java的配置是

@Configuration 
@ComponentScan(basePackages = { "com.doly.jproject" }) 
@EnableTransactionManagement 
@EnableJpaRepositories (basePackages = "com.doly.jproject.repository") 
public class RootConfigurer extends WebMvcConfigurerAdapter { 

    private Properties jpaProperties; 

    @Bean 
    public DriverManagerDataSource dataSource() { 
     DriverManagerDataSource dataSource = new DriverManagerDataSource(); 
     dataSource.setDriverClassName("com.mysql.jdbc.Driver"); 
     dataSource.setUrl("jdbc:mysql://localhost/dbga"); 
     dataSource.setUsername("root"); 
     dataSource.setPassword(""); 
     return dataSource; 
    } 

    @Bean 
    public EntityManagerFactory entityManagerFactory() throws SQLException { 

     LocalContainerEntityManagerFactoryBean entityManagerFactory = 
       new LocalContainerEntityManagerFactoryBean(); 
     entityManagerFactory.setPackagesToScan("com.doly.jproject.entity"); 
     entityManagerFactory.setDataSource(dataSource()); 

     jpaProperties = new Properties();  
     jpaProperties.put("hibernate.show_sql", true); 
     jpaProperties.put("hibernate.hbm2ddl.auto", "create"); 

     entityManagerFactory.setJpaProperties(jpaProperties); 
     entityManagerFactory.setPersistenceProvider(new HibernatePersistenceProvider()); 

     return entityManagerFactory.getObject(); 
    } 


    @Bean 
    @Qualifier(value = "entityManager") 
    public EntityManager entityManager(EntityManagerFactory entityManagerFactory) { 
     return entityManagerFactory.createEntityManager(); 
    } 

    @Bean 
    public JpaTransactionManager transactionManager() { 
     JpaTransactionManager transactionManager = new JpaTransactionManager(); 
     transactionManager.setDataSource(dataSource()); 
     return transactionManager; 
    } 
} 

但是當我想在我的@服務類從javax.persistence.EntityManager初始化的org.hibernate.Session對象

@Autowired 
@Qualifier(value = "entityManager") 
private EntityManager entityManager;  
private Session session = entityManager.unwrap(org.hibernate.Session.class); 

我得到錯誤+堆棧跟蹤爲

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener 
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'homeController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.service.VidService com.doly.jproject.controllers.HomeController.vidService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService' defined in file [F:\Spring Workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\jobsnetwork\WEB-INF\classes\com\doly\jproject\service\VidService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.doly.jproject.service.VidService]: Constructor threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480) 
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) 
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) 
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) 
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5014) 
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5528) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565) 
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at java.lang.Thread.run(Thread.java:745) 
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.service.VidService com.doly.jproject.controllers.HomeController.vidService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService' defined in file [F:\Spring Workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\jobsnetwork\WEB-INF\classes\com\doly\jproject\service\VidService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.doly.jproject.service.VidService]: Constructor threw exception; nested exception is java.lang.NullPointerException 
    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) 
    ... 22 more 
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.service.VidService com.doly.jproject.controllers.HomeController.vidService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService' defined in file [F:\Spring Workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\jobsnetwork\WEB-INF\classes\com\doly\jproject\service\VidService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.doly.jproject.service.VidService]: Constructor threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1101) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1120) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1044) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942) 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533) 
    ... 24 more 
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.doly.jproject.service.JobService]: Constructor threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:163) 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1094) 
    ... 35 more 
Caused by: java.lang.NullPointerException 
    at com.doly.jproject.service.VidService.<init>(VidService.java:42) 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) 
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422) 
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147) 
    ... 37 more 

和com.doly.jproject.service.VidService.<init>(VidService.java:42)是

和

public void updateJobCategory(Video video) { 
     Video video = (Video)session.get(Video.class, id);// Here it causes com.doly.jproject.service.VidService.<init>(VidService.java:42) 
video.getCustomers().clear();//removes all the existing customers 
Customer customer1 = new Customer(); 
customer1.getVideos().add(video)//adding video to the customer 
video.getCustomers().add(customer1); 
session.update(video) 


    } 

UPDATE 當我改變

@Autowired 
    @Qualifier(value = "entityManager") 
    private EntityManager entityManager;  
    private Session session; 

和更新方法我寫

public void updateJobCategory(Video video) { 
    session= entityManager.unwrap(org.hibernate.Session.class); 
    Video video = (Video)session.get(Video.class, id); 
    video.getCustomers().clear();//removes all the existing customers 
    Customer customer1 = new Customer(); 
    customer1.getVideos().add(video)//adding video to the customer 
    video.getCustomers().add(customer1); 
    session.update(video) 


     } 

我得到

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener 
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'homeController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.service.VidService com.doly.jproject.controllers.HomeController.vidService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.repository.VidRepository com.doly.jproject.VidService.vidRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidRepository': Cannot create inner bean '(inner bean)#681afbff' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480) 
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) 
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) 
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) 
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5014) 
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5528) 
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575) 
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565) 
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at java.lang.Thread.run(Thread.java:745) 
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.service.VidService com.doly.jproject.controllers.HomeController.vidService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.repository.VidRepository com.doly.jproject.service.VidService.vidRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidRepository': Cannot create inner bean '(inner bean)#681afbff' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    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) 
    ... 22 more 
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.rhcloud.jobsnetwork.repository.JobRepository com.doly.jproject.service.VidService.vidRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidRepository': Cannot create inner bean '(inner bean)#681afbff' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1120) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1044) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942) 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533) 
    ... 24 more 
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.doly.jproject.repository.VidRepository com.doly.jproject.service.VidService.vidRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidRepository': Cannot create inner bean '(inner bean)#681afbff' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    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) 
    ... 35 more 
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'vidRepository': Cannot create inner bean '(inner bean)#681afbff' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:313) 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:129) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1477) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1222) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1120) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1044) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942) 
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533) 
    ... 37 more 
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#681afbff': Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1119) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1014) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) 
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:299) 
    ... 50 more 
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.persistence.EntityManager]: Factory method 'createSharedEntityManager' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) 
    ... 55 more 
Caused by: java.lang.NullPointerException 
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.initProxyClassLoader(SharedEntityManagerCreator.java:198) 
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.<init>(SharedEntityManagerCreator.java:190) 
    at org.springframework.orm.jpa.SharedEntityManagerCreator.createSharedEntityManager(SharedEntityManagerCreator.java:162) 
    at org.springframework.orm.jpa.SharedEntityManagerCreator.createSharedEntityManager(SharedEntityManagerCreator.java:119) 
    at org.springframework.orm.jpa.SharedEntityManagerCreator.createSharedEntityManager(SharedEntityManagerCreator.java:91) 
    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.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) 
    ... 56 more 

在我的@Service類中，如何從javax.persistence.EntityManager獲得org.hibernate.Session的一個？請幫忙！

Answer 1

這似乎是有問題的對我說：

@Autowired 
@Qualifier(value = "entityManager") 
private EntityManager entityManager;  
private Session session = entityManager.unwrap(org.hibernate.Session.class); 

自動裝配構造你的對象後，會發生。這意味着當你的服務被創建時，它將在entityManager被設置之前嘗試調用entityManager.unwrap。

另外，保存這樣的會話通常不是一種好的做法。您應該爲每個執行的操作/事務創建一個新的EntityManager/Session。您配置事物的方式在應用程序的整個生命週期中只會有一個EntityManager bean，這會導致問題。你可能想什麼：

@Autowired 
private EntityManagerFactory entityManagerFactory; 

然後

public void doStuff() { 
    EntityManager entityManager = entityManagerFactory.createEntityManager(); 
} 

既然你已經使用Spring，你可能要考慮@Transactional註釋也。