hibernate.cfg.xml中如何配置物理命名策略？

Question

我正在学习 Java 和 Hibernate。现在，我很难理解如何使用自定义物理命名策略：虽然 PhysicalNamingStrategy 对象确实已实例化，但从未调用过 toPhysicalTableName 或 toPhysicalColumnName 方法——这不是我可以用调试器看到的，至少。

版本：Java 1.8、Hibernate 5.2.10.Final、macOS 10.12。

这是一个最小的项目：

@Entity
public class Cake {
    @Id
    private long id;
    private String name;
    private String FLAVOUR;
    private int sErViNg;

    public Cake(String name, String flavour, int serving) {
        this.name = name;
        this.FLAVOUR = flavour;
        this.sErViNg = serving;
    }

    // getters and setters

---

public class Main {

    public static void main (String[] args) {
        Transaction tx = null;

        try (
                SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
                Session session = sessionFactory.openSession();
        ) {
            tx = session.beginTransaction();

            Cake cake = new Cake("Molten Chocolate Cake", "chocolate", 1);
            session.save(cake);

            tx.commit();
        }
        catch (Exception e) {
            e.printStackTrace();
            if ( tx != null  ) {
                tx.rollback();
            }
        }
    }
}

---

public class AllCapsPhysicalNamingStrategy
    extends PhysicalNamingStrategyStandardImpl implements Serializable {

    public static final AllCapsPhysicalNamingStrategy INSTANCE
        = new AllCapsPhysicalNamingStrategy();

    @Override
    public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment context) {
        return new Identifier(name.getText().toUpperCase(), name.isQuoted());
    }

    @Override
    public Identifier toPhysicalColumnName(Identifier name, JdbcEnvironment context) {
        return new Identifier(name.getText().toUpperCase(), name.isQuoted());
    }
}

---

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost/cake</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password"></property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
        <property name="hibernate.hbm2ddl.auto">create</property>
        <property name="hibernate.physical_naming_strategy">com.example.AllCapsPhysicalNamingStrategy</property>
        <mapping class="com.example.Cake"/>
    </session-factory>
</hibernate-configuration>

---

这是我得到的表格：

[cake]> SELECT * FROM cake;
+----+-----------+-----------------------+---------+
| id | FLAVOUR   | name                  | sErViNg |
+----+-----------+-----------------------+---------+
|  0 | chocolate | Molten Chocolate Cake |       1 |
+----+-----------+-----------------------+---------+

我希望：

+----+-----------+-----------------------+---------+
| ID | FLAVOUR   | NAME                  | SERVING |
+----+-----------+-----------------------+---------+
|  0 | chocolate | Molten Chocolate Cake |       1 |
+----+-----------+-----------------------+---------+

我在这里做错了什么？

Answer 1

这没有很好的记录，但不幸的是，Hibernate 似乎不支持在 hibernate.cfg.xml 中设置的特定属性。引用a very old Hibernate forum post:

您只能在给定 Environment.java 类中设置属性 hibernate.properties 或 hibernate.cfg.xml。其余属性如 NamingStrategy 必须使用 Configuration 类进行配置。

因此建议删除该属性，而是按照 Shiv Raghuwanshi 的建议在 Configuration 实例的代码中设置它。

Answer 2

您也可以在配置中设置。

public class Main {

public static void main (String[] args) {
    Transaction tx = null;

    try (
            Configuration configuration =new Configuration();
            configuration.setPhysicalNamingStrategy(new AllCapsPhysicalNamingStrategy());
            SessionFactory sessionFactory = configuration.configure().buildSessionFactory();
            Session session = sessionFactory.openSession();
    ) {
        tx = session.beginTransaction();

        Cake cake = new Cake("Molten Chocolate Cake", "chocolate", 1);
        session.save(cake);

        tx.commit();
    }
    catch (Exception e) {
        e.printStackTrace();
        if ( tx != null  ) {
            tx.rollback();
        }
    }
  }
}

Answer 3

您的配置没有问题。只是使用Configuration 对象引导休眠需要您在配置对象本身上设置 一些 配置属性。这些通过属性指定的配置将被忽略。

此外，使用配置对象引导休眠被认为是“传统”方式（as per official hibernate docs），建议使用newer way 引导休眠，如下所示。

    public static void main(String[] args) {
        Transaction tx = null;

        StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder()
                .configure() // using "hibernate.cfg.xml"
                .build();
        Metadata metadata = new MetadataSources(standardRegistry).buildMetadata();
        try (
                SessionFactory sessionFactory = metadata.getSessionFactoryBuilder().build();
                Session session = sessionFactory.openSession();) {
            tx = session.beginTransaction();

            Cake cake = new Cake("Molten Chocolate Cake", "chocolate", 1);
            session.save(cake);

            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            if (tx != null) {
                tx.rollback();
            }
        }
    }

这将选择在hibernate.cfg.xml 文件中指定为休眠属性的物理命名策略。