java - org.hibernate.AnnotationException 映射错误

Question

我正在尝试用元素制作购物车。一个用户有多个项目，所以我这样做:我有一个 @Entity @Table 类 Item，它实现了 Serialized

private User user;

...

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}


@OneToMany(cascade = ALL, fetch = FetchType.EAGER, mappedBy = "items")
@Column(nullable = true, updatable = false)
public User getUser() {
    return user;
}

在 User.java 中(@Entity @Table 实现 Serialized):

private List<Item> items; 
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

...

@ManyToOne
public List<Item> getItems() {
    return items;
}

public void setItems(List<Item> items) {
    this.items = items;
}

我得到的是这个错误:

Caused by: org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: org.auction.model.Item.user"}}

Answer 1

您的注释混淆了，@OneToMany 是集合的注释

在 Items 类中

 @ManyToOne(cascade = ALL, fetch = FetchType.EAGER)
 @Column(nullable = true, updatable = false)
  public User getUser() {
   return user;
  }

在用户类中，您将拥有 OneToMany

@OneToMany(mappedBy = "user")
public List<Item> getItems() {
   return items;
}