java - Hibernate 在 @JoinTable 上创建关系

Question

我有两个具有多对多关系的表，它们具有如下的 JoinTable USER_SERVICES。

@Entity
public class User implements Serializable {

    @NotNull
    @Column(unique=true)
    private String username;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(
            name = "USER_SERVICES",
            joinColumns = {@JoinColumn(name = "id", referencedColumnName = "id")},
            inverseJoinColumns = {@JoinColumn(name = "", referencedColumnName = "name")})
    private Set<Services> services;

    // Getters and Setters
}   


@Entity
public class Services implements Serializable {

    @NotNull
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Id
    private Long serviceId;

    @NotNull
    @Column(unique=true)
    private String name;

    //Getters and Setters

}

上面的代码创建了一个表 USER_SERVICES，但我还希望在表 USER_SERVICES 上与另一个表 RATINGS 建立多对多关系，这将导致另一个表 USER_SERVICES_RATINGS。如何使用 Hibernate/JPA 注释定义这种关系？

Answer 1

使用用户管理的连接表对象进行双向多对多(相对常见)

当您想要存储有关连接对象的额外信息(例如创建关系的日期)时通常使用。

public class Foo{
    private UUID fooId;

    @OneToMany(mappedBy = "bar", cascade=CascadeType.ALL)
    private List<FooBar> bars;
}

public class Bar{
    private UUID barId;

    @OneToMany(mappedBy = "foo", cascade=CascadeType.ALL)
    private List<FooBar> foos;
}

@Entity
@Table(name="FOO_BAR")
public class FooBar{
    private UUID fooBarId;

    @ManyToOne
    @JoinColumn(name = "fooId")
    private Foo foo;

    @ManyToOne
    @JoinColumn(name = "barId")
    private Bar bar;

    //You can store other objects/fields on this table here.
}