@Primary 在工厂 Bean 上

Question

我的简化版是这样的：

@Configuration
@EnableTransactionManagement
public class DatabaseDefaultConfig {

  @Bean
  @Primary
  public DataSource dataSourceDefault(DatabaseConfigurationHelper databaseConfigurationHelper) {
    return ...;
  }

  @Bean
  @Primary
  public SqlSessionFactoryBean sqlSessionFactoryBeanDefault(DatabaseConfigurationHelper databaseConfigurationHelper, @Value("${datasource.default.cacheEnabled}") boolean cacheEnabled) throws Exception {
    return ...;
  }

}

@Configuration
@EnableTransactionManagement
public class DatabaseMaintenanceConfig {

  @Bean
  public DataSource dataSourceMaintenance(DatabaseConfigurationHelper databaseConfigurationHelper) {
    return ...;
  }

  @Bean
  public SqlSessionFactoryBean sqlSessionFactoryBeanMaintenance(DatabaseConfigurationHelper databaseConfigurationHelper, @Value("${datasource.maintenance.cacheEnabled}") boolean cacheEnabled) throws Exception {
    return ...;
  }

}

与类大同小异，一个用@Primary。现在让我们创建两个虚拟 bean:

@Configuration
public class CommonDatabaseConfig {

  @Bean
  public AtomicInteger a(SqlSessionFactoryBean sqlSessionFactoryBean) {
    return new AtomicInteger();
  }

  @Bean
  public AtomicLong b(DataSource dataSource) {
    return new AtomicLong();
  }

}

虽然 b 工作正常，但 a 失败并声称找到了两个 bean：

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method a in sjngm.CommonDatabaseConfig required a single bean, but 2 were found:
    - &sqlSessionFactoryBeanDefault: defined by method 'sqlSessionFactoryBeanDefault' in class path resource [sjngm/DatabaseDefaultConfig.class]
    - &sqlSessionFactoryBeanMaintenance: defined by method 'sqlSessionFactoryBeanMaintenance' in class path resource [sjngm/DatabaseMaintenanceConfig.class]


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

请注意，两个 bean 都以 & 开头。阅读 this question 及其答案很明显这是有意的。但是，这似乎打破了 @Primary 的应用，因为它在 Spring 的 DefaultListableBeanFactory:

的这个区域失败了

protected boolean isPrimary(String beanName, Object beanInstance) {
    if (containsBeanDefinition(beanName)) {
        return getMergedLocalBeanDefinition(beanName).isPrimary();
    }
    BeanFactory parent = getParentBeanFactory();
    return (parent instanceof DefaultListableBeanFactory &&
            ((DefaultListableBeanFactory) parent).isPrimary(beanName, beanInstance));
}

containsBeanDefinition() 在第 2 行 returns false 因为 & 符号。

现在：我在这里做错了吗？我该如何解决这个问题？

这是 Spring 4.3.9（作为 Spring-Boot 1.5.4 的一部分）

Answer 1

已在 spring-framework PR 22711.

中修复

@Primary 在工厂 Bean 上

@Primary on Factory Beans

java

spring

factory

dependency-injection