@ManyToMany在一个抽象的MappedSuperclass中

Question

我的hibernate项目有以下设计:

@MappedSuperclass
public abstract class User {
    private List<Profil>    profile;

    @ManyToMany (targetEntity=Profil.class)
    public List<Profil> getProfile(){
        return profile;
    }
    public void setProfile(List<Profil> profile) {
        this.profile = profile;
    }
}

@Entity
@Table(name="client")
public class Client extends User {
    private Date    birthdate;
    @Column(name="birthdate")
    @Temporal(TemporalType.TIMESTAMP)
    public Date getBirthdate() {
        return birthdate;
    }
    public void setBirthdate(Date birthdate) {
        this.birthdate= birthdate;
    }
}

@Entity
@Table(name="employee")
public class Employee extends User {
    private Date    startdate;
    @Column(name="startdate")
    @Temporal(TemporalType.TIMESTAMP)
    public Date getStartdate() {
        return startdate;
    }
    public void setStartdate(Date startdate) {
        this.startdate= startdate;
    }
}

正如您所看到的,用户可以看到与Profile的ManyToMany关系.

@Entity
@Table(name="profil")
public class Profil extends GObject {
    private List<User>  user;

    @ManyToMany(mappedBy = "profile", targetEntity = User.class )
    public List<User> getUser(){
        return user;
    }
    public void setUser(List<User> user){
        this.user = user;
    }
}

如果我现在尝试创建一个员工,我会得到一个hibernate异常:

org.hibernate.AnnotationException:使用@OneToMany或@ManyToMany定位未映射的类:de.ke.objects.bo.profile.Profil.user [de.ke.objects.bo.user.User]

如何在超类上使用ManyToMany-Relationship配置文件User,因此适用于Client和Employee？

Answer 1

问题在于对 User 的引用，它不是一个实体。一个外键只能引用一张表。使用@ManyToAny（可以处理多个表）或@Inheritance(strategy=InheritanceType.SINGLE_TABLE)（它将所有实体放入一张表中）。

这是有关休眠中继承的文档：http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#d0e1168