使用Hibernate:

@Transactional(readOnly=true)
public void accessUser() {
    EntityManager em = repo.getEntityManager();
    org.hibernate.Session session = em.unwrap(org.hibernate.Session.class);
    org.hibernate.SQLQuery q = (org.hibernate.SQLQuery) session.createSQLQuery("SELECT u.username, u.name, u.email, 'blabla' as passe, login_type as loginType FROM users u")
        .addScalar("username", StringType.INSTANCE).addScalar("name", StringType.INSTANCE)
        .addScalar("email", StringType.INSTANCE).addScalar("passe", StringType.INSTANCE)
        .addScalar("loginType", IntegerType.INSTANCE)
        .setResultTransformer(Transformers.aliasToBean(User2DTO.class));

    List<User2DTO> userList = q.list();
}

使用DTO设计模式。它在EJB 2.0中使用。实体由容器管理。采用DTO设计模式来解决这一问题。 但是，当应用程序分别开发服务器端和客户端时，现在可能会使用它。DTO用于服务器端不想将带有注释的实体传递/返回给客户端。

DTO示例:

PersonEntity.java

@Entity
public class PersonEntity {
    @Id
    private String id;
    private String address;

    public PersonEntity(){

    }
    public PersonEntity(String id, String address) {
        this.id = id;
        this.address = address;
    }
    //getter and setter

}

PersonDTO.java

public class PersonDTO {
    private String id;
    private String address;

    public PersonDTO() {
    }
    public PersonDTO(String id, String address) {
        this.id = id;
        this.address = address;
    }

    //getter and setter 
}

DTOBuilder.java

public class DTOBuilder() {
    public static PersonDTO buildPersonDTO(PersonEntity person) {
        return new PersonDTO(person.getId(). person.getAddress());
    }
}

java <——可能需要

public class EntityBuilder() {
    public static PersonEntity buildPersonEntity(PersonDTO person) {
        return new PersonEntity(person.getId(). person.getAddress());
    }
}

使用Hibernate:

@Transactional(readOnly=true)
public void accessUser() {
EntityManager em = repo.getEntityManager();
    org.hibernate.Session session = em.unwrap(org.hibernate.Session.class);
    org.hibernate.SQLQuery q = (org.hibernate.SQLQuery) session.createSQLQuery("SELECT u.username, u.name, u.email, 'blabla' as passe, login_type as loginType FROM users u").addScalar("username", StringType.INSTANCE).addScalar("name", StringType.INSTANCE).addScalar("email", StringType.INSTANCE).addScalar("passe", StringType.INSTANCE).addScalar("loginType", IntegerType.INSTANCE)
        .setResultTransformer(Transformers.aliasToBean(User2DTO.class));

    List<User2DTO> userList = q.list();
}

可以执行展开过程，将结果分配给非实体(即Beans/POJO)。操作步骤如下。

List<JobDTO> dtoList = entityManager.createNativeQuery(sql)
        .setParameter("userId", userId)
        .unwrap(org.hibernate.Query.class).setResultTransformer(Transformers.aliasToBean(JobDTO.class)).list();

该用法用于JPA-Hibernate实现。

是的，使用JPA 2.1很容易。你有非常有用的注解。他们简化了你的生活。

首先声明本机查询，然后声明结果集映射(它定义了数据库返回的数据到pojo的映射)。编写要引用的POJO类(为了简洁，这里没有包括)。最后但同样重要的是:在DAO中创建一个方法(例如)来调用查询。这在dropwizard(1.0.0)应用中很管用。

首先在实体类中声明一个本机查询:

@NamedNativeQuery (
name = "domain.io.MyClass.myQuery",
query = "Select a.colA, a.colB from Table a",
resultSetMapping = "mappinMyNativeQuery")   // must be the same name as in the SqlResultSetMapping declaration

下面你可以添加resultset映射声明:

@SqlResultSetMapping(
name = "mapppinNativeQuery",  // same as resultSetMapping above in NativeQuery
   classes = {
      @ConstructorResult( 
          targetClass = domain.io.MyMapping.class,
          columns = {
               @ColumnResult( name = "colA", type = Long.class),  
               @ColumnResult( name = "colB", type = String.class)
          }
      )
   } 
)

稍后在DAO中，您可以将查询引用为

public List<domain.io.MyMapping> findAll() {
        return (namedQuery("domain.io.MyClass.myQuery").list());
    }

就是这样。

在hibernate中，您可以使用此代码轻松映射本机查询。

private List < Map < String, Object >> getNativeQueryResultInMap() {
String mapQueryStr = "SELECT * FROM AB_SERVICE three ";
Query query = em.createNativeQuery(mapQueryStr);
NativeQueryImpl nativeQuery = (NativeQueryImpl) query;
nativeQuery.setResultTransformer(AliasToEntityMapResultTransformer.INSTANCE);
List < Map < String, Object >> result = query.getResultList();
for (Map map: result) {
    System.out.println("after request  ::: " + map);
}
return result;}