从Spring Boot 1.5迁移到2.0时获得BeanInstantiationException

Question

今天，我想从Spring Boot 1.5.0升级到2.0.6，但是在运行时Spring无法实例化。

BeanConfig类：

@Configuration
public class BeanConfig {

    @Autowired
    private EntityManagerFactory entityManagerFactory;

    @Bean
    public SessionFactory getSessionFactory() {
        if (entityManagerFactory.unwrap(SessionFactory.class) == null) {
            throw new NullPointerException("factory is not a hibernate factory");
        }
        return entityManagerFactory.unwrap(SessionFactory.class);
    }
}

StackTrace：

    org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'beanConfig': Unsatisfied dependency expressed through field 'entityManagerFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'getSessionFactory' defined in class path resource [com/devglan/BeanConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Circular reference involving containing bean 'beanConfig' - consider declaring the factory method as static for independence from its containing instance. Factory method 'getSessionFactory' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:370) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1336) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:572) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:548) ~[spring-context-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1242) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1230) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
    at com.devglan.Application.main(Application.java:10) ~[classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'getSessionFactory' defined in class path resource [com/devglan/BeanConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Circular reference involving containing bean 'beanConfig' - consider declaring the factory method as static for independence from its containing instance. Factory method 'getSessionFactory' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:591) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1246) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:581) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    ... 19 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Circular reference involving containing bean 'beanConfig' - consider declaring the factory method as static for independence from its containing instance. Factory method 'getSessionFactory' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:583) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    ... 31 common frames omitted
Caused by: java.lang.NullPointerException: null
    at com.devglan.BeanConfig.getSessionFactory(BeanConfig.java:19) ~[classes/:na]
    at com.devglan.BeanConfig$$EnhancerBySpringCGLIB$$e2592dce.CGLIB$getSessionFactory$0(<generated>) ~[classes/:na]
    at com.devglan.BeanConfig$$EnhancerBySpringCGLIB$$e2592dce$$FastClassBySpringCGLIB$$8a79c2f8.invoke(<generated>) ~[classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) ~[spring-core-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:365) ~[spring-context-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    at com.devglan.BeanConfig$$EnhancerBySpringCGLIB$$e2592dce.getSessionFactory(<generated>) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
    ... 32 common frames omitted

哪里错了？

Answer 1

使用 tx.begin(); EntityA a = new EntityA(); EntityB b1 = new EntityB(); EntityB b2 = new EntityB(); b1.setA(a); b2.setA(a); em.persist(a); em.persist(b1); em.persist(b2); tx.commit(); em.clear(); // projection with join fetch doesn't work. // em.createQuery("select new dto.WrapperDto( a, bs ) from EntityA a left outer join fetch a.bs bs where a.id = 1", WrapperDto.class).getResultList(); // a possible solution EntityA aFound = em.find(EntityA.class, 1L); List<EntityB> bs = em.createQuery("select b from EntityB b where b.a = :a", EntityB.class).setParameter("a", aFound).getResultList(); WrapperDto dto = new WrapperDto(aFound, bs); 代替@PersistenceUnit的{​​{1}}

Answer 2

我得到了答案。不需要额外的BeanConfig类。在启动应用程序上使用@EnableAutoConfiguration。请为您的DaoImpl参考以下代码。

@Repository
@Transactional
public class UserDaoImpl implements UserDao {

    @Autowired
    private EntityManagerFactory entityManagerFactory;

    public List<UserDetails> getUserDetails() {
        Session session = entityManagerFactory.unwrap(SessionFactory.class).openSession();      
        Query query = session.createQuery("from UserDetails");      
        return query.getResultList();
    }
}

Answer 3

只需将@Autowired更改为@PersistenceContext，它对我有用。

@PersistenceContext
private EntityManagerFactory entityManagerFactory;