java - EAP 7.3 JPA+Hibernate REST 双向 ManyToOne 关系序列化(非 SPRING)

转载作者：行者123 更新时间：2023-12-04 15:19:38

我来自 Payara/EclipseLink 背景，在这方面开箱即用。我的契约(Contract)要求我使用不支持 EclipseLink.persistance 的 EAP，我总是更喜欢“提供”而不是添加库。

我正在为我的对象创建一个非常简单的 REST 微服务，其中的关系非常简单。但是，当我尝试访问一个对象时，我遇到了一个序列化错误(详情如下)。

实体一号

@Entity
@Table(name = "training_centers")
@NamedQuery(name = TrainingCenterEntity.findAll, query = "SELECT c FROM TrainingCenterEntity c")
@JsonbVisibility(PrivateVisibilityStrategy.class)
public class TrainingCenterEntity implements Serializable, ValidEntity {

    private static final long serialVersionUID = 9197911968578298904L;
    public static final String PREFIX = "centers.entity.TrainingCenter.";
    public static final String findAll = PREFIX + "findAll";

    @Id
    @Column(name = "program_code")
    private String program_code;

    @Column(name = "program_name", length = 255, nullable = false)
    private String program_name;

    public TrainingCenterEntity(String code, String name) {
        this.program_code = code;
        this.program_name = name;
        this.classifications = new ArrayList<ClassificationEntity>();
    }
    
    public TrainingCenterEntity() {
        this.classifications = new ArrayList<ClassificationEntity>();
    }

    public String getProgramCode() {
        return program_code;
    }

    public void setProgramCode(String program_code) {
        this.program_code = program_code;
    }
    
    @OneToMany(
            fetch = FetchType.LAZY,
            cascade = CascadeType.ALL,
            orphanRemoval = true,
            mappedBy = "center")
    private List<ClassificationEntity> classifications;

实体二

@Entity
@Table(name = "classifications")
@NamedQueries({
    @NamedQuery(name = ClassificationEntity.findByProgramCode, query = "SELECT c FROM ClassificationEntity c WHERE c.center = :programCode"),
    @NamedQuery(name = ClassificationEntity.findAll, query = "SELECT c FROM ClassificationEntity c")
})
@JsonbVisibility(PrivateVisibilityStrategy.class)
public class ClassificationEntity implements Serializable, ValidEntity{
    
    private static final long serialVersionUID = 5138672261884252346L;
    public static final String PREFIX = "centers.entity.ClassificationEntity.";
    public static final String findByProgramCode = PREFIX + "findByProgramCode";
    public static final String findAll = PREFIX + "findAll";

    @Id
    @Column(name = "classification_id", columnDefinition = "serial")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(name = "classification_type", unique = true, nullable = false)
    private ClassificationType classificationType;
    
    @Column(name = "classification_name", nullable = true, length = 255)
    private String classificationName;
    
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "program_code", referencedColumnName = "program_code")
    private TrainingCenterEntity center;
    
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public ClassificationEntity() {
        this.center = new TrainingCenterEntity();
    }

实体一的REST端点

@GET
@Produces({MediaType.APPLICATION_JSON})
public List<TrainingCenterEntity> findAll() {
    return this.manager.findAll();
}

REST 端点的 StackTrace

11:44:03,129 SEVERE [org.eclipse.yasson.internal.Marshaller] (default task-1) Unable to serialize property 'classifications' from ptsi.service.centers.entity.TrainingCenterEntity
11:44:03,129 SEVERE [org.eclipse.yasson.internal.Marshaller] (default task-1) Generating incomplete JSON
11:44:03,129 INFO  [io.jaegertracing.internal.reporters.LoggingReporter] (default task-1) Span reported: 33fb13e2e5f679d8:33fb13e2e5f679d8:0:1 - GET:ptsi.service.centers.boundary.TrainingCenterResource.findAll
11:44:03,129 ERROR [io.undertow.request] (default task-1) UT005023: Exception handling request to /learning-hibernate/api/centers: org.jboss.resteasy.spi.UnhandledException: javax.ws.rs.ProcessingException: RESTEASY008205: JSON Binding serialization error javax.json.bind.JsonbException: Unable to serialize property 'classifications' from ptsi.service.centers.entity.TrainingCenterEntity
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:356)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:193)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:539)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:461)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:229)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:135)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:356)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:138)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:215)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:227)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
    at javax.servlet.api@2.0.0.Final-redhat-00001//javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
    at io.opentracing.contrib.opentracing-jaxrs2//io.opentracing.contrib.jaxrs2.server.SpanFinishingFilter.doFilter(SpanFinishingFilter.java:52)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:68)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:269)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:78)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:133)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:130)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1541)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1541)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1541)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1541)
    at org.wildfly.extension.undertow@7.3.1.GA-redhat-00003//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1541)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:249)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:78)
    at io.undertow.servlet@2.0.30.SP3-redhat-00001//io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:99)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.Connectors.executeRootHandler(Connectors.java:376)
    at io.undertow.core@2.0.30.SP3-redhat-00001//io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
    at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1982)
    at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at org.jboss.threads@2.3.3.Final-redhat-00001//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: javax.ws.rs.ProcessingException: RESTEASY008205: JSON Binding serialization error javax.json.bind.JsonbException: Unable to serialize property 'classifications' from ptsi.service.centers.entity.TrainingCenterEntity
    at org.jboss.resteasy.resteasy-json-binding-provider@3.11.2.Final-redhat-00002//org.jboss.resteasy.plugins.providers.jsonb.JsonBindingProvider.writeTo(JsonBindingProvider.java:160)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.writeTo(AbstractWriterInterceptorContext.java:137)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.ServerWriterInterceptorContext.writeTo(ServerWriterInterceptorContext.java:61)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:124)
    at org.jboss.resteasy.resteasy-crypto@3.11.2.Final-redhat-00002//org.jboss.resteasy.security.doseta.DigitalSigningInterceptor.aroundWriteTo(DigitalSigningInterceptor.java:147)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:129)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.ServerResponseWriter.lambda$writeNomapResponse$2(ServerResponseWriter.java:151)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.interception.ContainerResponseContextImpl.filter(ContainerResponseContextImpl.java:398)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.ServerResponseWriter.executeFilters(ServerResponseWriter.java:219)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:95)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:69)
    at org.jboss.resteasy.resteasy-jaxrs@3.11.2.Final-redhat-00002//org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:530)
    ... 58 more
Caused by: javax.json.bind.JsonbException: Unable to serialize property 'classifications' from ptsi.service.centers.entity.TrainingCenterEntity
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.ObjectSerializer.serializeInternal(ObjectSerializer.java:67)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serialize(AbstractContainerSerializer.java:64)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serializerCaptor(AbstractContainerSerializer.java:96)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serializeItem(AbstractContainerSerializer.java:157)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.CollectionSerializer.serializeInternal(CollectionSerializer.java:39)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.CollectionSerializer.serializeInternal(CollectionSerializer.java:27)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serialize(AbstractContainerSerializer.java:64)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.Marshaller.serializeRoot(Marshaller.java:148)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.Marshaller.marshall(Marshaller.java:76)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.Marshaller.marshall(Marshaller.java:102)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.JsonBinding.toJson(JsonBinding.java:118)
    at org.jboss.resteasy.resteasy-json-binding-provider@3.11.2.Final-redhat-00002//org.jboss.resteasy.plugins.providers.jsonb.JsonBindingProvider.writeTo(JsonBindingProvider.java:156)
    ... 69 more
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: ptsi.service.centers.entity.TrainingCenterEntity.classifications, could not initialize proxy - no Session
    at org.hibernate@5.3.16.Final-redhat-00001//org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:602)
    at org.hibernate@5.3.16.Final-redhat-00001//org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:217)
    at org.hibernate@5.3.16.Final-redhat-00001//org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:581)
    at org.hibernate@5.3.16.Final-redhat-00001//org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:148)
    at org.hibernate@5.3.16.Final-redhat-00001//org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:390)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.CollectionSerializer.serializeInternal(CollectionSerializer.java:38)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.CollectionSerializer.serializeInternal(CollectionSerializer.java:27)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serialize(AbstractContainerSerializer.java:64)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.AbstractContainerSerializer.serializerCaptor(AbstractContainerSerializer.java:96)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.ObjectSerializer.marshallProperty(ObjectSerializer.java:110)
    at org.eclipse.yasson@1.0.5.redhat-00001//org.eclipse.yasson.internal.serializer.ObjectSerializer.serializeInternal(ObjectSerializer.java:65)
    ... 80 more

另一边出现同样的错误。当使用 EclipseLink 时，它开箱即用，我已经尝试了几天，但我看到的每个示例似乎都没有解决我的具体问题。

为清楚起见，这里是实体一号的边界代码

实体一的资源

@Stateless
@Path("centers")
public class TrainingCenterResource {
    
    @Inject
    TrainingCenterManager manager;

    // POST should return 201 with Location URI in header
    @POST
    @Consumes({MediaType.APPLICATION_JSON})
    public Response save(TrainingCenterEntity center, @Context UriInfo info) {
        TrainingCenterEntity saved = this.manager.save(center);
        String id = saved.getProgramCode();
        URI uri = info.getAbsolutePathBuilder().path("/" + id).build();
        return Response.created(uri).build();
    }

    @GET
    @Path("{id}")
    @Produces({MediaType.APPLICATION_JSON})
    public Response find(@PathParam("id") String id) {
        TrainingCenterEntity center = this.manager.findById(id);
        if (center != null) {
            return Response.ok(center).build();
        }
        else {
            return Response.status(Response.Status.NOT_FOUND).build();
        }
    }
    
    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public List<TrainingCenterEntity> findAll() {
        return this.manager.findAll();
    }

    @PUT
    @Path("{id}")
    @Consumes({MediaType.APPLICATION_JSON})
    @Produces({MediaType.APPLICATION_JSON})
    public TrainingCenterEntity update(@PathParam("id") String id, TrainingCenterEntity center) {
        center.setProgramCode(id);
        return this.manager.save(center);
    }

    @DELETE
    @Path("{id}")
    public void delete(@PathParam("id") String id) {
        this.manager.delete(id);
    }
}

实体一的持久性管理器

@Stateless
public class TrainingCenterManager {

    @Inject
    private Logger LOGGER;

    @Inject
    private EntityManager em;

    
    public TrainingCenterEntity save(TrainingCenterEntity center) {
        try {
            return this.em.merge(center);
        } catch (PersistenceException pex) {
            LOGGER.log(Level.FINE, pex.toString(), pex);
            return null;
        }
    }
    
    public TrainingCenterEntity findById(String code) {
        try {
            return this.em.find(TrainingCenterEntity.class, code);
        } catch (Exception e) {
            LOGGER.log(Level.FINE, e.toString(), e);
            return null;
        }
    }
    
    public List<TrainingCenterEntity> findAll() {
        try {
            return this.em.createNamedQuery(TrainingCenterEntity.findAll, TrainingCenterEntity.class).getResultList();
        } catch (Exception e) {
            LOGGER.log(Level.FINE, e.toString(), e);
            return null;
        }
    }
    
    public void delete(String code) {
        try {
            TrainingCenterEntity reference = this.em.getReference(TrainingCenterEntity.class, code);
            this.em.remove(this.em.merge(reference));
        } catch (PersistenceException pex) {
            LOGGER.log(Level.FINE, pex.toString(), pex);
        }
    }
}

最佳答案

根据规范，您的管理器 EJB 会找到所有实体，然后加载到返回的列表中，但 JPA 默认列表(例如实体中的分类)作为延迟加载字段。

当您的 findAll 方法返回时，不再有事务并且列表中的实体从 EntityManager 中分离。因此，实体管理器无法加载每个分类字段的内容以允许序列化。

您可以使用一些内部属性更改您的实体管理器的行为，甚至可以将您的分类字段定义为急切获取，但是当您使用 TrainingCenterEntity 而不访问分类字段时，这可能会导致性能问题(分类将从数据库中检索)每次你得到一个中心)。

最好的方法是将命名查询更改为使用 JOIN FETCH:

@NamedQuery(name = TrainingCenterEntity.findAll, query = "SELECT c FROM TrainingCenterEntity c JOIN FETCH c.classifications")

JOIN FETCH 允许 JPA 预先获取延迟加载字段的内容。

请注意:

任何 findAll 方法都倾向于暴露大量数据；和
JSON 序列化库的某些实现不够智能，无法检测循环关系，因此如果未正确注释为在序列化时被忽略(@JsonIgnore 在 Jackson 案例中)，您的分类 -> trainingcenter 可能会导致堆栈溢出。

您的代码使用 EclipseLink 时没有问题，可能是因为您的实体不是 static weaved执行前。 EclipseLink 的一些默认配置还允许在一些不同的场景中加载惰性字段，即使使用静态编织的惰性加载定义也是如此。在 hibernate 状态下，编织称为 bytecode enhancement它是自动生成的。

关于java - EAP 7.3 JPA+Hibernate REST 双向 ManyToOne 关系序列化(非 SPRING)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/63601273/

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