1

背景

我正在尝试使用 Apache-CXF 实现一个 RESTful Web 服务,该服务与数据库交互以通过 Hibernate 执行一些 CRUD 操作。Web 服务使用 Jackson JAX-RS Provider 使用和生成 JSON 格式的对象。

我目前收到“无法延迟初始化集合......没有关闭会话或会话”异常,当它尝试序列化响应对象时,它从 Jackson 提供程序冒泡。

我假设如果我标记了服务方法,@Transactional那么当杰克逊提供者序列化响应时,该会话将可供杰克逊提供者使用,但情况似乎并非如此。

问题

当杰克逊在序列化期间行走对象时,如何使休眠会话可用?

我试过的

弹簧配置

<context:component-scan base-package="com.db.cif.mapper" />
<context:component-scan base-package="com.db.cif.mapper.repository" />
<context:annotation-config />

<tx:jta-transaction-manager>
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</tx:jta-transaction-manager>

<tx:annotation-driven />

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="persistenceUnitName" value="cifmapper" />
    <property name="jpaDialect">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
    </property>
</bean>

<!-- JAX-RS Configuration -->
<jaxrs:server id="mappingService" address="/">
    <jaxrs:serviceBeans>
        <ref bean="mappingServiceBean" />
    </jaxrs:serviceBeans>
    <jaxrs:extensionMappings>
        <entry key="json" value="application/json" />
    </jaxrs:extensionMappings>
    <jaxrs:providers>
        <ref bean="jsonProvider" />
    </jaxrs:providers>
</jaxrs:server>

<bean id="mappingServiceBean" class="com.db.cif.mapper.MappingService" />

<bean id="jsonProvider" class="org.codehaus.jackson.jaxrs.JacksonJsonProvider" />

服务豆

@Service("mappingService")
@Transactional
public class MappingService 
{
    private static final Logger logger = Logger.getLogger(MappingService.class);

    @Autowired
    @Qualifier("mappingRepository")
    private MappingRepository mappingRepository;

    @GET
    @Path("/collections/{id}")
    @Produces(MediaType.APPLICATION_JSON)
    public Collection getCollection(@PathParam("id") String id)
    {
        if(logger.isDebugEnabled())
        {
            logger.debug(String.format("Invoked getCollection, Collection id: %s", id));
        }

        return this.mappingRepository.getCollection(id);
    }

    @POST
    @Path("/collections/")
    @Consumes(MediaType.APPLICATION_JSON)
    public Response addCollection(Collection collection)
    {
        if(logger.isDebugEnabled())
        {
            logger.debug(String.format("Invoked addCollection, Collection: %s", collection));
        }

        this.mappingRepository.createCollection(collection);

        return Response.ok(collection).build();
    }
}

收集豆

@Entity
@Table(schema = "CIFMAPPER", name = "COLLECTION")
public class Collection implements Serializable
{
    private static final long serialVersionUID = 1579878442412232635L;

    @Id
    @Column(name = "ID")
    private String id;

    @Column(name = "SRC_ENDPT_ID", nullable = false, insertable = false, updatable = false)
    private long sourceEndpointId;

    @Column(name = "DEST_ENDPT_ID", nullable = false, insertable = false, updatable = false)
    private long destinationEndpointId;

    @Column(name = "DESCRIPTION")
    private String description;

    @Column(name = "START_DATE", nullable = false)
    private Date startDate;

    @Column(name = "END_DATE")
    private Date endDate;

    @ManyToOne(optional = false)
    @JoinColumn(name = "SRC_ENDPT_ID")
    private Endpoint source;

    @ManyToOne(optional = false)
    @JoinColumn(name = "DEST_ENDPT_ID")
    private Endpoint destination;

    @OneToMany(mappedBy = "collection", targetEntity = MappingGroup.class, fetch = FetchType.EAGER)
    private List<MappingGroup> mappingGroups;

//Getters and Setters Removed For Brevity
}
4

1 回答 1

5

虽然我相信有一种方法可以使这项工作(使用Filter打开和关闭会话的或拦截器),但我认为正确的答案是:不要使用惰性集合和代理。配置您的映射,以便您没有惰性集合。

另一种方法是手动初始化它们。这通常与 DTO 结合使用 - 具有与实体相似结构的对象,这些对象用作对其他组件的响应(这样您就不会直接公开实体)。因此,您的方法返回OrderDTO而不是Order,其中 DTO 包含返回给调用者所需的尽可能多的字段。您手动将值从实体传输到 DTO。

于 2012-03-06T21:27:37.950 回答