EAP7.3 JPA+Hibernate REST双向ManyToOne关系序列化(非SPRING)
EAP7.3 JPA+Hibernate REST双向ManyToOne关系序列化(非SPRING)
提问于 2020-08-26 15:52:48
我来自Payara/EclipseLink背景，在这里，这只是一个现成的工作环境。我的合同要求我使用不支持EclipseLink.persistance的EAP，我总是喜欢“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，它的关系非常简单。然而，当我试图访问一个对象时，我会得到一个序列化错误(下面的细节)。
实体一
@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另一边也会出现同样的错误。在使用EclipseLink时，这是完全可以接受的，我已经尝试了几天，但是我看到的每一个例子似乎都没有解决我的具体问题。
为了清晰起见，以下是实体1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);
}
}实体一的持续管理人员
@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);
}
}
}回答 2
Stack Overflow用户
回答已采纳
发布于 2020-08-26 20:20:52
按照规范，您的管理器EJB查找所有实体并将其加载到返回的列表中，但JPA默认列表(如实体中的分类)为惰性加载字段。
当您的findAll方法返回时，没有更多的事务，列表中的实体变成了从EntityManager中分离出来的。因此，实体管理器不能加载每个分类字段的内容以允许序列化。
您可能会使用一些内部属性更改实体管理器的行为，甚至将您的分类字段定义为急切获取，但当您使用TrainingCenterEntity而不访问分类字段时，这可能会导致性能问题(每次您得到一个中心时都会从数据库中检索分类)。
最好的方法是将命名查询更改为使用approach：
@NamedQuery(name = TrainingCenterEntity.findAll, query = "SELECT c FROM TrainingCenterEntity c JOIN FETCH c.classifications")JOIN FETCH允许JPA急切地获取其他延迟加载的字段的内容。
请注意：
- 任何findAll方法都倾向于公开大量数据；以及
- JSON序列化库的某些实现不够智能，无法检测循环关系，因此您的分类->培训中心如果在序列化时没有正确注释为忽略(@JsonIgnore )，可能会导致堆栈溢出。
您的代码在使用EclipseLink时不会出现问题，这可能是因为您的实体在执行之前并不是静态编织。EclipseLink的一些默认配置还允许在一些不同的场景中加载延迟字段，即使使用静态编织的延迟加载定义也是如此。在hibernate中，编织被称为字节码增强，它是自动生成的。
Stack Overflow用户
发布于 2022-01-12 10:47:28
在返回集合的方法中添加@Jsonb瞬态注释。
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原文链接：
https://stackoverflow.com/questions/63601273
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