不同的spring bean实例的相同类

Question

I have a Spring application that connects to two databases at the same time. So I have for this two LocalSessionFactoryBean instances for each connection like this:

@Bean
public LocalSessionFactoryBean firstSessionFactory() {
    final LocalSessionFactoryBean lsfb = new LocalSessionFactoryBean();
    lsfb.setPackagesToScan("ro.mycompany.myproject.classes");
    lsfb.setDataSource(dataSourceOne);
    lsfb.setEntityInterceptor(auditInterceptor1);
    lsfb.setHibernateProperties(getHibernateProperties1());
    return lsfb;
}

@Bean
public LocalSessionFactoryBean secondSessionFactory() {
    final LocalSessionFactoryBean lsfb = new LocalSessionFactoryBean();
    lsfb.setPackagesToScan("ro.mycompany.myproject.classes2");
    lsfb.setDataSource(dataSourceTwo);
    lsfb.setEntityInterceptor(auditInterceptor2);
    lsfb.setHibernateProperties(getHibernateProperties2());
    return lsfb;
}

For the DAO layer I have a class that injects the SessionFactory object like this.

public class GenericDAOImpl extends HibernateDAOSupport implements GenericDAO {
     @Autowired 
     private SessionFactory sessionFactory;
     //Other methods goes here
}

I instantiate the beans in my config file like this:

@Bean
public GenericDAO firstGenericDAO() {
    final GenericDAOImpl genericDAO = new GenericDAOImpl();
    return genericDAO;
}

@Bean
public GenericDAO secondGenericDAO() {
    final GenericDAOImpl genericDAO = new GenericDAOImpl();
    return genericDAO;
}

How can I make the firstGenericDAO to use firstSessionFactory and secondGenericDAO to use secondSessionFactory without creating the setters method? I want to use both connection at the same time so also Spring profiles won't help me. Thank you

Answer 1

Either use @Qualifier("...") in addition to @Autowired or just use @Resource(name = "...") . Personally I prefer using @Resource as it replaces the two Annotations with the single one.

In your case, @Resource(name = "firstSessionFactory") and @Resource(name = "secondSessionFactory") respectively.

Answer 2

For you following code,

public class GenericDAOImpl extends HibernateDAOSupport implements GenericDAO {
     @Autowired 
     private SessionFactory sessionFactory;
     //Other methods goes here
}

Spring should be known clearly which bean would be autowired. That means, there should be setter method or some other variable to distinguish your sessionFactory1 and sessionFactory2.

Just as you said, xml-based is still power than annotation. If you don't want to use XML based, and don't want setter method either, I think sessionFactory can be initialized by another variable to identify which bean used.

For example,

public class GenericDAOImpl extends HibernateDAOSupport implements GenericDAO {
    private SessionFactory sessionFactory;

    public GenericDAOImpl(boolean tag) {
        super();
        ApplicationContext apx = new AnnotationConfigApplicationContext(xxxx.class);
        sessionFactory = tag ? (SessionFactory) apx.getBean("sessionFactory1")
                : (SessionFactory) apx.getBean("sessionFactory1");
    }
}

Of course, you need to specify the bean name for LocalSessionFactoryBean with @Bean(name = "sessionFactory1") and @Bean(name = "sessionFactory2")