我使用spring 4与hibernate 4和JPA进行了数据库连接。当我尝试获得一个懒惰的初始化字段时,我得到了一个LazyInitializationException。Spring 4 hibernate 4 JPA LazyInitializationException:未能延迟初始化角色集合
我的applicationContext.xml:
<context:annotation-config />
<context:component-scan base-package="xy" />
<jpa:repositories base-package="xy.repositories" />
<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="punit" />
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="true" />
</bean>
</property>
<property name="jpaPropertyMap">
<map>
<entry key="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
<entry key="hibernate.hbm2ddl.auto" value="update" />
<entry key="hibernate.format_sql" value="true" />
</map>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true" />
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/keysystem" />
<property name="username" value="username" />
<property name="password" value="password" />
</bean>
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>
型号:
@Entity
@Table
public class Employee {
@Id
@GeneratedValue
private long employeeId;
private String firstName;
private String lastName;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "employee")
@Cascade(CascadeType.ALL)
@Fetch(FetchMode.SELECT)
private Set<Legitimacy> legitimacies;
...
我发现只有MVC过滤解决方案,但我不使用MVC。我试过Hibernate.initialize(...)和@Transational,@Fetch注解,但这些都没有解决我的问题。
这里是堆栈跟踪:当您尝试访问原始会话外的引用对象发生
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: xy.Employee.legitimacies, could not initialize proxy - no Session
at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:575)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:214)
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:554)
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:142)
at org.hibernate.collection.internal.PersistentSet.iterator(PersistentSet.java:180)
... 64 more
http://stackoverflow.com/questions/33318404/jpa-how-to-return-null-instead-of-lazyinitializationexception/33325493#33325493 接受的答案解释了它为什么会发生以及如何解决它。如果您尝试访问'legitimacies'的内容,那么在事务尚未完全初始化的情况下设置事务外,您将无法获得此异常。 –
@Transactional注释对我不起作用,我不想使用Eager初始化,因为它的性能。 – Faraine
然后我认为你应该再提供两个代码部分,以便我们可以确定确切的问题以及如何解决它。请添加您用于获取Employee对象的代码,以及您尝试访问合法性设置内容的代码。你可以做的是在休眠会话仍然打开时初始化Set。 –