JPA 2.0：三個實體之間的映射

Question

我想使用JPA 2.0實現以下關係。 Entity Diagram
簡而言之：用戶可以在一個組中擁有多個角色。
有沒有一種方便的方法來實現這一目標？一個代碼示例會很好。

在此先感謝！

Answer 1

public class Users implements Serializable { 
private static final long serialVersionUID = 1L; 
@Basic(optional = false) 
@NotNull 
@Size(min = 1, max = 10) 
@Column(name = "id_usuario") 
private Integer idUsuario; 
@Basic(optional = false) 
@NotNull 
@Size(min = 1, max = 80) 
@Column(name = "nombre") 
private String nombre; 
@OneToMany(cascade = CascadeType.ALL, mappedBy = "Users") 
private Collection<NzSistemaControl> nzSistemaControlCollection; 

角色

public class Roles implements Serializable { 
private static final long serialVersionUID = 1L; 
@Id 
@Basic(optional = false) 
@NotNull 
@Column(name = "id_rol") 
private Integer idRol; 
@Basic(optional = false) 
@NotNull 
@Size(min = 1, max = 50) 
@Column(name = "nombre") 
private String nombre; 
@OneToMany(cascade = CascadeType.ALL, mappedBy = "Roles") 
private Collection<NzSistemaControl> nzSistemaControlCollection; 

關係表

public class SistemaControl implements Serializable { 
@EmbeddedId 
protected NzSistemaControlPK nzSistemaControlPK; 
@JoinColumn(name = "id_usuario", referencedColumnName = "id_usuario_sistema", insertable = false, updatable = false) 
@ManyToOne(optional = false) 
private Users user; 
@JoinColumn(name = "id_rol", referencedColumnName = "id_rol", insertable = false, updatable = false) 
@ManyToOne(optional = false) 
private Roles roles; 

RelationShipPK

public class NzSistemaControlPK implements Serializable { 
@Basic(optional = false) 
@NotNull 
@Column(name = "id_usuario") 
private int idUsuario; 
@Basic(optional = false) 
@NotNull 
@Column(name = "id_rol") 
private int idRol;