多對多的關係：org.hibernate.MappingException：無法確定類型：java.util.Set中

Question

我試圖建立一個多基於這個例子與JPA許多雙向關係：http://www.mkyong.com/hibernate/hibernate-many-to-many-example-join-table-extra-column-annotation/

我米得到一個

org.hibernate.MappingException：無法確定類型：java.util.Set中，在表中：T_ITEM，對於列：[org.hibernate.mapping.Column（itemHikes）]

如果有人能幫助我，那就是下面的源代碼：

類物品

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

    @Id 
    private Long id; 
    private Set<ItemHike> itemHikes = new HashSet<ItemHike>(0); 

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.item", cascade=CascadeType.ALL) 
    public Set<ItemHike> getItemHikes() { 
     return this.itemHikes; 
    } 

    public void setItemHikes(Set<ItemHike> itemHikes) { 
     this.itemHikes = itemHikes; 
    } 
} 

類遠足

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

    @Id 
    private Long id; 

    private List<ItemHike> itemHikes = new ArrayList<ItemHike>(0); 

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.hike", cascade=CascadeType.ALL) 
    public List<ItemHike> getItemHikes() { 
     return this.itemHikes; 
    } 

    public void setItemHikes(List<ItemHike> itemHikes) { 
     this.itemHikes = itemHikes; 
    } 
} 

類ItemHike

@Entity 
@Table(name="T_ITEM_HIKE") 
@AssociationOverrides({ 
    @AssociationOverride(name = "pk.item", 
     joinColumns = @JoinColumn(name = "iditem")), 
    @AssociationOverride(name = "pk.hike", 
     joinColumns = @JoinColumn(name = "idlist")) }) 


public class ItemHike implements Serializable { 
    private static final long serialVersionUID = 1L; 

    @EmbeddedId 
    private ItemHikePK pk; 

    private int quantity; 

    //bi-directional many-to-one association to THike 

    @Transient 
    public Item getItem() { 
     return getPk().getItem(); 
    } 

    public void setItem(Item item) { 
     getPk().setItem(item); 
    } 


    @Transient 
    public Hike getHike() { 
     return getPk().getHike(); 
    } 

    public void setHike(Hike hike) { 
     getPk().setHike(hike); 
    } 

    public ItemHike() { 
    } 

    public ItemHikePK getPk() { 
     return this.pk; 
    } 

    public void setPk(ItemHikePK pk) { 
     this.pk = pk; 
    } 

    public int getQuantity() { 
     return this.quantity; 
    } 

    public void setQuantity(int quantity) { 
     this.quantity = quantity; 
    } 
} 

類ItemHikePk

@Embeddable 
public class ItemHikePK implements Serializable { 
    //default serial version id, required for serializable classes. 
    private static final long serialVersionUID = 1L; 

    private Item item; 
    private Hike hike; 

    @ManyToOne 
    public Item getItem() { 
     return item; 
    } 

    public void setItem(Item item) { 
     this.item = item; 
    } 

    @ManyToOne 
    public Hike getHike() { 
     return hike; 
    } 

    public void setHike(Hike hike) { 
     this.hike = hike; 
    } 
} 

Answer 1

嘗試將@OneToMany註釋從getItemHikes()移動到itemHikes字段。如果您希望註釋有時位於字段上，有時位於getter上，則需要使用@Access註釋。如果您不使用它，則所有註釋都需要在字段或獲取者上，但不能混合使用。

Answer 2

Here is a similiar question !

你設置的字段@Anottations太上吸氣劑，這是錯誤的，你必須穿上字段或上吸氣劑方法的註釋。

錯誤方式：

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

    @Id 
    private Long id; 
    private Set<ItemHike> itemHikes = new HashSet<ItemHike>(0); 

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.item", cascade=CascadeType.ALL) 
    public Set<ItemHike> getItemHikes() { 
     return this.itemHikes; 
    } 

    public void setItemHikes(Set<ItemHike> itemHikes) { 
     this.itemHikes = itemHikes; 
    } 
} 

正確：

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

    @Id 
    private Long id; 
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.item", cascade=CascadeType.ALL) 
    private Set<ItemHike> itemHikes = new HashSet<ItemHike>(0); 

    public Set<ItemHike> getItemHikes() { 
     return this.itemHikes; 
    } 

    public void setItemHikes(Set<ItemHike> itemHikes) { 
     this.itemHikes = itemHikes; 
    } 
}