Spring JPA 和 LazyInitializationException

Question

我正在使用 spring-jpa。我有 2 个测试。

@Test
@Transactional
public void testFindAll() {
    List<Engine> eList = engineService.findAll();
    Engine e = eList.get(0); //this engine id=3
    List<Translation> tList = e.getTranslations();
    for(Translation t : tList) {
        ...
    }
}

此方法因以下异常而失败：

org.hibernate.LazyInitializationException: 延迟初始化失败 角色集合：xxx.Engine.translations，无法初始化 代理 - 没有会话

但是，这种方法效果很好：

@Test
@Transactional
public void testFindOne() {
    Engine e = engineService.findOne(3);
    List<Translation> tList = e.getTranslations();
    for(Translation t : tList) {
        ...
    }
}

为什么翻译列表在一种情况下加载成功，而在另一种情况下却没有？

编辑：服务/回购代码：

public interface EngineRepository extends JpaRepository<Engine, Integer>
{   
}

.

@Service
@Transactional
public class EngineService
{
    @Autowired
    private EngineRepository engineRepository;

    public List<Engine> findAll()
    {
        return engineRepository.findAll();
    }

    public Engine findOne(Integer engId)
    {
        return engineRepository.findOne(engId);
    }
}

.

public class Engine implements Serializable {
    ...
    @OneToMany
    @JoinColumn(name="ID", referencedColumnName="TRAN_ID",  insertable=false, updatable=false, nullable=true)
    @LazyCollection(LazyCollectionOption.EXTRA)
    private List<Translation> translations;
    ...
}

配置：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"xxx.dao"})
@ComponentScan(basePackages = {"xxx.dao", "xxx.service", "xxx.bean"})
@PropertySource("classpath:application.properties")
public class SpringDataConfig {

  @Autowired
  private Environment environment;

  @Bean
  public DataSource dataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setUrl(environment.getProperty("db.url"));
    dataSource.setDriverClassName(environment.getProperty("db.driverClass"));
    dataSource.setUsername(environment.getProperty("db.username"));
    dataSource.setPassword(environment.getProperty("db.password"));
    return dataSource;
  }

  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory() throws NamingException {
    HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
    hibernateJpaVendorAdapter.setDatabase(Database.POSTGRESQL);

    Properties properties = new Properties();


    properties.put("hibernate.dialect", environment.getProperty("hibernate.dialect"));
    properties.put("hibernate.show_sql", environment.getProperty("hibernate.showSQL"));
    properties.put("hibernate.format_sql", environment.getProperty("hibernate.formatSQL"));

    LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
    entityManagerFactoryBean.setDataSource(dataSource());
    entityManagerFactoryBean.setPackagesToScan("xxx.model");
    entityManagerFactoryBean.setJpaVendorAdapter(hibernateJpaVendorAdapter);
    entityManagerFactoryBean.setJpaProperties(properties);

    return entityManagerFactoryBean;
  }

  @Bean
  public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
    JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory(entityManagerFactory);

    return transactionManager;
  }
}

Answer 1

我认为这里的问题是会话在第一种情况下的第一行之后关闭。您应该查看 findAll() 的 JpaRepository 实现。

Answer 2

使用 Spring 进行集成测试

您似乎未能在您的 TestCase 中提供 Spring 上下文，这意味着什么？ @Transactional 被忽略。因此，您最终会遇到关闭会话异常，因为没有事务。

看看如何使用 Spring Context here 配置 TestCase

@RunWith(SpringJUnit4ClassRunner.class)
// ApplicationContext will be loaded from AppConfig and TestConfig
@ContextConfiguration(classes = {AppConfig.class, TestConfig.class})
public class MyTest {

     @Autowired
     EngineService engineService;

     @Test
     @Transactional
     public void testFindOne() {}

     @Test
     @Transactional
     public void testFindAll() {}

}