我只是想知道在使用 Hibernate 注释创建数据库后如何创建对象?
当我运行下面的代码时,它会使用对象创建数据库,但是当我第二次运行时它只是创建完全相同的对象,并且没有添加任何新对象?怎么来的?在使用注释创建数据库后,如何使用 .save 方法使用注释创建对象?还是不能使用注释来做到这一点?
提前致谢。
public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
Adress adress = new Adress("Streetname", "postcode");
Person person1 = new Person("Peter Hanks", adress);
Person person2 = new Person("Sophie Hanks", adress);
session.save(person1);
session.save(person2);
transaction.commit();
} catch (HibernateException e) {
transaction.rollback();
e.printStackTrace();
} finally {
session.close();
}
}
这是代码 person.class
@Entity
@Table(name="person")
public class Person implements Serializable {
private long id;
private String navn;
private Adresse adresse;
public Person() {
}
public Person(String navn, Adresse adresse) {
this.navn = navn;
this.adresse = adresse;
}
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name= "adresse_id", nullable = false)
public Adresse getAdresse() {
return adresse;
}
public void setAdresse(Adresse adresse) {
this.adresse = adresse;
}
@Id
@GeneratedValue
@Column(name= "id")
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
@Column(name = "navn", nullable= false, length= 100)
public String getNavn() {
return navn;
}
public void setNavn(String navn) {
this.navn = navn;
}
@Override
public int hashCode() {
int hash = 3;
hash = 29 * hash + (this.navn != null ? this.navn.hashCode() : 0);
hash = 29 * hash + (this.adresse != null ? this.adresse.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Person other = (Person) obj;
if ((this.navn == null) ? (other.navn != null) : !this.navn.equals(other.navn)) {
return false;
}
if (this.adresse != other.adresse && (this.adresse == null || !this.adresse.equals(other.adresse))) {
return false;
}
return true;
}