使用 Jackson 序列化 Collection 时出现 LazyInitializationException
LazyInitializationException when serializing Collection with Jackson
我正在使用 AngularJs 和 Rest 服务 (RestEasy) 构建一个应用程序，我需要在其中显示产品列表。当用户单击其中一种产品时加载列表后，将加载该产品的详细信息和图像。
我不想在显示所有产品的列表时加载与产品相关联的集合（即图片），但仅当我需要其中一个产品的详细信息时，出于性能原因，所以我使用延迟加载。
Hibernate 运行良好，我可以看到最初我只加载了一些属性而不是集合，但是在其余服务中，当 Jackson 尝试访问集合以对其进行序列化时，我得到了这个著名的异常：
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.domainmodel.Product.Images
当然那一刻不再有Session打开，数据库事务已经提交。我不想让会话保持打开状态。所以在网上搜索我看到我们可以告诉 Jackson 不要使用注释 @JsonIgnore 序列化 属性。
这个注释必须放在实体（POJO）的 属性 或 getter 中，所以基本上，如果我告诉 Jackson 在序列化到 JSON 时不要序列化这个集合，它就会解决这个问题是暂时的，但是一旦我需要用集合加载产品，因为用户点击了它，它就不会序列化集合，所以我稍后会遇到这个问题。所以我不认为这对我来说是一个解决方案。关于如何解决这种情况的任何想法和建议？我post实体的代码和其他服务在这里。提前致谢！！
@Entity
@Table(name = "PRODUCTS")
public class Product implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID")
private Long id;
@Column(name = "PATH_TO_IMAGE", nullable = false, insertable = true, updatable = true)
private String pathToImage;
@Column(name="DESCRIPTION",nullable=true, insertable = true, updatable = true)
private String description;
@ManyToOne(optional = false)
@JoinColumn(name = "XID_PRODUCT_TYPE", nullable = false, insertable = false, updatable = false)
private ProductType productType;
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(
name = "PRODUCT_IMAGE",
joinColumns = {@JoinColumn(name = "XID_PRODUCT", referencedColumnName = "ID")},
inverseJoinColumns = {@JoinColumn(name = "XID_IMAGE", referencedColumnName = "ID")})
private List<Image> images;
... getters and setters
}
然后是其余服务的代码：
@Path("/products")
public class ProductsService extends CommonService{
private static final Logger log = Logger.getLogger(ProductsService.class);
@EJB
private ProductsServiceHandler handler;
@GET
@Produces(MediaType.APPLICATION_JSON)
public Response getAllProducts(@Context Request request, @Context HttpHeaders httpHeaders)
{
try
{
List<Product> products=handler.findAllProducts();
return Response.ok(products).header(ALLOW_ORIGIN_HEADER, "*").build();
}
catch(Exception e){return Response.status(Status.INTERNAL_SERVER_ERROR).build();}
}
}
请求的完整堆栈跟踪：
2015-02-03 00:35:41,085 ERROR [io.undertow.request] (default task-9) UT005023: Exception handling request to /arenaclub/rest/products: org.jboss.resteasy.spi.UnhandledException: Response is committed, can't handle exception
at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:148) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:432) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:376) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51) [resteasy-jaxrs-3.0.8.Final.jar:]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [jboss-servlet-api_3.1_spec-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access[=13=]0(ServletInitialHandler.java:73) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleRequest(ServletInitialHandler.java:146) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:177) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.HttpServerExchange.run(HttpServerExchange.java:727) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [rt.jar:1.8.0_25]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [rt.jar:1.8.0_25]
at java.lang.Thread.run(Thread.java:745) [rt.jar:1.8.0_25]
Caused by: com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.fgonzalez.domainmodel.Product.images, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.fgonzalez.domainmodel.Product["images"])
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:232) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:197) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.StdSerializer.wrapAndThrow(StdSerializer.java:187) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:652) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:100) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:610) [jackson-databind-2.3.2.jar:2.3.2]
at org.jboss.resteasy.plugins.providers.jackson.ResteasyJackson2Provider.writeTo(ResteasyJackson2Provider.java:186) [resteasy-jackson2-provider-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.writeTo(AbstractWriterInterceptorContext.java:129) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.ServerWriterInterceptorContext.writeTo(ServerWriterInterceptorContext.java:62) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:118) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.security.doseta.DigitalSigningInterceptor.aroundWriteTo(DigitalSigningInterceptor.java:143) [resteasy-crypto-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:122) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor.aroundWriteTo(GZIPEncodingInterceptor.java:100) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:122) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:99) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:427) [resteasy-jaxrs-3.0.8.Final.jar:]
... 32 more
您可以 运行 Jackson 在 JPA 会话中，这样延迟加载就可以了。
您可以做几件事。
- 最快的方法 - 遍历
products 并在 return 计算结果 之前对每个产品调用 setImages(null)
- 为
Product 注册两个自定义 JSON 序列化器，一个会序列化图像，一个不会，然后根据调用的服务选择序列化器。问题是我不确定这可以用 RestEasy 完成，但请查看 this thread 以获得一些提示
- 不要 return 来自 REST 服务的实体 bean，而是使用 DTO，这样您就可以轻松地控制 return 的内容和格式。另一大优点是您将 REST 层与实体 bean 分离，这使您可以自由更改实体，而不必担心更改 REST 用户期望的格式。这将是首选。
您可以考虑两种可能的选择：
- 为您的服务层使用单独的数据传输对象 (DTO)，因此您将在实体-> DTO期间管理获取所需信息转换。这种方法的缺点 - 您需要编写和维护这些转换器。另一方面，您可以完全灵活地将任何实体组合到您的服务响应中。首选。
- 创建单独的轻量级实体（例如"ProductInfo"）用于"products"调用。将多个实体映射到一个数据库应该没有任何问题 table。
Jackson 项目的人们开发了一个很好的模块来解决这个问题！
在 github 上查看：
https://github.com/FasterXML/jackson-datatype-hibernate
我正在使用 AngularJs 和 Rest 服务 (RestEasy) 构建一个应用程序，我需要在其中显示产品列表。当用户单击其中一种产品时加载列表后，将加载该产品的详细信息和图像。
我不想在显示所有产品的列表时加载与产品相关联的集合（即图片），但仅当我需要其中一个产品的详细信息时，出于性能原因，所以我使用延迟加载。
Hibernate 运行良好，我可以看到最初我只加载了一些属性而不是集合，但是在其余服务中，当 Jackson 尝试访问集合以对其进行序列化时，我得到了这个著名的异常：
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.domainmodel.Product.Images
当然那一刻不再有Session打开，数据库事务已经提交。我不想让会话保持打开状态。所以在网上搜索我看到我们可以告诉 Jackson 不要使用注释 @JsonIgnore 序列化 属性。 这个注释必须放在实体（POJO）的 属性 或 getter 中，所以基本上，如果我告诉 Jackson 在序列化到 JSON 时不要序列化这个集合，它就会解决这个问题是暂时的，但是一旦我需要用集合加载产品，因为用户点击了它，它就不会序列化集合，所以我稍后会遇到这个问题。所以我不认为这对我来说是一个解决方案。关于如何解决这种情况的任何想法和建议？我post实体的代码和其他服务在这里。提前致谢！！
@Entity
@Table(name = "PRODUCTS")
public class Product implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID")
private Long id;
@Column(name = "PATH_TO_IMAGE", nullable = false, insertable = true, updatable = true)
private String pathToImage;
@Column(name="DESCRIPTION",nullable=true, insertable = true, updatable = true)
private String description;
@ManyToOne(optional = false)
@JoinColumn(name = "XID_PRODUCT_TYPE", nullable = false, insertable = false, updatable = false)
private ProductType productType;
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(
name = "PRODUCT_IMAGE",
joinColumns = {@JoinColumn(name = "XID_PRODUCT", referencedColumnName = "ID")},
inverseJoinColumns = {@JoinColumn(name = "XID_IMAGE", referencedColumnName = "ID")})
private List<Image> images;
... getters and setters
}
然后是其余服务的代码：
@Path("/products")
public class ProductsService extends CommonService{
private static final Logger log = Logger.getLogger(ProductsService.class);
@EJB
private ProductsServiceHandler handler;
@GET
@Produces(MediaType.APPLICATION_JSON)
public Response getAllProducts(@Context Request request, @Context HttpHeaders httpHeaders)
{
try
{
List<Product> products=handler.findAllProducts();
return Response.ok(products).header(ALLOW_ORIGIN_HEADER, "*").build();
}
catch(Exception e){return Response.status(Status.INTERNAL_SERVER_ERROR).build();}
}
}
请求的完整堆栈跟踪：
2015-02-03 00:35:41,085 ERROR [io.undertow.request] (default task-9) UT005023: Exception handling request to /arenaclub/rest/products: org.jboss.resteasy.spi.UnhandledException: Response is committed, can't handle exception
at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:148) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:432) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:376) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51) [resteasy-jaxrs-3.0.8.Final.jar:]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [jboss-servlet-api_3.1_spec-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access[=13=]0(ServletInitialHandler.java:73) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleRequest(ServletInitialHandler.java:146) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:177) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at io.undertow.server.HttpServerExchange.run(HttpServerExchange.java:727) [undertow-core-1.0.15.Final.jar:1.0.15.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [rt.jar:1.8.0_25]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [rt.jar:1.8.0_25]
at java.lang.Thread.run(Thread.java:745) [rt.jar:1.8.0_25]
Caused by: com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.fgonzalez.domainmodel.Product.images, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.fgonzalez.domainmodel.Product["images"])
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:232) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:197) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.StdSerializer.wrapAndThrow(StdSerializer.java:187) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:652) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:100) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114) [jackson-databind-2.3.2.jar:2.3.2]
at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:610) [jackson-databind-2.3.2.jar:2.3.2]
at org.jboss.resteasy.plugins.providers.jackson.ResteasyJackson2Provider.writeTo(ResteasyJackson2Provider.java:186) [resteasy-jackson2-provider-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.writeTo(AbstractWriterInterceptorContext.java:129) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.ServerWriterInterceptorContext.writeTo(ServerWriterInterceptorContext.java:62) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:118) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.security.doseta.DigitalSigningInterceptor.aroundWriteTo(DigitalSigningInterceptor.java:143) [resteasy-crypto-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:122) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor.aroundWriteTo(GZIPEncodingInterceptor.java:100) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:122) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:99) [resteasy-jaxrs-3.0.8.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:427) [resteasy-jaxrs-3.0.8.Final.jar:]
... 32 more
您可以 运行 Jackson 在 JPA 会话中，这样延迟加载就可以了。
您可以做几件事。
- 最快的方法 - 遍历
products并在 return 计算结果 之前对每个产品调用 - 为
Product注册两个自定义 JSON 序列化器，一个会序列化图像，一个不会，然后根据调用的服务选择序列化器。问题是我不确定这可以用 RestEasy 完成，但请查看 this thread 以获得一些提示 - 不要 return 来自 REST 服务的实体 bean，而是使用 DTO，这样您就可以轻松地控制 return 的内容和格式。另一大优点是您将 REST 层与实体 bean 分离，这使您可以自由更改实体，而不必担心更改 REST 用户期望的格式。这将是首选。
setImages(null)
您可以考虑两种可能的选择：
- 为您的服务层使用单独的数据传输对象 (DTO)，因此您将在实体-> DTO期间管理获取所需信息转换。这种方法的缺点 - 您需要编写和维护这些转换器。另一方面，您可以完全灵活地将任何实体组合到您的服务响应中。首选。
- 创建单独的轻量级实体（例如"ProductInfo"）用于"products"调用。将多个实体映射到一个数据库应该没有任何问题 table。
Jackson 项目的人们开发了一个很好的模块来解决这个问题！
在 github 上查看： https://github.com/FasterXML/jackson-datatype-hibernate