Single Table策略
通过 discriminator鉴别器来区分是父类还是子类
Employee
public class Employee {
private Long id;
private String name;HourlyEmployee
public class HourlyEmployee extends Employee {
private Double rate;SalariedEmployee
public class SalariedEmployee extends Employee {
private Double salary;Employee.hbm.xml
<class name="Employee" table="t_employee" discriminator-value="1">
<id name="id">
<generator class="native" />
</id>
<!-- 在id之后配置discriminator的数据库类型的字段名称 ,以及类型(默认是string) -->
<discriminator column="types" type="int" />
<property name="name" />
<!-- 在配置子类 -->
<subclass name="HourlyEmployee" discriminator-value="2">
<property name="rate"/>
</subclass>
<subclass name="SalariedEmployee" discriminator-value="3">
<property name="salary" />
</subclass>
</class>MainTest
public class MainTest {
Session session = null;
@Before
public void save() {
session = HibernateUtils.INSTANCE.getSession();
session.beginTransaction();
Employee employee = new Employee("jege");
HourlyEmployee hourlyEmployee = new HourlyEmployee();
hourlyEmployee.setName("hourly");
hourlyEmployee.setRate(200D);
SalariedEmployee salariedEmployee = new SalariedEmployee();
salariedEmployee.setName("salaried");
salariedEmployee.setSalary(300D);
session.save(employee);
session.save(hourlyEmployee);
session.save(salariedEmployee);
}
@Test
public void get() {
Employee employee = (Employee) session.get(Employee.class, 1L);
System.out.println(employee.getName());
HourlyEmployee hourlyEmployee = (HourlyEmployee) session.get(HourlyEmployee.class, 2L);
System.out.println(hourlyEmployee.getName());
System.out.println(hourlyEmployee.getRate());
SalariedEmployee salariedEmployee = (SalariedEmployee) session.get(SalariedEmployee.class, 3L);
System.out.println(salariedEmployee.getName());
System.out.println(salariedEmployee.getSalary());
}
@After
public void colse() {
session.getTransaction().commit();
session.close();
}
}
源码地址
https://github.com/je-ge/hibernate
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