Spring-Boot：如何限制Beans的可见性

Question

I have two custom PlatformTransactionManager beans injected into the Spring framework with specific names as follows:

@Bean(name = "ubldbTransactionManager")
protected PlatformTransactionManager transactionManager(
        @Qualifier("ubldbEntityManagerFactory") EntityManagerFactory entityManagerFactory) {
    return new JpaTransactionManager(entityManagerFactory);
}

@Bean(name = "bpdbTransactionManager")
public PlatformTransactionManager bpdbTransactionManager(
        @Qualifier("bpdbEntityManagerFactory") EntityManagerFactory entityManagerFactory) {
    return new JpaTransactionManager(entityManagerFactory);
}

A 3rd-party library has a @Autowired protected PlatformTransactionManager transactionManager; dependency. So, the 3rd party library is not supposed to use none of the two TransactionManagers . However, as you see there is no Qualifier for the dependency injection in the external library and I get an error as follows:

Field transactionManager in org.camunda.bpm.spring.boot.starter.configuration.impl.DefaultDatasourceConfiguration required a single bean, but 2 were found:
    - bpdbTransactionManager: defined by method 'bpdbTransactionManager' in class path resource [eu/nimble/service/bp/config/BusinessProcessDBConfig.class]
    - ubldbTransactionManager: defined by method 'transactionManager' in class path resource [eu/nimble/service/bp/config/UBLDBConfig.class]

So, how can I restrict the visibility of the two Beans so that they would not be accessible by the 3rd-party library?

Answer 1

DefaultDatasourceConfiguration is provided to use default Spring beans eg DataSource named dataSource and PlatformTransactionManager named transcationManager . It's there to glue Camunda into a Spring Boot application which be default has a single data source.

Since you have created your own PlatformTransactionManager beans this disabled Spring Boot's default transaction manager bean named transcationManager (as per TransactionAutoConfiguration Spring Boot auto-configuration logic).

You most likely need to define one more transactionManager (and potentially dataSource ) for Camunda's process engine, which requires it's own schema. Make sure to use the right bean name as below:

@Bean
public PlatformTransactionManager transactionManager() {
  ...
}

Starting from Spring 4 the bean name is the default qualifier when auto-wiring so the new transaction manager will be wired into DefaultDatasourceConfiguration as it matches the field name in the class.

Alternatively don't use DefaultDatasourceConfiguration and roll out your own configuration if Spring Boot defaults are not working for you.

Answer 2

Use @Qualifier annotation The @Qualifier annotation is used to resolve the autowiring conflict, when there are multiple beans of same type.

@Bean
@Qualifier("ubldbTransactionManager")
protected PlatformTransactionManager transactionManager

and

@Bean
@Qualifier("bpdbTransactionManager")
public PlatformTransactionManager bpdbTransactionManager