HIbernate

Question

如果我的项目中有以下classes

    @Entity
@Table(name = "application_home_screen")
public class ApplicationHomeScreenVO implements Serializable {

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

    @OneToOne(fetch = FetchType.EAGER)
    @Cascade({ CascadeType.ALL })
    @JoinColumn(name="image1_id")
    private ApplicationImageVO image1;

    @OneToOne(fetch = FetchType.EAGER)
    @Cascade({ CascadeType.ALL })
    @JoinColumn(name="image2_id")
    private ApplicationImageVO image2;  
}



@Entity
@Table(name = "application_image")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class ApplicationImageVO implements Serializable {

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


    @OneToOne(fetch = FetchType.LAZY, mappedBy = "image1")
    @Cascade({ CascadeType.ALL })
    private ApplicationHomeScreenVO homeScreenImage1;   

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "image2")
    @Cascade({ CascadeType.ALL })
    private ApplicationHomeScreenVO homeScreenImage2;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity1")
    @Cascade({ CascadeType.ALL })
    private OtherEntity1 otherEntity1;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity2")
    @Cascade({ CascadeType.ALL })
    private OtherEntity2 otherEntity2;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity3")
    @Cascade({ CascadeType.ALL })
    private OtherEntity3 otherEntity3;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity4")
    @Cascade({ CascadeType.ALL })
    private OtherEntity4 otherEntity3;
}

当我加载 ApplicationHomeVO 时 - id 只希望从 ApplicationImageVO 加载 image1 和 image2 class 但事实并非如此

ApplicationImageVO class 中的所有其他对象也会被加载，即使它们被标记为 LAZY。我希望只加载 ApplicationHomeScreenVO 对象

有什么方法可以阻止加载这些其他实体吗？

谢谢大米

Answer 1

@OneToOne这种方式声明的是PK映射的，必须急切获取...

你可以:

让它成为 @ManyToOne(fetch=FetchType.LAZY)

或

声明一个外键列：

@OneToOne(fetch = FetchType.LAZY) @JoinColumn(name="fk") public T getT()

编辑

@Entity
@Table(name = "application_home_screen")
public class ApplicationHomeScreenVO implements Serializable {

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

    @OneToOne(fetch = FetchType.EAGER)
    @Cascade({ CascadeType.ALL })
    @JoinColumn(name="image1_id")
    private ApplicationImageVO image1;

    @OneToOne(fetch = FetchType.EAGER)
    @Cascade({ CascadeType.ALL })
    @JoinColumn(name="image2_id")
    private ApplicationImageVO image2;  
}



@Entity
@Table(name = "application_image")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class ApplicationImageVO implements Serializable {

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


    @OneToOne(fetch = FetchType.LAZY, mappedBy = "image1")
    @Cascade({ CascadeType.ALL })
    private ApplicationHomeScreenVO homeScreenImage1;   

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "image2")
    @Cascade({ CascadeType.ALL })
    private ApplicationHomeScreenVO homeScreenImage2;

    @ManyToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity1")
    @Cascade({ CascadeType.ALL })
    private OtherEntity1 otherEntity1;

    @ManyToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity2")
    @Cascade({ CascadeType.ALL })
    private OtherEntity2 otherEntity2;

    @ManyToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity3")
    @Cascade({ CascadeType.ALL })
    private OtherEntity3 otherEntity3;

    @ManyToOne(fetch = FetchType.LAZY, mappedBy = "otherEntity4")
    @Cascade({ CascadeType.ALL })
    private OtherEntity4 otherEntity3;
}

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