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[英]What is the best approach to reuse similar method in multiple Services that use similar objects?
[英]What is the best approach to reuse multiple repository criterias?
我有一個存儲庫層,它具有許多方法組合,以匹配搜索條件。.重用此條件的最佳方法是什么? 我認為像findByNameAndIdAndBirthdayAndAccounaNumber這樣的方法名稱不是一個好主意! 謝謝 !
public Order findByIdAndName(String orderId) {
List<OrderEntity> list = entityManager.createNamedQuery(OrderEntity.QUERY_FIND_BY_ORDERID_AND_NAME, OrderEntity.class)
.setParameter("orderId", orderId)
.setParameter("name", name).getResultList();
if (list.isEmpty()) {
return null;
}
OrderEntity orderEntity = list.get(0);
return toOrder(orderEntity);
}
聽起來您可能正在尋找“規范”模式,這將使您可以編寫如下方法:
public Order findOrderBySpecification(Specification specification) {
}
然后結合使用一種或多種規范(例如,按帳號,按帳號和名稱等)進行調用。
這里有一個使用Criteria API的示例:
http://java.dzone.com/articles/java-using-specification
另請參見下面的文章,該文章引用了Spring Data項目,但是即使您沒有使用Spring,也仍然值得一讀。
http://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/
另外,您可以使用上一篇文章中引用的QueryDSL庫來更簡單地實現此目的,而不是使用Straight JPA(即不使用Spring)的冗長的Criteria API。
http://blog.mysema.com/2010/04/querydsl-as-alternative-to-jpa-2.html http://www.querydsl.com/static/querydsl/2.1.0/reference/html/ch02s02 html的
嘗試在存儲庫實現中使用規范模式。
OrderSpecificationByName.java
public class OrderSpecificationByName implements OrderSpecification, HibernateSpecification {
private String name;
public OrderSpecificationByName(String name) {
super();
this.name = name;
}
@Override
public boolean isSatisfiedBy(Object order) {
return ((Order)order).hasName(name);
}
@Override
public Criterion toCriteria() {
return Restrictions.eq("name", name);
}
}
OrderSpecificationById.java
public class OrderSpecificationById implements OrderSpecification, HibernateSpecification {
private Long id;
public OrderSpecificationById(String id) {
super();
this.id = id;
}
@Override
public boolean isSatisfiedBy(Object order) {
return ((Order)order).hasId(id);
}
@Override
public Criterion toCriteria() {
return Restrictions.eq("id", id);
}
}
然后,您必須實施邏輯規范AndSpecification
, OrSpecification
, NotSpecification
等。
AndSpecification.java
public class AndSpecification implements HibernateSpecification {
private Specification first;
private Specification second;
public AndSpecification(Specification first, Specification second) {
first = first;
second = second;
}
@Override
public boolean isSatisfiedBy(Object candidate) {
return first.isSatisfiedBy(candidate) && second.isSatisfiedBy(candidate);
}
@Override
public Criterion toCriteria() {
Conjunction conjuntion = Restrictions.conjunction();
conjuntion.add(first.toCriteria());
conjuntion.add(second.toCriteria());
return conjuntion;
}
}
OrderRepository.java
public List<Order> query(HibernateSpecification specification) {
Session session = sessionFactory.getCurrentSession();
Criteria criteria = session.createCriteria(Order.class);
criteria(specification.toCriteria());
return criteria.list();
}
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