Query by Spec
介紹與使用 Query by Spec (QBS)
Query by Spec (QBS) 提供了 QueryBySpecExecutor<T> 包含了許多查詢方法:
public interface QueryBySpecExecutor<T> {
List<T> findBySpec(Object spec);
List<T> findBySpec(Object spec, Sort sort);
Page<T> findBySpec(Object spec, Pageable pageable);
// … more functionality omitted.
}
只要在原本的 repository interface 中去繼承 QueryBySpecExecutor<T> 就可以直接使用了:
public interface PersonRepository
extends JpaRepository<Person, Long>, QueryBySpecExecutor<Person> {
...
}
@Service
public class PersonService {
@Autowired PersonRepository personRepository;
public List<Person> findPeople(PersonCriteria criteria) {
return personRepository.findBySpec(criteria);
}
}
Customize Base Repository
在配置的過程中, QBS 會自動配置 Spring Data JPA 的 Base Repository, 預設的實作為 DefaultQueryBySpecExecutor
由於 Java 只能單一繼承, 為了應用程式可以保留原有的 Parent Base Repository, QBS 還多提供了 QueryBySpecExecutorAdapter 擴展點
你的應用程式可以視情況選擇繼承 DefaultQueryBySpecExecutor 或實作 QueryBySpecExecutorAdapter 去客製化 Base Repository, 如:
class MyRepositoryImpl<T, ID> extends SimpleJpaRepository<T, ID>
implements QueryBySpecExecutorAdapter<T> {
@Setter
@Getter
private SpecMapper specMapper;
private final EntityManager entityManager;
MyRepositoryImpl(JpaEntityInformation entityInformation,
EntityManager entityManager) {
super(entityInformation, entityManager);
// Keep the EntityManager around to used from the newly introduced methods.
this.entityManager = entityManager;
}
@Override
public Class<T> getDomainClass() {
return super.getDomainClass();
}
@Transactional
public <S extends T> S mySave(S entity) {
// implementation goes here
}
}
並且透過 properties 中的 spec.mapper.repository-base-class 設定成自定義的 base repository 的 fulll package name, 如:
spec:
mapper:
repository-base-class: com.example.MyRepositoryImpl