[英]How to implement Generic JPA Repository in Spring Boot - Which can be autowired into spring services for any entity/class type
这是扩展 spring PagingAndSortingRepository 的示例通用存储库实现,
@NoRepositoryBean
public interface GenericRepository<T, ID extends Serializable> extends PagingAndSortingRepository<T, ID> {
public List<T> findByNamedQuery( String name );
public List<T> findByNamedQueryAndParams( String name, Map<String, Object> params );
public T findOneByNamedQuery( String name );
public T findOneByNamedQueryAndParams( String name, Map<String, Object> params );
}
工厂 Bean 类,
public class GenericRepositoryFactoryBean<R extends JpaRepository<T, I>, T, I extends Serializable> extends
JpaRepositoryFactoryBean<R, T, I> {
@SuppressWarnings( "rawtypes" )
protected RepositoryFactorySupport createRepositoryFactory( EntityManager em )
{
return new MyRepositoryFactory(em);
}
private static class MyRepositoryFactory<T, I extends Serializable> extends JpaRepositoryFactory {
private final EntityManager em;
public MyRepositoryFactory( EntityManager em )
{
super(em);
this.em = em;
}
@SuppressWarnings( "unchecked" )
protected Object getTargetRepository( RepositoryMetadata metadata )
{
return new GenericRepositoryImpl<T, I>((Class<T>) metadata.getDomainType(), em);
}
protected Class<?> getRepositoryBaseClass( RepositoryMetadata metadata )
{
return GenericRepositoryImpl.class;
}
}
}
实现类,
public final class GenericRepositoryImpl<T, ID extends Serializable> extends SimpleJpaRepository<T, ID> implements
GenericRepository<T, ID> {
private final EntityManager em;
private final Class<T> domainClass;
public GenericRepositoryImpl( Class<T> domainClass, EntityManager entityManager )
{
super(domainClass, entityManager);
this.em = entityManager;
this.domainClass = domainClass;
}
@Override
public List<T> findByNamedQuery( final String name )
{
validate(name);
return this.em.createNamedQuery(name, domainClass).getResultList();
}
@Override
public T findOneByNamedQuery( String name )
{
validate(name);
return this.em.createNamedQuery(name, domainClass).getSingleResult();
}
@Override
public List<T> findByNamedQueryAndParams( String name, Map<String, Object> params )
{
validate(name, params);
final TypedQuery<T> query = this.em.createQuery(name, domainClass);
setParams(query, params);
return query.getResultList();
}
}
因此,当我尝试将 GenericRepository 自动装配到不同类型(如 Customer.java、Message.java 等)的服务中时,它抛出需要至少一种 bean 类型的接口 GenericRepository。 如果当我为客户和消息类型创建单独的存储库时,这会起作用。 如果不创建多个存储库,我将无法实现这一点。
@Service
@Transactional( noRollbackFor = Exception.class )
public class CustomerService {
@Autowired
private GenericRepository<Customer, Serializable> cr; works fine with just one entity type
@Autowired
private GenericRepository<Message, Serializable> cr; throws exception
如果有 100 个或更多实体类,那么我最终会创建 100 个存储库,这很糟糕。 请让我知道是否有更好的方法来做到这一点。
对于我读过的内容,通过@Query 注释告诉新的接口方法要做什么会更容易,并且不要用 BeanFactory 或 impl ...
@Repository
public interface GenericRepository<T, ID extends Serializable> extends JpaRepository<T, ID> {
@Query(value = "SELECT c FROM customers c WHERE c.name = :name")
public List<T> findByNamedQuery( String name );
...
}
如果这对您不适用,并且您说您的代码适用于一个存储库但在您添加第二个时失败,我的第一个想法是尝试将 bean 的范围设置为原型,但这只是一种推测。 如果我真的没有帮助,我很抱歉,不要太讨厌我^^
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