在春季应用程序中注入2(不久的将来)不同的EntityManagerFactory(或EntityManager)

Question

我有spring jpa（hibernate）项目，在该项目上，我将其连接到 MSSQL 数据库，现在我需要打开一个新连接，但是这次将是对于 mySQL 。我正在使用XML配置

<bean id="hibernateJpaVendorAdapter"
    class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource"
    destroy-method="close">
    <property name="driverClassName" value="${spring.datasource.driverClassName}" />
   ....
</bean>
<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
    p:dataSource-ref="dataSource" p:packagesToScan="com.wsg.admin.api.model"
    p:jpaVendorAdapter-ref="hibernateJpaVendorAdapter">
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.cache.use_second_level_cache">false</prop>
            ....
        </props>
    </property>
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<!-- Configure the MySQL connection -->
<bean id="enduserDataSource" class="org.apache.commons.dbcp2.BasicDataSource"
    destroy-method="close">
    <property name="driverClassName" value="${enduser.db.driver}" />
    ....
</bean>
<bean id="enduserEntityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
    p:dataSource-ref="enduserDataSource" p:packagesToScan="com.wsg.admin.api.model"
    p:jpaVendorAdapter-ref="hibernateJpaVendorAdapter">
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.cache.use_second_level_cache">false</prop>
            ....
        </props>
    </property>
</bean>
<tx:annotation-driven transaction-manager="enduserTransactionManager" />
<bean id="enduserTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="enduserEntityManagerFactory" />
</bean>

然后，我尝试使用片段注入EntityManager

@Autowired
EntityManager entityManager;

但是我得到了例外

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'brandServiceImpl': Unsatisfied dependency expressed through field 'entityManager'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'javax.persistence.EntityManager' available: expected single matching bean but found 2: org.springframework.orm.jpa.SharedEntityManagerCreator#0,org.springframework.orm.jpa.SharedEntityManagerCreator#1

Answer 1

由于您有两个Entity Manager（来自EntityMangaerFactory），因此您需要告诉Spring您想自动进行哪个Specifix EntityManager。使用@Qualifier

@Autowired  
@Qualifier("enduserEntityManagerFactory")  // use bean id of the Entity Manager Factory you want to inject
EntityManagerFactory entityManagerFactory
EntityManager entityManager = entityManagerFactory.createEntityManager();

在此处提供更多有关此的信息

Answer 2

修复。感谢@volceri我使用了答案https://stackoverflow.com/a/18073628/1973933，如下

将<property name="persistenceUnitName" value="appPU" />添加到entityManagerFactory

的每个

<bean id="entityManagerFactory" ...  >
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.cache.use_second_level_cache">false</prop>
            ...
        </props>
    </property>
    <property name="persistenceUnitName" value="dataSourcePU" />
</bean>
<bean id="endUserEntityManagerFactory" ...  >
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.cache.use_second_level_cache">false</prop>
            ...
        </props>
    </property>
    <property name="persistenceUnitName" value="enduserDataSourcePU" />
</bean>

并注入EM对象，我使用了

@PersistenceContext(unitName="dataSourcePU")
EntityManager entityManager;
@PersistenceContext(unitName="enduserDataSourcePU")
EntityManager endUserEntityManager;