实际上我的问题是当我使用entitymanager.unwrap（Session.class）时，
它会给出：java.lang.IllegalStateException: No transactional EntityManager available异常，甚至在方法声明中添加了@Transactional。
但是在我改变后它起作用了：
entitymanager.getEntityManagerFactory().createEntityManager().unwrap(Session.class)
我不知道为什么。有谁可以帮助我？
这是我用于entitymanager的配置。
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="persistenceUnit" />
<property name="dataSource" ref="bonecpDataSource" />
<property name="jpaDialect">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
</property>
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
</property>
<property name="packagesToScan">
<list>
<value>org.a.domain.entity.**.*</value>
</list>
</property>
<property name="jpaProperties">
<props>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.format_sql">true</prop>
<prop key="current_session_context_class">thread</prop>
<prop key="hibernate.jdbc.batch_size">50</prop>
<prop key="hibernate.cache.use_query_cache">false</prop>
<prop key="hibernate.cache.use_second_level_cache">false</prop>
<prop key="hibernate.generate_statistics">false</prop>
</props>
</property>
</bean>
<bean id="jpaTxManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<tx:annotation-driven transaction-manager="jpaTxManager"/>