Hibernate 系列教程12-继承-Join策略

最新推荐文章于 2021-02-16 16:11:05 发布

JE_GE

最新推荐文章于 2021-02-16 16:11:05 发布

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本文介绍了一个使用Hibernate框架进行对象关系映射的示例，包括基本的员工类及其派生类时薪员工和月薪员工的定义与配置，并演示了如何保存和获取这些实体。

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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">
        <id name="id">
            <generator class="native" />
        </id>
        <property name="name" />
        <!-- 在配置子类 -->
        <joined-subclass name="HourlyEmployee" table="t_HourlyEmployee">
            <key column="id"/>
            <property name="rate" />
        </joined-subclass>
        <joined-subclass name="SalariedEmployee" table="t_SalariedEmployee">
            <key column="id"/>
            <property name="salary" />
        </joined-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();
  }
}