java - LazyInitializationException 与 @Any(fetch = FetchType.EAGER) 和 Spring-boot

Question

尽管有“fetch = FetchType.EAGER”，但我遇到了常见异常“org.hibernate.LazyInitializationException:无法初始化代理 - 无 session ”，我可以't(不想)手动管理hibernate session (我使用Spring-Boot-starter-data-jpa)。

我有一个 Hilder 实体，其中包含 CommonType(TapeA 或 TypeB)的属性:

  @Entity
public class Holder<T extends CommonType> {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;

@Any(metaColumn = @Column(name = "type", nullable = false), optional = false, fetch = FetchType.EAGER)
@Cascade(org.hibernate.annotations.CascadeType.ALL )
@AnyMetaDef(
        idType = "long",
        metaType = "string",
        metaValues = {
                @MetaValue(value = "TypeA", targetEntity = TypeB.class),
                @MetaValue(value = "TypeB", targetEntity = TypeA.class)
        })
@JoinColumn(name = "property_id", nullable = false)
private T type; 
 //getters and setters}

B 型看起来像 A 型:

@Entity
public class TypeA implements CommonType {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    private double param=0;
//getters and setters
}

以及 Holder 的存储库:

import org.springframework.transaction.annotation.Transactional;

@Transactional
public interface HolderRepository extends CrudRepository<Holder, Long> {
}

运行者:

@Configuration
@EnableAutoConfiguration
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context =       SpringApplication.run(Application.class);
    HolderRepository repository = context.getBean(HolderRepository.class);

    TypeA simpleDeviceState = new TypeA();
    Holder<TypeA> holder = new Holder<>(simpleDeviceState);
    repository.save(holder);

    Holder holder1=repository.findAll().iterator().next();
    TypeA typeA= (TypeA) holder1.getType();

    System.out.println("Param: "+typeA.getParam());
    context.close();
}}

Pom 仅包含 org.springframework.boot::spring-boot-starter-data-jpa 和 com.h2database::h2。

打印点出现异常。我想我得到 org.hibernate.LazyInitializationException 因为 fetch = FetchType.EAGER 不起作用。

级联也仅适用于 PERSIST。也许是混合 Hibernate 和 JPA 的问题，但我无法处理它。提前致谢!

Answer 1

这不是一个好的解决方案，但它确实有效。但我想得到一个更好的。它是带有 @Transactional 和 Hibernate.initialize 的服务:

@Component
@Transactional
public class ServiceHolder {

@Autowired
HolderRepository holderRepository;

public Holder getH(long id) {
    Holder holder = holderRepository.findOne(id);
    Hibernate.initialize(holder.getType());
    return holder;
}

}