小编Ale*_*rov的帖子

当我扩展CrudRepository接口时,我的子接口中有exists(ID)方法.我可以写findBy<property>方法.

有可能以某种方式编写existBy<property>将返回的方法boolean.或者用@Query(jpa query)它来注释它将返回boolean.

我知道我可以做select count(*)并返回long,但是我必须!=0检查我的服务层.

我在基于注释的配置类中配置了两个事务管理器：

@Configuration
@EnableTransactionManagement
public class DBConfig implements TransactionManagementConfigurer {

//...

@Override
public PlatformTransactionManager annotationDrivenTransactionManager() {
    return defTransactionManager();
}

@Bean
@Qualifier("defSessionFactory")
public LocalSessionFactoryBean defSessionFactory() {
    LocalSessionFactoryBean sfb = new LocalSessionFactoryBean();
    sfb.setDataSource(defDataSource());

    Properties props = new Properties();
    //...

    sfb.setHibernateProperties(props);
    sfb.setPackagesToScan("my.package");

    return sfb;
}

@Bean
@Qualifier("defTransactionManager")
public PlatformTransactionManager defTransactionManager() {
    return new HibernateTransactionManager(defSessionFactory().getObject());
}

@Bean
@Qualifier("secondSessionFactory")
public LocalSessionFactoryBean secondSessionFactory() {
    LocalSessionFactoryBean sfb = new LocalSessionFactoryBean();
    sfb.setDataSource(secondDataSource());

    Properties props = new Properties();
    //...

    sfb.setHibernateProperties(props);
    sfb.setPackagesToScan("my.package.subpackage");

    return sfb;
}

@Bean
@Qualifier("secondTM")
public PlatformTransactionManager secondTransactionManager() { …