Hibernate延迟加载单列

Question

在Tomcat和Hibernate 5.0中使用Spring运行

尝试延迟加载单个列，这似乎在没有字节码增强的情况下不被支持。我尝试了执行these步骤，但是列仍然作为初始查询被加载。

@Bean( JpaConfig.EMF )
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
final DataSource dataSource,
final JpaVendorAdapter jpaVendorAdapter )
....
props.put( AvailableSettings.ENHANCER_ENABLE_LAZY_INITIALIZATION, Boolean.toString( true ) );
emf.setJpaPropertyMap( props );

列配置

@Column( name = "file_data", nullable = false )
@Basic( fetch = FetchType.LAZY )
    private byte[] fileData;

Spring配置类

@Configuration
@EnableLoadTimeWeaving

启动输出

[INFO ] [17:22:56] [localhost-startStop-1] weaving.DefaultContextLoadTimeWeaver:76 - Determined server-specific load-time weaver: org.springframework.instrument.classloading.tomcat.TomcatLoadTimeWeaver
Jun 12, 2018 5:22:56 PM org.apache.catalina.loader.WebappClassLoaderBase addTransformer
INFO: Added class file transformer [org.springframework.context.weaving.AspectJWeavingEnabler$AspectJClassBypassingClassFileTransformer@6086a542] to web application [ROOT].
[INFO ] [17:22:56] [localhost-startStop-1] weaving.DefaultContextLoadTimeWeaver:76 - Determined server-specific load-time weaver: org.springframework.instrument.classloading.tomcat.TomcatLoadTimeWeaver
[INFO ] [17:27:05] [localhost-startStop-1] jpa.LocalContainerEntityManagerFactoryBean:356 - Building JPA container EntityManagerFactory for persistence unit 'persistenceUnit'
Jun 12, 2018 5:27:20 PM org.apache.catalina.loader.WebappClassLoaderBase addTransformer
INFO: Added class file transformer [Standard ClassFileTransformer wrapping JPA transformer: org.hibernate.jpa.internal.enhance.EnhancingClassTransformerImpl@20635e8] to web application [ROOT].

我是不是遗漏了什么？

Answer 1

根据JPA规范，延迟加载指令只是对持久化提供者Hibernate的一个提示。提供商可能不会尊重您的提示。总的来说，你的目标是什么？在获取基本类型的附加字段时，您不会有太多松散，因为没有涉及到对象图。如果您有大型数组，请添加@Lob注释。