java - Hibernate重建DB表

Question

我有非常简单的 maven + hibernate 项目。

我想检索数据并使用命令“从产品中选择*”将其打印在控制台中。但每次我启动我的应用程序时，它都会重建数据库中的所有表，因此所有数据都被删除。

我应该怎么做才能在每次启动应用程序时重新构建表？

Main.java

public class Main {

static final Logger logger = LogManager.getLogger(Main.class);

public static void main(String[] args) {
    SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
    Session session = sessionFactory.openSession();
    List<Object> products = null;

    try {
        session.beginTransaction();

        SQLQuery query = session.createSQLQuery("select * from product");
        query.addEntity(Product.class);
        products = query.list();

        session.getTransaction().commit();
    } catch (Exception e) {
        session.getTransaction().rollback();
        e.printStackTrace();
    } finally {
        session.close();
        sessionFactory.close();
    }

    System.out.println("Hello");

    for (Iterator iterator = products.iterator(); iterator.hasNext(); ) {
        Product product = (Product) iterator.next();
        logger.info("Hello");
    }
}

hibernate.cfg.xml

<?xml version="1.0" encoding="utf-8"?> 
<!DOCTYPE hibernate-configuration PUBLIC 
"-//Hibernate/Hibernate Configuration DTD 3.0//EN" 
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/hibernate</property>
        <property name="hibernate.connection.username">postgres</property>
        <property name="hibernate.connection.password">****</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">create</property>
        <property name="hibernate.jdbc.lob.non_contextual_creation">true</property>

        <mapping class="models.User"/>
        <mapping class="models.Role"/>
        <mapping class="models.Product"/>
        <mapping class="models.ProductCategory"/>
        <mapping class="models.Order" />
    </session-factory>
</hibernate-configuration>

Answer 1

更改线路

 <property name="hbm2ddl.auto">create</property>

由

 <property name="hbm2ddl.auto">validate</property>

另请参阅https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#configurations-hbmddl