java - 延迟加载和 Hibernate.initialize() 的问题；

标签 java spring hibernate

我有一个Order包含延迟加载属性的类 List<OrderItem> 。我需要让它保持延迟加载。 在一种情况下，我通过 Spring JPARepository 加载所有订单:

@org.springframework.transaction.annotation.Transactional;
protected void doThingsWithOrderItems() {
    List<Order> orders = orderRepository.findAll();
    for (Order order : orders) {
        Hibernate.initialize(orders.getOrderItems());
        // do things with orders and their order items
    }
}

前面的方法是在 @PostConstruct 中调用的方法@Configuration类

我的问题是我得到:

ERROR 15580 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:137) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) ~[spring-context-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at com.lh.application.MyApplication.main(MyApplication.java:10) [classes/:na]
Caused by: org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat
    at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.initialize(TomcatEmbeddedServletContainer.java:123) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.<init>(TomcatEmbeddedServletContainer.java:84) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getTomcatEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:554) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:179) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:164) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    ... 8 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'initSettingsConfigurator': Invocation of init method failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.lh.application.entity.Order.OrderItems, could not initialize proxy - no Session
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:137) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:409) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1620) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:372) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:234) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:215) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addServletContextInitializerBeans(ServletContextInitializerBeans.java:91) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.<init>(ServletContextInitializerBeans.java:79) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getServletContextInitializerBeans(EmbeddedWebApplicationContext.java:241) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.selfInitialize(EmbeddedWebApplicationContext.java:228) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.access$000(EmbeddedWebApplicationContext.java:89) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext$1.onStartup(EmbeddedWebApplicationContext.java:213) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.springframework.boot.context.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:55) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5196) ~[tomcat-embed-core-8.5.20.jar:8.5.20]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[tomcat-embed-core-8.5.20.jar:8.5.20]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419) ~[tomcat-embed-core-8.5.20.jar:8.5.20]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409) ~[tomcat-embed-core-8.5.20.jar:8.5.20]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_91]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) ~[na:1.8.0_91]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) ~[na:1.8.0_91]
    at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_91]
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.lh.application.entity.Order.orderItems, could not initialize proxy - no Session
    at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:587) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:204) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:566) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:135) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.collection.internal.PersistentSet.iterator(PersistentSet.java:163) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at com.lh.application.entity.Order.doThingsWithOrderItem(Order.java:206) ~[classes/:na]
    at com.lh.application.config.InitSettingsConfigurator.doThingsWithOrderItems(InitSettingsConfigurator.java:169) ~[classes/:na]
    at com.lh.application.config.InitSettingsConfigurator.init(InitSettingsConfigurator.java:159) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_91]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_91]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_91]
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:311) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:134) ~[spring-beans-4.3.11.RELEASE.jar:4.3.11.RELEASE]
    ... 34 common frames omitted

我使用 @Transactional 方法，根据之前的相关问题和答案，我希望我的解决方案能够发挥作用。怎么了？

最佳答案

您很可能通过 this 引用调用 doThingsWithOrderItems，这基本上是对非代理对象上的方法的调用。为了让 Spring 创建代理，您应该使用所谓的 self-injection图案:

@Component
public class YourBean {

    @Autowire
    private YourBean yourBean;
    
    @PostConstruct
    private init(){
        yourBean.doThingsWithOrderItems();
    }

    @org.springframework.transaction.annotation.Transactional;
    public void doThingsWithOrderItems() {
        List<Order> orders = orderRepository.findAll();
        for (Order order : orders) {
            Hibernate.initialize(orders.getOrderItems());
            // do things with orders and their order items
        }
    }
}

请注意，Spring Framework 中的自注入(inject)在 4.3 版本之前可能无法工作。

解决此问题的另一种(可能是更好的)方法是将事务方法提取到单独的 bean 中。在大多数情况下，它会给你一个更清晰的代码，更容易测试(因为模拟依赖关系总是比在 Mockito 中通过 @Spy 进行部分模拟更容易、更好)。

关于java - 延迟加载和 Hibernate.initialize() 的问题；，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47120565/

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