java - 使用两个事务，一个似乎有效，但另一个无效。为什么？

Question

我在 spring 上处理两个事务，它引用了两个实体管理器，因此引用了两个数据源，同时使用 @Transactional("transaction1") 它工作正常但是 @Transactional("transaction2") 抛出一个错误，指出未找到 Activity 事务。以下是一段代码:

    @Bean(name = "transaction1")
        public PlatformTransactionManager transactionManager() {
            JpaTransactionManager transactionManager = new JpaTransactionManager();
            transactionManager.setEntityManagerFactory(entityManagerFactoryBean2()
                    .getObject());
            return transactionManager;
        }

    @Bean(name = "transaction2")
        public PlatformTransactionManager sermaTransactionManager() {

            JpaTransactionManager transactionManager = new JpaTransactionManager();
            transactionManager
                    .setEntityManagerFactory(entityManagerFactoryBean1()
                            .getObject());

            return transactionManager;
        }

各自的实体经理:

    @Bean(name = "entitymanager1")
        public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean1() {

            LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
            entityManagerFactoryBean.setDataSource(dataSource1());
            entityManagerFactoryBean
                    .setPackagesToScan(new String[] { this.environment
                            .getProperty("db.packagesToScan") });
            entityManagerFactoryBean
                    .setLoadTimeWeaver(new InstrumentationLoadTimeWeaver());
            entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter());

            Map<String, Object> jpaProperties = new HashMap<String, Object>();
            jpaProperties.put("eclipselink.weaving", "false");
            jpaProperties.put("eclipselink.logging.level", "INFO");
            jpaProperties.put("eclipselink.logging.parameters", "true");
            entityManagerFactoryBean.setJpaPropertyMap(jpaProperties);

            return entityManagerFactoryBean;
        }

    @Bean(name = "entitymanager2")
        public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean2() {

            LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
            entityManagerFactoryBean.setDataSource(dataSource2());
            entityManagerFactoryBean
                    .setPackagesToScan(new String[] { this.environment
                            .getProperty("db.packagesToScan") });
            entityManagerFactoryBean
                    .setLoadTimeWeaver(new InstrumentationLoadTimeWeaver());
            entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter());

            Map<String, Object> jpaProperties = new HashMap<String, Object>();
            jpaProperties.put("eclipselink.weaving", "false");
            jpaProperties.put("eclipselink.logging.parameters", "true");
            jpaProperties.put("eclipselink.logging.level", "INFO");
            entityManagerFactoryBean.setJpaPropertyMap(jpaProperties);

            return entityManagerFactoryBean;
        }

各自的数据源:

@Bean("datasource1")
public DriverManagerDataSource dataSource1() {

        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource                        .setDriverClassName(this.environment.getProperty("db.driver"));
        dataSource.setUrl(this.environment.getProperty("db.url"));
        dataSource.setUsername(this.environment
                .getProperty("db.username.abc"));
        dataSource.setPassword(this.environment
                .getProperty("db.password.abc"));

        return dataSource;
    }
@Bean("datasource2")
public DriverManagerDataSource dataSource2() {

        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource
                .setDriverClassName(this.environment.getProperty("db.driver"));
        dataSource.setUrl(this.environment.getProperty("db.url"));
        dataSource.setUsername(this.environment.getProperty("db.username"));
        dataSource.setPassword(this.environment.getProperty("db.password"));

        return dataSource;
    }

我的 genericDaoImpl 具有以下链接各个实体管理器的内容:

@PersistenceContext(unitName = "entitymanager1")
    private EntityManager em1;

    @PersistenceContext(unitName = "entitymanager2")
    private EntityManager em2;

当我执行@Transactional("transaction1") 时它工作正常，但是当我执行@Transactional("transaction2") 时它说没有 Activity 事务。当我没有提到交易的限定符时，错误说找到了两个交易(交易 1、交易 2)。任何帮助都会很棒。

Answer 1

配置有问题:

问题是当 bean 像这样初始化时:

transactionManager.setEntityManagerFactory(entityManagerFactoryBean2().getObject());

调用entityManagerFactoryBean2()会创建一个新的实体管理器工厂，然后@Bean注解会触发另一个实体管理器工厂的创建，与配置。

当您在 bean 中注入(inject)带有 @Autowired 的实体管理器工厂时，您注入(inject)的是用 @Bean 创建的实例，不是传递给事务管理器的实例.

一个关于配置的警告:

上面的配置允许在两个单独的数据源中进行事务处理，但是使用此配置不可能进行跨越两个 数据库的事务处理。例如:

@Service
public class PlanesService {

    @PersistenceContext(unitName = "entityManagerFactory1")
    private EntityManager em1;

    @PersistenceContext(unitName = "entityManagerFactory2")
    private EntityManager em2;


    @Transactional("transactionManager1")
    public Plane savePlanes() {
        F14 f14 = new F14("F14","f14");
        F16 f16 = new F16("F16","f16");

        em1.persist(f14);
        em2.persist(f16);

        return f14;
    }
}

此代码将仅保留 f14，因为唯一具有正在进行的事务的实体管理器是 em1(由于 @Transactional("transactionManager1"))。对 em2.persist() 的调用将被忽略(尽管 em2 仍然可以读取)。

如果您想执行包含两个数据库的事务，您需要一个 JTA 事务管理器。

工作配置示例:

这是修复上述注入(inject)问题的配置示例:

@Configuration
public class DataSourcesConfig {

    @Bean(name = "datasource1")
    public DriverManagerDataSource dataSource1() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        ...
        return dataSource;
    }

    @Bean(name = "datasource2")
    public DriverManagerDataSource dataSource2() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        ...
        return dataSource;
    }
}

@Configuration
public class EntityManagerFactoriesConfiguration {

    @Autowired
    @Qualifier("datasource1")
    private DataSource dataSource1;

    @Autowired
    @Qualifier("datasource2")
    private DataSource dataSource2;


    @Bean(name = "entityManagerFactory1")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {

        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource1);
        entityManagerFactoryBean.setPackagesToScan(new String[] { "your.package.here" });
        entityManagerFactoryBean.setLoadTimeWeaver(new InstrumentationLoadTimeWeaver());
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());

        Map<String, Object> jpaProperties = new HashMap<String, Object>();
        ...
        entityManagerFactoryBean.setJpaPropertyMap(jpaProperties);

        return entityManagerFactoryBean;
    }

    @Bean(name = "entityManagerFactory2")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean2() {

        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource2);
        entityManagerFactoryBean.setPackagesToScan(new String[] { "your.package.here" });
        entityManagerFactoryBean.setLoadTimeWeaver(new InstrumentationLoadTimeWeaver());
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());

        Map<String, Object> jpaProperties = new HashMap<String, Object>();

        entityManagerFactoryBean.setJpaPropertyMap(jpaProperties);
        ...
        return entityManagerFactoryBean;
    }
}     


@Configuration
@EnableTransactionManagement
public class TransactionManagersConfig {

    @Autowired
    @Qualifier("entityManagerFactory1")
    EntityManagerFactory entityManagerFactory1;

    @Autowired
    @Qualifier("entityManagerFactory2")
    EntityManagerFactory entityManagerFactory2;

    @Autowired
    @Qualifier("datasource1")
    private DataSource dataSource1;

    @Autowired
    @Qualifier("datasource2")
    private DataSource dataSource2;

    @Bean(name = "transactionManager1")
    public PlatformTransactionManager transactionManager1() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory1);
        transactionManager.setDataSource(dataSource1);
        return transactionManager;
    }

    @Bean(name = "transactionManager2")
    public PlatformTransactionManager transactionManager2() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory2);
        transactionManager.setDataSource(dataSource2);
        return transactionManager;
    }
}

通过将配置拆分为多个 @Configuration 类并 Autowiring 它们，我们确保始终使用相同的 beans(单例)。

注意启用@Transactional 的@EnableTransactionManagement 注释。