ManyToMany與額外的列的關係，並沒有使用Spring和休眠的複合關鍵概念

Question

我有兩個表：貿易和位置，並存在多對多的關係。現在我必須在中間表trade_location添加額外的列作爲「狀態」 。我搜索了很多，但提供的所有解決方案都是使用複合鍵。但我想要一個沒有複合鍵的解決方案作爲「trade_location」表作爲它自己的唯一主鍵作爲「id」。任何建議實現與extra列的manytomany關係和沒有組合鍵。 Thanks.Here是我的POJO：

enter code here 
      @Entity 
      @Table(name="trade") 
     public class Trade { 
    @Id 
    @GeneratedValue 
    private Long id; 
     @Column(unique=true) 
    private String name; 

    @OneToOne 
    @JoinColumn(name="sectorId") 
    private Sector sector; 

    @ManyToMany(mappedBy = "trades",fetch=FetchType.EAGER) 
    private Set<Location> location =new HashSet<Location>(); 
    public Long getId() { 
    return id; 
    } 

    @ManyToMany(mappedBy = "trades") 
    private Set<Trainee> trainee = new HashSet<Trainee>(); 
     //getter and setter here 
    } 

    @Entity 
    @Table(name="location") 
    public class Location implements Serializable{ 
    private static final long serialVersionUID = 1L; 
    @Id 
    @GeneratedValue 
    private Long id; 


    private String name; 
    private Long stateId; 
    private Long districtId; 
    private Long cityId; 
    private Long zoneId; 
    @Column(name="yearEstablishment") 
    private String yearOfEstablishment; 

    @ManyToMany(fetch=FetchType.EAGER) 
    @JoinTable(name = "trade_location", 
      joinColumns={@JoinColumn(name="locationId")}, 
      inverseJoinColumns={@JoinColumn(name="tradeId")}) 
    private Set<Trade> trades = new HashSet<Trade>(); 
     //getter and setter 
} 

//編輯一個

@Entity 
@Table(name="trade") 
public class Trade { 

@Id 
@GeneratedValue 
private Long id; 
@Column(unique=true) 
private String name; 

@OneToOne 
@JoinColumn(name="sectorId") 
private Sector sector; 

/*@ManyToMany(mappedBy = "trades",fetch=FetchType.EAGER) 
private Set<Location> location =new HashSet<Location>();*/ 

@OneToMany(mappedBy="trade") 
private Set<TradeLocation> tradeLocation = new HashSet<TradeLocation>(0); 

@ManyToMany(mappedBy = "trades") 
private Set<Trainee> trainee = new HashSet<Trainee>(); 

@OneToMany 
@JoinColumn(name="tradeId") 
private Set<Batch>batches =new HashSet<Batch>(); 
//getter and setter 

}

@Entity 

@Table（name = 「位置」） 公共類位置{

@Id 
@GeneratedValue 
private Long id; 


private String name; 
private Long stateId; 
private Long districtId; 
private Long cityId; 
private Long zoneId; 
@Column(name="yearEstablishment") 
private String yearOfEstablishment; 

/*@ManyToMany(fetch=FetchType.EAGER) 
@JoinTable(name = "trade_location", 
      joinColumns={@JoinColumn(name="locationId")}, 
      inverseJoinColumns={@JoinColumn(name="tradeId")}) 
private Set<Trade> trades = new HashSet<Trade>();*/ 

@OneToMany(mappedBy="location") 
private Set<TradeLocation>tradeLocation=new HashSet<TradeLocation>(0); 

/*getter and setter*/ 

}

@Entity 
@Table(name = "trade_location") 
public class TradeLocation implements Serializable { 
private static final long serialVersionUID = 1L; 

@Id 
@GeneratedValue 
private Long id; 

@ManyToOne(fetch=FetchType.LAZY) 
@JoinColumn(name="tradeId") 
private Trade trade; 

@ManyToOne(fetch=FetchType.LAZY) 
@JoinColumn(name="locationId") 
private Location location; 

//getter and setter 

}

Answer 1

你必須創建一個名爲實體TradeLocation如果你想讓它作爲一個id的獨立表。

並將您的關係更改爲關注。

Trade < - > 1 .. * TradeLocation *。1 < - >Location