Question

我创建了两个类，它们之间有多对多关系，如下所示：

@Entity
@Table(name = FoodEntity.TABLE_NAME)
public class FoodEntity extends BaseEntity<Long> {

public static final String TABLE_NAME = "T_FOOD";

@ManyToMany
@JoinTable(
    name = "T_FOOD_FOODCATEGORY",
    joinColumns =       { @JoinColumn(name = "FOOD_ID") }, 
    inverseJoinColumns =    { @JoinColumn(name = "FOOD_CATEGORY_ID") })
private Set<FoodCategoryEntity> categories;

public Set<FoodCategoryEntity> getCategories() {
return categories;
}

public void setCategories(Set<FoodCategoryEntity> categories) {
this.categories = categories;
}

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "FOOD_ID", nullable = false)
@Override
public Long getId() {
return id;
}

@Override
public void setId(Long id) {
this.id = id;
}

}

和：

@Entity
@Table(name = FoodCategoryEntity.TABLE_NAME)
public class FoodCategoryEntity extends BaseEntity<Long> {

public static final String TABLE_NAME = "T_FOOD_CATEGORY";

@ManyToMany(mappedBy = "categories")
private Set<FoodEntity> foods;

public Set<FoodEntity> getFoods() {
return foods;
}

public void setFoods(Set<FoodEntity> foods) {
this.foods = foods;
}

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "FOOD_CATEGORY_ID", nullable = false)
@Override
public Long getId() {
return id;
}

@Override
public void setId(Long id) {
this.id = id;
}

}

但是当我用junit，spring和hibernate测试这个关系时，我得到以下异常：

Caused by: org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: T_FOOD, for columns: [org.hibernate.mapping.Column(categories)]
at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:455)
at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:422)
at org.hibernate.mapping.Property.isValid(Property.java:226)
at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:597)
at org.hibernate.mapping.RootClass.validate(RootClass.java:265)
at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:329)
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:451)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:889)
... 46 more

我检查了注释包引用和所有ID列名，但所有这些都是正确的。 point：我还使用HSQLDB数据库，它的存储位置是文件。

Answer 1

我发现了我的问题。 persistence.xml中的映射类不正确。

Answer 2

您的注释推断属性访问类型映射，因为@Id放置在getter

上

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "FOOD_ID", nullable = false)
@Override
public Long getId() {
    return id;
}

但收集注释放在字段级别

@ManyToMany
@JoinTable(
    name = "T_FOOD_FOODCATEGORY",
    joinColumns =       { @JoinColumn(name = "FOOD_ID") }, 
    inverseJoinColumns =    { @JoinColumn(name = "FOOD_CATEGORY_ID") })
private Set<FoodCategoryEntity> categories;

虽然在getter上指定了（未）有效配置

public Set<FoodCategoryEntity> getCategories() {
    return categories;
}

您不应混用两种类型的配置。

无法确定：java.util.Set的类型，在表中

2 个答案: