java - Hibernate 多对多映射，使用 PK 和额外列连接表

Question

我已经对概述的模型进行了必要的更改 here 。但是，我不知道要在我的连接表实体上放置什么。

请注意，我的连接表有一个代理键和两个额外的列(日期和 varchar)。

到目前为止我得到的是:

用户.java

@Entity
@Table (name = "tbl_bo_gui_user")
@DynamicInsert
@DynamicUpdate
public class User implements Serializable {
    private String id;
    private String ntName;
    private String email; 
    private Set<GroupUser> groupUsers = new HashSet<GroupUser>(0);

    // Constructors and some getters setters omitted

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.user", cascade=CascadeType.ALL)
    public Set<GroupUser> getGroupUsers() {
        return groupUsers;
    }

    public void setGroupUsers(Set<GroupUser> groupUsers) {
        this.groupUsers = groupUsers;
    }
}

Group.java

@Entity
@Table (name = "tbl_bo_gui_group")
@DynamicInsert
@DynamicUpdate
public class Group implements Serializable {
    private String id;
    private String groupName;
    private String groupDesc;
    private Set<GroupUser> groupUsers = new HashSet<GroupUser>(0);

    // Constructors and some getters setters omitted

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.group", cascade=CascadeType.ALL)
    public Set<GroupUser> getGroupUsers() {
        return groupUsers;
    }

    public void setGroupUsers(Set<GroupUser> groupUsers) {
        this.groupUsers = groupUsers;
    }
}

问题是我不知道要在我的连接表实体上放置什么。在这里。

GroupUser.java

@Entity
@Table (name = "tbl_bo_gui_group_user")
@DynamicInsert
@DynamicUpdate
@AssociationOverrides({
    @AssociationOverride(name = "pk.user", 
            joinColumns = @JoinColumn(name = "id")),
    @AssociationOverride(name = "pk.group", 
            joinColumns = @JoinColumn(name = "id")) })
public class GroupUser implements Serializable {
    private String id;
    private User userId;
    private Group groupId;
    private Date dateCreated;
    private String createdBy;

    // constructors and getters and setters for each property

    // What now? ? No idea
}

Answer 1

用户与组之间是一种多对多关系。现在，您将其分成两个一对多关系。因此，您的映射实体只需使用多对一来完成多对多关系:

public class GroupUser implements Serializable {
    private String id;

    @ManyToOne
    private User userId;

    @ManyToOne
    private Group groupId;
    private Date dateCreated;
    private String createdBy;
}

另请参阅此示例:Mapping many-to-many association table with extra column(s) (38票赞成的答案)