使用Spring时如何注入多个JPA EntityManager(持久性单元) [英] How to inject multiple JPA EntityManager (persistence units) when using Spring

问题描述

我需要使用一个数据库进行查询(非修改)，而使用一个数据库进行命令(修改).我正在使用Spring Data JPA，所以我有两个配置类:

I need to use one database for queries (non-modifying) and one for commands (modifying). I am using Spring Data JPA, so I have two configuration classes:

@Configuration
@EnableJpaRepositories(value = "com.company.read",
        entityManagerFactoryRef = "readingEntityManagerFactory",
        transactionManagerRef = "readingTransactionManager")
@EnableTransactionManagement
public class SpringDataJpaReadingConfiguration {

    @Bean(name = "readingEntityManagerFactory")
    public EntityManagerFactory readingEntityManagerFactory() {
        return Persistence.createEntityManagerFactory("persistence.reading");
    }

    @Bean(name = "readingExceptionTranslator")
    public HibernateExceptionTranslator readingHibernateExceptionTranslator() {
        return new HibernateExceptionTranslator();
    }

    @Bean(name = "readingTransactionManager")
    public JpaTransactionManager readingTransactionManager() {
        return new JpaTransactionManager();
    }

}

@Configuration
@EnableJpaRepositories(value = "com.company.write",
        entityManagerFactoryRef = "writingEntityManagerFactory",
        transactionManagerRef = "writingTransactionManager")
@EnableTransactionManagement
public class SpringDataJpaWritingConfiguration {

    @Bean(name = "writingEntityManagerFactory")
    public EntityManagerFactory writingEntityManagerFactory() {
        return Persistence.createEntityManagerFactory("persistence.writing");
    }

    @Bean(name = "writingExceptionTranslator")
    public HibernateExceptionTranslator writingHibernateExceptionTranslator() {
        return new HibernateExceptionTranslator();
    }

    @Bean(name = "writingTransactionManager")
    public JpaTransactionManager writingTransactionManager() {
        return new JpaTransactionManager();
    }

}

有时，在我的存储库中，我需要决定是否使用EntityManager:

In my repository I sometimes need to decide with EntityManager to use like so:

@Repository
public class UserReadingRepository {

    @PersistenceContext(unitName = "persistence.reading")
    private EntityManager em;

    // some useful queries here
}

我使用的是我的 persistence.xml 中定义的持久性单元的名称:

I am using persistence unit's name as defined in my persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">

    <persistence-unit name="persistence.reading" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <non-jta-data-source>ReadingDS</non-jta-data-source>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
            <property name="hibernate.show_sql" value="true" />
        </properties>
    </persistence-unit>

    <persistence-unit name="persistence.writing" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <non-jta-data-source>WritingDS</non-jta-data-source>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
            <property name="hibernate.show_sql" value="true" />
        </properties>
    </persistence-unit>

</persistence>

定义了弹簧抛出org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading'.奇怪的是，看起来Spring尝试使用持久性单元名称实例化 bean ?我配置错误了吗?

Spring throws org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading' is defined. Oddly, it looks like Spring tries to instantiate a bean with persistence unit name? Did I misconfigure something?

更新:当我从@PersistenceContext注释中删除unitName = "persistence.reading"时，我将得到以下错误: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [javax.persistence.EntityManagerFactory] is defined: expected single matching bean but found 2: readingEntityManagerFactory,writingEntityManagerFactory

UPDATE: When I remove unitName = "persistence.reading" from @PersistenceContext annotation, I will get following error instead: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [javax.persistence.EntityManagerFactory] is defined: expected single matching bean but found 2: readingEntityManagerFactory,writingEntityManagerFactory

更新2 :Rohit建议(在注释中)连接EntityManagerFactory.因此，我尝试执行以下操作:

UPDATE 2: Rohit suggested (in the comment) to wire EntityManagerFactory instead. So I tried to do the following:

@PersistenceUnit(unitName = "persistence.reading")
private EntityManagerFactory emf;

但Spring仅报告:org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading' is defined

but Spring only reports: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading' is defined

最终修复: 感谢Vlad的回答，我得以更新代码以使用以下代码(只需确保还定义了dataSource bean)即可:

FINAL FIX: Thanks to Vlad's answer, I was able to update the code to use the following (just make sure you define your dataSource bean as well):

@Bean(name = "readingEntityManagerFactory")
public EntityManagerFactory readingEntityManagerFactory() {
    LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
    em.setPersistenceUnitName("persistence.reading");
    em.setDataSource(dataSource());
    em.setPackagesToScan("com.company");
    em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
    em.afterPropertiesSet();
    return em.getObject();
}

推荐答案

EntityManageFactory不是

The EntityManageFactory is not properly configured. You should use a LocalContainerEntityManagerFactoryBean instead:

@Bean(name = "readingEntityManagerFactory")
public EntityManagerFactory readingEntityManagerFactory() {
    LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
    em.setPersistenceUnitName("persistence.reading");
    em.setDataSource(dataSource());
    em.setPackagesToScan("com.company");
    em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
    em.afterPropertiesSet();
    return em.getObject();
}

此外，JpaTransactionManager也配置错误.应该是这样的:

Also the JpaTransactionManager is miss-configured too. It should be something like:

@Bean(name = "readingTransactionManager")
public PlatformTransactionManager readingTransactionManager(){
    JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory(readingEntityManagerFactory());
    return transactionManager;
}

对于读取和写入EntityManager配置，您都需要执行相同的操作.

You need to do the same for both the reading and the writing EntityManager configurations.

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