休眠：org.hibernate.MappingException：无法确定类型：java.util.Set

Question

我正在尝试在休眠中使用 Set。我不知道如何在 Set 表上写注解的问题。

    @Entity
    @Table(name="user_settings")
    public class UserSettings {
    @Id
    @GeneratedValue
    private int id;
    private int userid;
    protected Set<Integer>foreignLanguageId;
    public UserSettings() {   

    }
    public UserSettings(int userid, int nativeLanguageId,
            Set<Integer> foreignLanguageId, Date birthday) {
        this.userid = userid;
        this.nativeLanguageId = nativeLanguageId;
        this.foreignLanguageId = foreignLanguageId;
        this.birthday = birthday;
    }

    @OneToMany
    @JoinColumn(name="userid", nullable=false)// This annotation
    public Set<Integer> getForeignLanguageId() {
        return foreignLanguageId;
    }

错误：

org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: user_settings, for columns: [org.hibernate.mapping.Column(foreignLanguageId)]
at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:314)...........

Answer 1

你应该使用实体来建立关联而不是id

@Entity
@Table(name="user_settings")
public class UserSettings {

    private Set<Language> foreignLanguages;

    @OneToMany
    @JoinColumn(name="fk_user_setting", nullable = false)
    public Set<Language> getForeignLanguages() {
        return foreignLanguages;
    }

}

如果你想使用Integer，你可以使用@ElementCollection

@Entity
@Table(name="user_settings")
public class UserSettings {

    private Set<Integer> foreignLanguages;

    @ElementCollection
    public Set<Integer> getForeignLanguages() {
        return foreignLanguages;
    }

}