在 Hibernate 中使用 SessionFactory.getCurrentSession() 时获取 Connection 对象

Question

当使用 SessionFactory.getCurrentSession() 时，我试图在 Hibernate 中获取 Connection 对象。

源代码

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.internal.SessionImpl;

public class SOExample {
    public static void main(String[] args) throws SQLException {
        Configuration configuration = new Configuration();
        SessionFactory  sessionFactory = configuration.buildSessionFactory(new StandardServiceRegistryBuilder().configure().build());
        Session session = sessionFactory.getCurrentSession();
        Connection connection = ((SessionImpl) session).connection();
        // doing operation on connection object as per my requirement
        DatabaseMetaData databaseMetaData = connection.getMetaData();
        System.out.println(databaseMetaData.getDatabaseProductName());
    }
}

堆栈跟踪

Exception in thread "main" java.lang.ClassCastException: com.sun.proxy.$Proxy24 cannot be cast to org.hibernate.internal.SessionImpl
    at com.SOExample.main(SOExample.java:20)

getCurrentSession() 给出Session 的Proxy 对象，所以它不能将它转换为SessionImpl 那么还有什么其他方法可以得到Connection 对象。或者如何从代理对象SessionImpl。

---

我尝试了其他选项，但它显示getConnectionProvider() 方法未找到。

SessionFactoryImplementor sessionFactoryImplementation = (SessionFactoryImplementor) session.getSessionFactory();
ConnectionProvider connectionProvider = sessionFactoryImplementation.getConnectionProvider();
try {
    Connection connection = connectionProvider.getConnection();
} catch (SQLException e) {
    e.printStackTrace();
}

注意：我使用的是hibernate-core-5.0.5.Final.jar

Answer 1

在 Hibenate 5 中，我们需要做一些不同的事情（更多详情请查看https://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html）：

import java.sql.Connection;
import java.sql.SQLException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.Metadata;
import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
import org.hibernate.jdbc.Work;


public class Htest {

    public static void main(String ... args) throws SQLException {
        StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder()
                .configure("hibernate.cfg.xml")
                .build();

        Metadata metadata = new MetadataSources( standardRegistry )
                .addAnnotatedClass(TesEntity.class)
                .buildMetadata();

        SessionFactory sessionFactory = metadata.getSessionFactoryBuilder()
                .build();

        //one way to get connection version 5.0.2
        Connection c = sessionFactory.
                getSessionFactoryOptions().getServiceRegistry().
                getService(ConnectionProvider.class).getConnection();

        Session sess = null;
        try {
            sess = sessionFactory.getCurrentSession();
        } catch (org.hibernate.HibernateException he) {
            sess = sessionFactory.openSession();
        }


        //If you are using latest version 5.2.3 you can use this line below
        //Connection c =  ((SessionImpl)sess.getSession()).connection();
        System.out.println(c.getMetaData().getDatabaseProductName());

        //another way to get connection
        sess.doWork(new Work() {
            @Override
            public void execute(Connection connection) throws SQLException {
                //connection accessible here
                System.out.println(connection.getMetaData().getDatabaseProductName());
            }
        });
    }
}

如果你想测试代码，我对 derby db 的配置。

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>
        <property name="hibernate.connection.url">jdbc:derby://localhost:1527/mytest;create=fasle</property>
        <!-- <property name="connection.username"/> -->
        <!-- <property name="connection.password"/> -->

        <!-- DB schema will be updated if needed -->
        <!-- <property name="hbm2ddl.auto">update</property> -->
    </session-factory>
</hibernate-configuration>

此应用的输出：