6
Ho le classi di entità menzionate di seguito, quando eseguo la mia applicazione ottengo la seguente eccezione. Alcune delle altre domande simili non hanno risolto il problema.Hibernate org.hibernate.LazyInitializationException: impossibile inizializzare in modo lento una raccolta di ruoli:
WARNING: StandardWrapperValve[jersey-serlvet]: PWC1406: Servlet.service()
for servlet jersey-serlvet threw exception
org.hibernate.LazyInitializationException: failed to lazily initialize
a collection of role: test.entity.Dept.empDeptno, no session
or session was closed
at org.hibernate.collection.internal.AbstractPersistentCollection.
throwLazyInitializationException(AbstractPersistentCollection.java:393)
at org.hibernate.collection.internal.AbstractPersistentCollection.
throwLazyInitializationExceptionIfNotConnected
(AbstractPersistentCollection.java:385)
at org.hibernate.collection.internal.AbstractPersistentCollection.
initialize(AbstractPersistentCollection.java:378)
Come posso risolvere questo problema?
Emp entità
@Entity
@Table(name = "EMP", schema = "SCOTT"
)
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Emp.findAllEmployees", query = "select e from Emp e left
join fetch e.deptNo order by e.empno desc")
})
public class Emp implements java.io.Serializable {
@Id
@Column(name = "EMPNO", unique = true, nullable = false, precision = 4,
scale = 0)
private short empno;
@ManyToOne
@JoinColumn(name = "DEPTNO", referencedColumnName = "DEPTNO")
private Dept deptNo;
Dipartimento entità
@Entity
@Table(name = "DEPT", schema = "SCOTT"
)
@XmlRootElement
public class Dept implements java.io.Serializable {
@Id
@Column(name = "DEPTNO", unique = true, nullable = false, precision = 2,
scale = 0)
private short deptno;
@OneToMany(fetch=FetchType.LAZY,mappedBy = "deptNo")
private Set<Emp> empDeptno;
DAOImpl
@Override
public List<Emp> findAllEmployees() {
return getEntityManager().createNamedQuery("Emp.findAllEmployees",
Emp.class).getResultList();
}
Jersey servizio RESTful
@Component
@Path("/employee")
public class EmployeeRestService {
@Autowired
EmployeeService employeeService;
@GET
@Produces({MediaType.APPLICATION_JSON})
public List<Emp> getEmployees() {
List<Emp> emp = new ArrayList<Emp>();
emp.addAll(getEmployeeService().findAllEmployees());
return emp;
}
Primavera applicationContext.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd"
>
<!-- Data Source Declaration -->
<bean id="DataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="jdbc/scottDS"/>
</bean>
<context:component-scan base-package="net.test" />
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="DataSource" />
<property name="packagesToScan" value="net.test" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="false" />
<property name="generateDdl" value="false" />
<property name="databasePlatform" value="${jdbc.dialectClass}" />
</bean>
</property>
</bean>
<bean id="defaultLobHandler" class="org.springframework.jdbc.support.lob.DefaultLobHandler" />
<!-- Transaction Config -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<tx:annotation-driven transaction-manager="transactionManager"/>
<context:annotation-config/>
<bean id="hibernateStatisticsMBean" class="org.hibernate.jmx.StatisticsService">
<property name="statisticsEnabled" value="true" />
<property name="sessionFactory" value="#{entityManagerFactory.sessionFactory}" />
</bean>
</beans>
avete provato l'accesso alla raccolta mentre la sessione è ancora disponibile? Potresti comunque ricevere un oggetto proxy, quindi richiamare una semplice operazione su di esso, come 'size()' – kostja
@kostja Sto chiamando il metodo dal servizio RESTful, ho pubblicato il mio servizio RESTful e lo snippet di codice DAOImpl modificando la mia domanda. – user75ponic
potresti voler cambiare 'FetchType' del campo' empDetno' in 'EAGER'. Una soluzione meno pulita sarebbe quella di attivare il caricamento dell'impostazione 'empDet' nel metodo' findAllEmployees' accedendovi. – kostja