许多-to-many关联与额外的列

Question

我不能够正确地映射即使按照提供的所有步骤： https://www.mkyong.com/hibernate/hibernate-many-to-many-example-join-table-extra-column-annotation/

CREATE TABLE `tb_pla_playlist` (
`id_playlist` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, 
`nm_playlist` VARCHAR(10) NOT NULL, 
PRIMARY KEY (`id_playlist`) USING BTREE, 
) 
CREATE TABLE `tb_mid_midia` (
`id_midia` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, 
`nm_midia` VARCHAR(10) NOT NULL, 
PRIMARY KEY (`id_midia`) USING BTREE 
) 
CREATE TABLE `tb_mip_midia_playlist` (
`id_midia` INT(10) UNSIGNED NOT NULL, 
`id_playlist` INT(10) UNSIGNED NOT NULL, 
`nr_ordem` INT(10) UNSIGNED NOT NULL, 
`CREATED_BY` VARCHAR(10) NOT NULL, 
PRIMARY KEY (`id_midia`,`CATEGORY_ID`), 
CONSTRAINT `FK_id_midia` FOREIGN KEY (`id_midia`) 
     REFERENCES `midia` (`id_midia`), 
CONSTRAINT `FK_id_playlist` FOREIGN KEY (`id_playlist`) 
     REFERENCES `playlist` (`id_playlist`) 
) 

playlist.java

@Entity 
@Table(name="tb_pla_playlist") 
public class Playlist implements Serializable { 
private Set<MidiaPlaylist> midiaPlaylist = new HashSet<MidiaPlaylist>(); 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name="id_playlist") 
private Long idPlaylist; 

@OneToMany(mappedBy = "id.playlist", cascade = CascadeType.ALL) 
private Set<MidiaPlaylist> getMidiaPlaylist(){ 
    return midiaPlaylist; 
} 
... 
} 

[埃罗：在属性'midiaPlaylist'，“映射”值'id.playlist'无法解析为目标实体上的属性。]

midia.java

@Entity 
@Table(name="tb_mid_midia") 
public class Midia implements Serializable { 
private Set<MidiaPlaylist> midiaPlaylist = new HashSet<MidiaPlaylist>(); 

@Id 
@GeneratedValue 
@Column(name="id_midia") 
private Long idMidia; 

@OneToMany(mappedBy = "id.midia", cascade=CascadeType.ALL) 
public Set<MidiaPlaylist> getMidiasPlaylist() { 
    return midiaPlaylist; 
} 

[埃罗：在属性 'midiasPlaylist'，值 'id.midia' “由映射” 不能被解析到目标实体的属性]

MidiaPlaylistPK.java

@Embeddable 
public class MidiaPlaylistPK implements Serializable { 
    private Midia midia; 
private Playlist playlist; 

@ManyToOne(cascade = CascadeType.ALL) 
public Midia getMidia(){ 
    return midia; 
} 
public void setMidia(Midia midia){ 
    this.midia = midia; 
} 

@ManyToOne(cascade = CascadeType.ALL) 
public Playlist getPlaylist(){ 
    return playlist; 
} 

public void setPlaylist(Playlist playlist){ 
    this.playlist = playlist; 
} 
} 

MidiaPlaylist.java

@Entity 
@Table(name="tb_mip_midia_playlist") 
@AssociationOverrides({ 
    @AssociationOverride(name="id.playlist", [erro: Persistent type of override attribute "id.playlist" cannot be resolved] 
    joinColumns = @JoinColumn(name = "id_playlist")), 
    @AssociationOverride(name="id.midia", [erro: Persistent type of override attribute "id.midia" cannot be resolved] 
    joinColumns = @JoinColumn(name = "id_midia")) 
    }) 
public class MidiaPlaylist implements Serializable { 
private MidiaPlaylistPK id = new MidiaPlaylistPK(); 
private int nrOrdem; 

@EmbeddedId [erro: Embedded ID class should not contain relationship mappings] 
public MidiaPlaylistPK getId() { 
    return this.id; 
} 
@Column(name="nr_ordem", nullable=false) 
public int getNrOrdem(){ 
    return this.nrOrdem; 
} 

@Transient 
public Midia getMidia(){ 
    return getId().getMidia(); 
} 

@Transient 
public Playlist getPlaylist(){ 
    return getId().getPlaylist(); 
} 

Relational model

有人可以帮我解决这些错误吗？泰！

Answer 1

您应该删除@ManyToOne anotation在@Embeddable，并使用@MapId anotation insted的的@Transient，这里有个例子： http://www.objectdb.com/api/java/jpa/MapsId