Spring Boot 中针对不同 EntityManager 的多个事务管理器

使用Spring Boot开发应用程序时，我们通常会涉及到多个数据源和多个EntityManager，而每个数据源可能需要使用不同的事务管理器来管理事务。Spring Boot提供了灵活的配置选项，可以轻松地为不同的EntityManager配置不同的事务管理器。

properties
# 数据源1
spring.datasource.url=db1.url
spring.datasource.username=db1.username
spring.datasource.password=db1.password
# 数据源2
spring.datasource.second.url=db2.url
spring.datasource.second.username=db2.username
spring.datasource.second.password=db2.password

java
@Configuration
@EnableTransactionManagement
public class JpaConfig {
    @Primary
    @Bean(name = "entityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            EntityManagerFactoryBuilder builder,
            @Qualifier("dataSource") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.entity")
                .build();
    }
    @Bean(name = "secondEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean secondEntityManagerFactory(
            EntityManagerFactoryBuilder builder,
            @Qualifier("secondDataSource") DataSource secondDataSource) {
        return builder
                .dataSource(secondDataSource)
                .packages("com.example.entity")
                .build();
    }
    @Primary
    @Bean(name = "transactionManager")
    public PlatformTransactionManager transactionManager(
            @Qualifier("entityManagerFactory") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
    @Bean(name = "secondTransactionManager")
    public PlatformTransactionManager secondTransactionManager(
            @Qualifier("secondEntityManagerFactory") EntityManagerFactory secondEntityManagerFactory) {
        return new JpaTransactionManager(secondEntityManagerFactory);
    }
}

java
@Service
public class UserService {
    @Autowired
    private EntityManager entityManager;
    @Autowired
    @Qualifier("secondTransactionManager")
    private PlatformTransactionManager secondTransactionManager;
    @Transactional
    public void saveUser(User user) {
        entityManager.persist(user);
    }
    @Transactional("secondTransactionManager")
    public void saveUserInSecondDataSource(User user) {
        entityManager.persist(user);
    }
}