java - 具有一组自身的 Hibernate 映射实体

Question

我的代码中有这个类

@Entity(name = "Point")
@Table(name = "Point")
public class Point extends com.lsikh.unlmaps.base.Entity<Integer>{
    private Integer id;
    ...
    ...
    private Set<Point> connections = new HashSet<Point >();

我需要将 Point 实体与该 Set 中的许多其他 Point 对象相关联并检索。

这是我在数据库中的表

  CREATE
    TABLE Point(
        id INTEGER UNIQUE AUTO_INCREMENT NOT NULL,
        ...
        ...
        PRIMARY KEY (id )
    );

CREATE
    TABLE Connections(
        idA INTEGER NOT NULL,
        idB INTEGER NOT NULL,
        FOREIGN KEY (idA ) REFERENCES Point (id),
        FOREIGN KEY (idB ) REFERENCES Point(id)
    );

这是执行此操作的正确 hibernate 符号集。我觉得可以

@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(name = "Connections", joinColumns = { 
            @JoinColumn(name = "id") }, inverseJoinColumns = { 
                    @JoinColumn(name = "idA") })
    public Set<Point> getConnections() {
        return connections;
    }

但是我在制作 map 时遇到了问题，我不确定。

Answer 1

根据 javadoc，joinColumns:

The foreign key columns of the join table which reference the primary table of the entity owning the association

因此假设 idA 是连接表中拥有实体的 ID，映射应该是:

@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinTable(name = "Connections", joinColumns = { 
        @JoinColumn(name = "idA") }, inverseJoinColumns = { 
                @JoinColumn(name = "idB") })
public Set<Point> getConnections() {
    return connections;
}