我对 JAVA JPA 中的 @Embeddable 有一些问题。我有一个名为“作者”的实体类：
@Entity
@Table(name = "author")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Author.findAll", query = "SELECT a FROM Author a"),
...})
public class Author implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Basic(optional = false)
@Column(name = "aID")
private Integer aID;
@Column(name = "aName")
private String aName;
@Column(name = "aSurname")
private String aSurname;
@Column(name = "aPhone")
private Integer aPhone;
@Embedded
@AttributeOverrides({
@AttributeOverride(name="city",column=@Column(name="Address")),
@AttributeOverride(name="street",column=@Column(table="Address")),
@AttributeOverride(name="number",column=@Column(table="Address"))
}) private Address address;
// set and get methods.
}
我还有一个名为“Address”的可嵌入类：
@Embeddable
@Table(name = "Address")
@XmlRootElement
public class Address implements Serializable
{
private static final long serialVersionUID=1L;
@Column(name="city")
private String city;
@Column(name="street")
private String street;
@Column(name="number")
private int number;
// get and set methods.
}
在我的主类中，我想将此值插入数据库。（我使用 mySQL）但我在这一行遇到错误：em.getTransaction.commit();
public class CreateAuthor extends javax.swing.JFrame {
private static final String PERSISTENCE_UNIT_NAME = "Project";
private static EntityManagerFactory emf;
public void CreateAuthor() {
initComponents();
}
private void ekleButtonActionPerformed(java.awt.event.ActionEvent evt) {
emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
Author author = new Author();
author.setAID(3);
author.setAName("Sheldon");
author.setASurname("Smith");
author.setAPhone(768987);
Address adr = new Address();
adr.setCity("Paris");
adr.setStreet("cinar");
adr.setNumber(12);
author.setAddress(adr);
em.persist(author);
em.getTransaction().commit(); /// error occured
em.close();
}
}
在我的数据库方面，我有 Author 表 (aID(pk),aName,aSurname,aPhone)
地址表（城市、街道、号码）
你知道为什么会发生错误吗？