关于jpa：多对多关系：org.hibernate.MappingException：无法确定类型：java.util.Set

many to many relationship : org.hibernate.MappingException: Could not determine type for: java.util.Set

我正试图基于以下示例与JPA建立多对多双向关系：http://www.mkyong.com/hibernate/hibernate-many-to-many-example-join-table-extra-column-annotation/

我得到一个

org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: T_ITEM, for columns: [org.hibernate.mapping.Column(itemHikes)]

号

如果有人能帮我的话，下面是源代码：

类项目

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@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;
}
}

班级远足

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@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;
}
}

号

课程项目

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@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;
}
}

类itemhikepk

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@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;
}
}

。

这是一个类似的问题！

您在字段和getter上设置了@anotations，这是错误的，您必须在字段或getter方法上放置注释。

错误的方式：

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对的：

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@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;
}
}

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