配置类中的Spring Boot注入EntityManagerFactory

Question

我正在使用SpringBoot，我想将spring与hibernate集成。我想制作一个会话工厂bean以供进一步使用。但是我不能自动连接EntityManagerFactory，我不能只在configuration类中自动连接它，在其他类中它可以工作。你能帮忙吗？

配置类

package kz.training.springrest.configuration;

@Configuration
@EnableTransactionManagement
public class DatabaseConfiguration {

    @Autowired
    private EntityManagerFactory entityManagerFactory;

    @Bean
    public SessionFactory getSessionFactory() {
        if (entityManagerFactory.unwrap(SessionFactory.class) == null) {
            throw new NullPointerException("factory is not a hibernate factory");
        }
        return entityManagerFactory.unwrap(SessionFactory.class);
    }
}

依赖关系

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.2</version>
        </dependency
    </dependencies>

Answer 1

我不太清楚为什么要公开这两个bean，因为正如@chrylis所指出的，您可以在需要的地方轻松地将EMF展开为SF。

// Some spring component
@Component
public class MyFancyComponent {
  @PersistenceContext
  private EntityManager entityManager;

  public void doSomethingFancy() {
    // public SessionFactory API
    final SessionFactory sf = entityManager
         .unwrap( Session.class ).getFactory();

    // public SessionFactoryImplementor SPI
    final SessionFactoryImplementor sfi = entityManager
         .unwrap( SessionImplementor.class ).getFactory();
  }
}

Answer 2

当你说

但我不能自动连接EntityManagerFactory

它在运行时编译或抛出异常失败吗？如果是后者，堆栈跟踪会说什么？

一种可能的解决方案/解决方法是使用@PersistenceContext注释将em注入配置而不是em工厂：

@Configuration
@EnableTransactionManagement
public class DatabaseConfiguration {

    @PersistenceContext
    private EntityManager entityManager;

    @Bean
    public SessionFactory getSessionFactory() {
        // no need to check for null here because if the unwrap fails, it will do
        // so by throwing a PersistenceException rather than returning null.
        return entityManager.unwrap( Session.class ).getFactory();
    }
}