spring-data-jpa中标准的等价物

Question

我一直在使用hibernate，但我听说spring-data-jpa是最好的，所以我尝试了一下，我对它很满意，直到我遇到这个问题。

我的jsp中有一个带有许多条件的搜索表单，用户可以选择他想要的任何内容。

那么在spring-data-jpa中这个请求的等价物是什么呢？

if(startDate!=null){
    criteria.add(Expression.ge("date",startDate));
}
if(endDate!=null){
    criteria.add(Expression.le("date",endDate));
}
if(volume!=null){
    criteria.add(Expression.ge("volume",volume));
}
if ....

Answer 1

我是QueryDSL。在Here's上发表一篇博文，介绍如何在Spring Data中使用它。

Answer 2

Spring Jpa数据中的等价物是Specification，您可以使用存储库SpecificationExecutor<T>和Jpa MetaModel来创建您的Jpa标准。

您可以找到关于Jpa JpaSpecificationExecutor的介绍。

一个简单的例子：

1. Entity

@Entity

public class ClassRoom {
    // id and other properties

    @ManyToOne
    private School school;

    private Date creationDate;

    private String reference;
    // Getters and setters
}

2.存储库：

    @Repository
public interface ClassRoomRepository extends JpaSpecificationExecutor<ClassRoom>{
}

2.服务接口：

public interface ClassRoomService {

List<ClassRoom> list(String reference, String schoolName,
        Date creationDate)
}

3.服务实现：

import static yourpackage.ClassRoomSpecifications.*;
import static org.springframework.data.jpa.domain.Specifications.*;
@Service
public class ClassRoomServiceImpl implements ClassRoomService {

    @Resource
    private ClassRoomRepository repository;


    @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public List<ClassRoom> list(String reference, String schoolName,
            Date creationDate) {

        Specifications<ClassRoom> spec = null;
        Specifications<ClassRoom> tempo = null;

        spec = where(findPerSchool(schoolName));

        if (reference != null) {
            tempo = where(findPerReference(reference));
        }

        if (creationDate!=null) {
            tempo = tempo == null ? where(findPerCreationDate(creationDate):tempo.and(findPerCreationDate(creationDate));
        }
        spec = tempo == null ? spec : spec.and(tempo);
        return repository.findAll(spec);
    }
}

Answer 3

对于Spring data，您只需使用存储库。

   And  findByLastnameAndFirstname  … where x.lastname = ?1 and x.firstname = ?2
   Or   findByLastnameOrFirstname   … where x.lastname = ?1 or x.firstname = ?2
   Between  findByStartDateBetween  … where x.startDate between 1? and ?2
   LessThan findByAgeLessThan   … where x.age < ?1
   GreaterThan  findByAgeGreaterThan    … where x.age > ?1
   IsNull   findByAgeIsNull … where x.age is null
   IsNotNull,NotNull    findByAge(Is)NotNull    … where x.age not null
   Like findByFirstnameLike … where x.firstname like ?1
   NotLike  findByFirstnameNotLike  … where x.firstname not like ?1
   OrderBy  findByAgeOrderByLastnameDesc    … where x.age > ?1 order by x.lastname desc
   Not  findByLastnameNot   … where x.lastname <> ?1