java - Hibernate 实体 - 向实体添加业务逻辑？

Question

我有实体:

@Entity(name = "Term")
@Table(name = "extra_term")
public class Term implements Cloneable, Serializable{

这个实体有ID

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

并且该实体具有该实体拥有的用户列表的属性(用户已注册到术语)

@OneToMany(cascade = CascadeType.ALL)
@JoinTable(name = "etc. etc. etc. })    
private List<TermUser> users = new ArrayList<TermUser>();   

是否可以声明业务方法来统计该用户注册到具体期限的总和？有点像

public long getUsersCount() {
  return QUERY TO THE DATABASE "GET COUNT OF USERS REGISTERED TO TERM WITH ID
  (where ID is the id of this entity?)"
}

我需要直接从 entitz 计算注册到 term 的用户数量，但我不想在数据库中有一个属性“registeredUsersCount”。

Answer 1

这正是@Transient是为了。

Every non static non transient property (field or method depending on the access type) of an entity is considered persistent, unless you annotate it as @Transient.