java - 非必需的 1 到 1 映射的 Hibernate 投影/延迟加载

Question

我有以下 2 个类(针对这篇文章进行了缩减)

public class ApplicationVO implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = -3314933694797958587L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    private Integer id;


    @OneToOne(fetch = FetchType.LAZY, mappedBy = "application")
    @Cascade({ CascadeType.ALL })
    @JsonIgnore
    private ApplicationHomeScreenVO applicationHomeScreen;

...
...
... 
}


public class ApplicationHomeScreenVO implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = -9158898930601867545L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    @JsonProperty("id")
    private Integer id;

    @OneToOne(fetch = FetchType.LAZY)
    @Cascade({ CascadeType.SAVE_UPDATE })
    @JoinColumn(name="application_id")
    @JsonProperty("application")
    protected ApplicationVO application;    

    ...
    ...
    ...
}

我试图在不加载 applicationHomeScreen 的情况下加载 applicationById不幸的是，延迟加载似乎不起作用。我看过其他帖子，他们建议在 @OneToOne 注释上设置 option=false 标志，但不幸的是，applicationHomeScreen 可以是可选的

我现在正在尝试使用投影，但这对我也不起作用

当我调用下面的方法时

 public ApplicationVO findApplicationById(Integer applicationId) {

        Criteria criteria = currentSession().createCriteria(ApplicationVO.class);
        criteria.add(Restrictions.eq("id", applicationId));

        criteria.setProjection(Projections.projectionList()
                .add(Projections.property("applicationHomeScreen"), "applicationHomeScreen"))
              .setResultTransformer(Transformers.aliasToBean(ApplicationVO.class));

        ApplicationVO applicationVO = (ApplicationVO) criteria.uniqueResult();

        return applicationVO;
    }

我得到堆栈跟踪

java.lang.ArrayIndexOutOfBoundsException: 0
    at org.hibernate.loader.criteria.CriteriaLoader.getResultRow(CriteriaLoader.java:168)
    at org.hibernate.loader.criteria.CriteriaLoader.getResultColumnOrRow(CriteriaLoader.java:148)
    at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:754)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:953)
    at org.hibernate.loader.Loader.doQuery(Loader.java:921)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:355)
    at org.hibernate.loader.Loader.doList(Loader.java:2554)
    at org.hibernate.loader.Loader.doList(Loader.java:2540)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2370)
    at org.hibernate.loader.Loader.list(Loader.java:2365)
    at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:126)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1682)
    at org.hibernate.internal.CriteriaImpl.list(CriteriaImpl.java:380)
    at org.hibernate.internal.CriteriaImpl.uniqueResult(CriteriaImpl.java:402)
    at com.dao.database.impl.ApplicationDAOImpl.findApplicationById(ApplicationDAOImpl.java:349)

任何人都可以推荐一种我可以使用的方法吗a)在不需要关联的一对一映射中使延迟加载正常工作b) 让预测工作，这样我就不需要加载任何不需要的子关联

谢谢达米安

Answer 1

唯一的选择是遵循以下步骤:

1. 添加@LazyToOne到一对一关联:

   @OneToOne(fetch = FetchType.LAZY, mappedBy = "application")
   @Cascade({ CascadeType.ALL })
   @JsonIgnore
   @LazyToOne(value = LazyToOneOption.NO_PROXY)
   private ApplicationHomeScreenVO applicationHomeScreen;
   

2. 配置bytecode enhancement