Question

我要做的是通过XML注入几乎与通过A @PersistenceContext注释完成的方式相同。我需要这个，因为我需要将不同的实体管理器注入到同一个DAO中。数据库彼此镜像，我宁愿有一个基类，对于那个基类的实例，然后创建多个类，这样我就可以使用@PersistenceContext注释。

这是我的例子。这就是我现在正在做的事情并且有效。

public class ItemDaoImpl {
 protected EntityManager entityManager;

 public List<Item> getItems() {
     Query query = entityManager.createQuery("select i from Item i");
  List<Item> s = (List<Item>)query.getResultList();
  return s; 
 }
 public void setEntityManger(EntityManager entityManager) {
  this.entityManager = entityManager;
 }
}

@Repository(value = "itemDaoStore2")
public class ItemDaoImplStore2 extends ItemDaoImpl {

 @PersistenceContext(unitName = "persistence_unit_2")
 public void setEntityManger(EntityManager entityManager) {
  this.entityManager = entityManager;
 }
}

@Repository(value = "itemDaoStore1")
public class ItemDaoImplStore1 extends ItemDaoImpl {

 @PersistenceContext(unitName = "persistence_unit_1")
 public void setEntityManger(EntityManager entityManager) {
  this.entityManager = entityManager;
 }
}

TransactionManagers，EntityManagers定义如下......

<!-- Registers Spring's standard post-processors for annotation-based configuration like @Repository -->
<context:annotation-config />

<!-- For @Transactional annotations -->
<tx:annotation-driven transaction-manager="transactionManager1"  />
<tx:annotation-driven transaction-manager="transactionManager2"  />

<!-- This makes Spring perform @PersistenceContext/@PersitenceUnit injection: -->
<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>

<!-- Drives transactions using local JPA APIs -->
<bean id="transactionManager1" class="org.springframework.orm.jpa.JpaTransactionManager">
 <property name="entityManagerFactory" ref="entityManagerFactory1" />
</bean>

<bean id="transactionManager2" class="org.springframework.orm.jpa.JpaTransactionManager">
 <property name="entityManagerFactory" ref="entityManagerFactory2" />
</bean>

<bean id="entityManagerFactory1" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
 <property name="persistenceUnitName" value="persistence_unit_1"/>
...
</bean>

<bean id="entityManagerFactory2" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
 <property name="persistenceUnitName" value="persistence_unit_2"/>
...
</bean>

我想要做的是不要创建ItemDaoImplStore2或ItemDaoImplStore1类。我希望通过xml将这些作为ItemDaoImpl的实例。我不知道如何正确地注入实体管理器。我想模拟将其注释为“存储库”注释，并且我还希望能够通过持久性单元名称指定要注入的entityManager。我希望使用XML代替类似下面的内容。

 <!-- Somehow annotate this instance as a @Repository annotation -->
 <bean id="itemDaoStore1" class="ItemDaoImpl">
  <!-- Does not work since it is a LocalContainerEntityManagerFactoryBean-->
  <!-- Also I would perfer to do it the same way PersistenceContext works
   and only provide the persistence unit name.  I would like to be
   able to specify persistence_unit_1-->
  <property name="entityManager"  ref="entityManagerFactory1"/> 
 </bean>

  <!-- Somehow annotate this instance as a @Repository annotation -->
 <bean id="itemDaoStore2" class="ItemDaoImpl">
  <!-- Does not work since it is a LocalContainerEntityManagerFactoryBean-->
  <!-- Also I would perfer to do it the same way PersistenceContext works
   and only provide the persistence unit name.  I would like to be
   able to specify persistence_unit_2-->
  <property name="entityManager"  ref="entityManagerFactory2"/> 
 </bean>

Answer 1

使用SharedEntityManagerBean - 它为EntityManager创建共享EntityManagerFactory，方式与@PersistenceContext相同：

<bean id="itemDaoStore1" class="ItemDaoImpl"> 
    <property name="entityManager">
        <bean class = "org.springframework.orm.jpa.support.SharedEntityManagerBean">
            <property name = "entityManagerFactory" ref="entityManagerFactory1"/>  
        </bean>
    </property>
</bean>

Answer 2

您可以使用SharedEntityManagerBean在xml配置中提供持久性单元名称，如下所示：

<bean id="testDao" class="com.test.persistence.dao.BaseDAO">
    <property name="entityManager">
        <bean class="org.springframework.orm.jpa.support.SharedEntityManagerBean">
            <property name="persistenceUnitName" value="persistence-test-unit" />
        </bean>
    </property>
</bean>

当然，您可以将SharedEntityManagerBean作为单独的bean

在这里，我正在使用entityManager

将BaseDAO注入@PersistenceContext(unitName="...")

通过XML而不是注释注入Entitymanager

2 个答案: