通过 XML 而不是注解注入 Entitymanager [英] Injecting Entitymanager via XML and not annnotations

问题描述

我想要做的是通过 XML 注入几乎与通过 @PersistenceContext 注释完成的相同的方式.我需要这个，因为我需要将不同的实体管理器注入同一个 DAO.数据库彼此镜像，我宁愿有 1 个基类，然后为该基类的实例创建多个类，以便我可以使用 @PersistenceContext 注释.

What I am trying to do is inject through XML almost the same way that is done through A @PersistenceContext annotation. I am in need of this because of the fact I have different entity managers I need to inject into the same DAO. The databases mirror one another and I would rather have 1 base class and for instances of that base class then create multiple classes just so I can use the @PersistenceContext annotation.

这是我的例子.这就是我现在正在做的事情，而且很有效.

Here is my example. This is what I am doing now and it works.

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...

TransactionManagers, EntityManagers are defined below...

<!-- 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>

我想要做的是不创建类 ItemDaoImplStore2 或 ItemDaoImplStore1.我想通过 xml 将这些作为 ItemDaoImpl 的实例.我不知道如何正确注入实体管理器.我想模拟将此注释为存储库"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.我想要使​​用 XML 代替类似于下面的内容.

What I want to do is to NOT create classes ItemDaoImplStore2 or ItemDaoImplStore1. I want to have these as instances of ItemDaoImpl via xml instead. I do not know how to inject the entitymanager properly though. I want to simulate annotating this as a 'Repository' annotation, and I also want to be able to specify what entityManager to inject by the persistence unit name. I want something similar to the below using XML instead.

 <!-- 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>

推荐答案

Use SharedEntityManagerBean - 它为 EntityManagerFactory 创建一个共享的 EntityManager@PersistenceContext:

Use SharedEntityManagerBean - it creates a shared EntityManager for EntityManagerFactory the same way as @PersistenceContext:

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

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