相同表的Hibernate扩展实体

如果要在所需表中保存公共字段，则意味着假设您拥有A类和B类，并且具有一些通用文件（例如created_by，updated_by），并且希望将field1，field2保存在两个实体中：IN数据库级：

query> select * from A;+----++------------------------+| id | created_by | updated_by |+----+------------+------------+|  3 |    xyz     | abc        |+----+------------+------------+query> select * from B; +----++------------------------+| id | created_by | updated_by |+----+------------+------------+|  3 |    xyz     | abc        |+----+------------+------------+

对于这种类型的结构，您应该使用@MappedSuperclass，就像@Dragan Bozanovic建议的那样

但是，如果您需要“父子”关系并要为每个类生成表，则可以使用@Inheritance（strategy =
InheritanceType.TABLE_PER_CLASS）来为每个类创建表，例如：假设您有2个类Payment和CreditCard，Payment是CreditCard的父类。

@Entity@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)public class Payment {    @Id    @GeneratedValue(strategy = GenerationType.TABLE)    private int id;    @Column(nullable = false)    private double amount;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public double getAmount() {        return amount;    }    public void setAmount(double amount) {        this.amount = amount;    }}@Entitypublic class CreditCard extends Payment {private String ccNumber;private Date expireDate;    public String getCcNumber() {        return ccNumber;    }    public void setCcNumber(String ccNumber) {        this.ccNumber = ccNumber;    }    public Date getExpireDate() {        return expireDate;    }    public void setExpireDate(Date expireDate) {        this.expireDate = expireDate;    }}

现在，您将保存日期：

public class TestConcreteClasses {    public static void main(String[] args) {        Payment payment = new Payment();        payment.setAmount(52.6);        createData(payment);        CreditCard creditCard = new CreditCard();        creditCard.setAmount(10);        creditCard.setCcNumber("2536985474561236");        creditCard.setExpireDate(new Date());        createData(creditCard);    }    private static void createData(Payment instance) {        Session session = HibernateUtil.getSession();        session.beginTransaction();        session.save(instance);        session.getTransaction().commit();    }}

然后数据将保存为

query> select * from Payment;+----+--------+| id | amount |+----+--------+|  1 |   52.6 |+----+--------+1 row in set (0.00 sec) select * from CreditCard;+----+--------+------------------+---------------------+| id | amount | ccNumber         | expireDate          |+----+--------+------------------+---------------------+|  2 |     10 | 2536985474561236 | 2017-03-12 14:10:15 |+----+--------+------------------+---------------------+1 row in set (0.00 sec)

hibernate中使用了3种类型的继承，这是用于继承的hibernate文档
https://docs.jboss.org/hibernate/jpa/2.1/api/javax/persistence/InheritanceType.html，您应该根据以下条件进行选择您的要求。