Question

嗨任何人都可以帮我解决这个异常。这里我有一个名为Person的实体类，而实例变量的Person类有name和petnames，这里的petnames我把它作为数据类型为集合的简单值类型。只需查看我的以下代码和正在生成的相应异常。我这么多天都面临着这个例外。我正在努力解决这个问题我不会在哪里出错。

人员类

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;
    @ElementCollection
    @CollectionTable(name = "petname")
//    @Column(name = "ColumnName")
    private Set<String> petname = new HashSet<String>();

    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPetname(Set<String> petname) {
        this.petname = petname;
    }

    public Set<String> getPetname() {
        return petname;
    }

    public boolean addPets(String p) {
        return petname.add(p);
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Person)) {
            return false;
        }
        Person other = (Person) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.myapp.struts.Person[ id=" + id + " ]";
    }

例外：

Initial SessionFactory creation failed.org.hibernate.MappingException: Could not determine type for: java.util.Set, for columns: [org.hibernate.mapping.Column(petname)]
Exception in thread "main" java.lang.ExceptionInInitializerError
    at com.myapp.struts.NewHibernateUtil.<clinit>(NewHibernateUtil.java:28)
    at com.myapp.struts.Test.main(Test.java:16)
Caused by: org.hibernate.MappingException: Could not determine type for: java.util.Set, for columns: [org.hibernate.mapping.Column(petname)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:266)
    aJava Result: 1

Answer 1

考虑改变这个

@ElementCollection
@CollectionTable(name = "petname")
private Set<String> petname = new HashSet<String>();

我的意思是将ElementCollection和Collectiontable注释一起移到字段上方。

如果要更改列的名称，请使用此名称。

@ElementCollection
@CollectionTable(name = "petname")
@Column(name="ColumnName")
private Set<String> petname = new HashSet<String>();

当您使用String基本类型时，也不需要joinColumns = @JoinColumn(name = "PERSON_ID"。

Answer 2

首先，JPA注释必须全部在属性上设置，或者在getter上设置。不是两者兼而有之，也不是同一个实体。

其次，试试：

@ElementCollection
@CollectionTable(name = "petname", joinColumns = {@JoinColumn(name = "<column id name in Petname>", nullable = false, referencedColumnName = "<column id name in Person>")})
@Column(name="<column name for petname>")
private Set<String> petname = new HashSet<String>();

@CollectionTable和@ElementCollection正在生成异常

2 个答案: