我的 hibernate 项目具有以下设计:

@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;
    }
}

如您所见,用户与个人资料之间存在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;
    }
}

如果现在尝试创建员工,则会出现 hibernate 异常:



我如何使用ManyToMany-Relationship对父类(super class)User进行概要分析,因此它适用于ClientEmployee

最佳答案

问题在于对User的引用,它不是一个实体。外键只能引用一个表。使用@ManyToAny(可以处理多个表),或者使用@Inheritance(strategy = InheritanceType.SINGLE_TABLE),它将所有实体都放在一个表上。

这是 hibernate 中有关继承的文档:http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#d0e1168

关于java - @ManyToMany在抽象的MappedSuperclass中,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/4045511/

10-13 01:13