Hibernate 使用 hbm2ddl.auto=update 保留一些表，使用 hbm2ddl.auto=create 重新加载一些表答案

【问题标题】：Hibernate preserve some tables with hbm2ddl.auto=update, reload some tables with hbm2ddl.auto=createHibernate 使用 hbm2ddl.auto=update 保留一些表，使用 hbm2ddl.auto=create 重新加载一些表
【发布时间】：2017-02-24 16:31:39
【问题描述】：

顾名思义，我想问您是否可以在 hibernate 5.2.2 中对某些表使用 hbm2ddl.auto=update 而对其他表使用 hbm2ddl.auto=create。或者更好的是我可以在代码中明确定义现在我想创建新表而其他时候我只想更新？

HibernateConnector 的一个示例，我希望它如何工作：

public class HibernateConnector {

private static HibernateConnector me;
private Configuration cfg;
private SessionFactory sessionFactory;


private HibernateConnector(boolean db) throws HibernateException {
    if (db) {
        cfg = new Configuration();
        cfg.addAnnotatedClass(A.class);
        cfg.addAnnotatedClass(B.class);

        cfg.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
        cfg.setProperty("hibernate.connection.url", "jdbc:mysql:XXX");
        cfg.setProperty("hibernate.connection.username", "XXX");
        cfg.setProperty("hibernate.connection.password", "XYZ");
        cfg.setProperty("hibernate.show_sql", "true");
        cfg.setProperty("hibernate.hbm2ddl.auto", "create");
        sessionFactory = cfg.buildSessionFactory();
    } else {
        cfg = new Configuration();
        cfg.addAnnotatedClass(A.class);
        cfg.addAnnotatedClass(B.class);
        cfg.addAnnotatedClass(C.class);
        cfg.addAnnotatedClass(D.class);

        cfg.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
        cfg.setProperty("hibernate.connection.url", "jdbc:mysql://XXX");
        cfg.setProperty("hibernate.connection.username", "XYZ");
        cfg.setProperty("hibernate.connection.password", "XXX");
        cfg.setProperty("hibernate.show_sql", "true");
        cfg.setProperty("hibernate.hbm2ddl.auto", "update");
        sessionFactory = cfg.buildSessionFactory();
    }
}

public static synchronized HibernateConnector getInstance() throws HibernateException {
    if (me == null) {
        me = new HibernateConnector(false);
    }
    return me;
}

public static synchronized HibernateConnector getDBInstance() throws HibernateException {
    if (me == null) {
        me = new HibernateConnector(true);
    }
    return me;
}

public Session getSession() throws HibernateException {
    Session session = sessionFactory.openSession();
    if (!session.isConnected()) {
        this.reconnect();
    }
    return session;
}

private void reconnect() throws HibernateException {
    this.sessionFactory = cfg.buildSessionFactory();
}
}

谢谢你，祝你有美好的一天:)

【问题讨论】：

标签： java mysql hibernate hbm2ddl

【解决方案1】：

好的，所以我完全按照我在问题中提出的方式解决了这个问题。我使用简单的布尔标志来决定 HibernateConnector 的两个单独配置

private HibernateConnector(boolean db) throws HibernateException {
if (db) {
    cfg = new Configuration();
    cfg.addAnnotatedClass(A.class);
    cfg.addAnnotatedClass(B.class);

    cfg.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
    cfg.setProperty("hibernate.connection.url", "jdbc:mysql:XXX");
    cfg.setProperty("hibernate.connection.username", "XXX");
    cfg.setProperty("hibernate.connection.password", "XYZ");
    cfg.setProperty("hibernate.show_sql", "true");
    cfg.setProperty("hibernate.hbm2ddl.auto", "create");
    sessionFactory = cfg.buildSessionFactory();
} else {
    cfg = new Configuration();
    cfg.addAnnotatedClass(A.class);
    cfg.addAnnotatedClass(B.class);
    cfg.addAnnotatedClass(C.class);
    cfg.addAnnotatedClass(D.class);

    cfg.setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
    cfg.setProperty("hibernate.connection.url", "jdbc:mysql://XXX");
    cfg.setProperty("hibernate.connection.username", "XYZ");
    cfg.setProperty("hibernate.connection.password", "XXX");
    cfg.setProperty("hibernate.show_sql", "true");
    cfg.setProperty("hibernate.hbm2ddl.auto", "update");
    sessionFactory = cfg.buildSessionFactory();
}
}

我不完全确定这是最好的解决方案，但它确实有效。

【讨论】：