如何使用spring JPA在同一事务中维护不同数据库上的多个sql查询

@Configuration
public class DataSourceConfig {
    @Bean
    @ConfigurationProperties(prefix = "datasource.db1")
    public DataSource dataSource1() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties(prefix = "datasource.db2")
    public DataSource dataSource2() {
        return DataSourceBuilder.create().build();
    }
}

@Configuration
@EnableJpaRepositories(
        basePackages = "com.example.repository.db1",
        entityManagerFactoryRef = "entityManagerFactory1",
        transactionManagerRef = "transactionManager1"
)
public class JpaConfig1 {
    @Autowired
    private DataSource dataSource1;

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory1() {
        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource1);
        em.setPackagesToScan("com.example.entity.db1");

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);

        return em;
    }

    @Bean
    public PlatformTransactionManager transactionManager1() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory1().getObject());
        return transactionManager;
    }
}

@Configuration
@EnableJpaRepositories(
        basePackages = "com.example.repository.db2",
        entityManagerFactoryRef = "entityManagerFactory2",
        transactionManagerRef = "transactionManager2"
)
public class JpaConfig2 {
    @Autowired
    private DataSource dataSource2;

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory2() {
        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource2);
        em.setPackagesToScan("com.example.entity.db2");

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);

        return em;
    }

    @Bean
    public PlatformTransactionManager transactionManager2() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory2().getObject());
        return transactionManager;
    }
}

@Repository
public interface UserRepository1 extends JpaRepository<User, Long> {
    // 定义需要的查询方法
}

@Repository
public interface UserRepository2 extends JpaRepository<User, Long> {
    // 定义需要的查询方法
}

@Service
@Transactional
public class UserService {
    @Autowired
    private UserRepository1 userRepository1;

    @Autowired
    private UserRepository2 userRepository2;

    public void performMultipleQueries() {
        // 在同一事务中执行不同数据库的查询操作
        List<User> users1 = userRepository1.findAll();
        List<User> users2 = userRepository2.findAll();

        // 其他业务逻辑处理
    }
}