我最近开始在应用程序中使用hibernate和c3p0作为ORM。但是，当我关闭会话工厂时，连接池不会自行关闭！这是我的应用程序中 唯一
可以进行会话操作的地方。

    StatelessSession session = null;
    Transaction transaction = null;


    try {
        session = sessionFactory.openStatelessSession();
        transaction = session.beginTransaction();

        List<Thingy> list = session.getNamedQuery("getAvailableThingy").list();

        transaction.commit();
        return list;

    } catch (Exception error) { 
        if (transaction != null) {
            transaction.rollback();
        }
        throw error;
    } finally {
        if (session != null) {
            session.close();
        }
    }

这是我的hibernate.cfg.xml配置文件

<?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.postgresql.Driver</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="javax.persistence.validation.mode">none</property>
        <property name="hibernate.connection.release_mode">after_transaction</property>

        <property name="hibernate.c3p0.minPoolSize">1</property>
        <property name="hibernate.c3p0.maxPoolSize">2</property>
        <property name="hibernate.c3p0.acquireIncrement">1</property>
        <property name="hibernate.c3p0.initialPoolSize">1</property>
        <property name="hibernate.c3p0.timeout">30</property>
        <property name="hibernate.c3p0.maxIdleTimeExcessConnections">5</property>
        <property name="hibernate.c3p0.idleConnectionTestPeriod">300</property>
    </session-factory>
</hibernate-configuration>

请注意，空闲连接非常短的原因是它是我尚未通过集成测试的唯一方法。他们经常打开和关闭会话工厂，因此我总是用尽所有连接。正如我们在项目开始时一样，从长远来看，我认为这不是一个非常可持续的策略。

需要注意的“有趣”是，尽管我将初始连接池设置为一个，但c3p0仍然尝试在启动时打开两个连接。我的猜测是某个隐藏的会话在某个地方不会关闭（但是在哪里？击败了我）。

那么，如何才能使那个烦人的连接池关闭呢？

附加信息：我如何创建和销毁会话工厂

import static com.google.common.base.Preconditions.*;

import javax.inject.Inject;
import javax.inject.Provider;
import javax.inject.Singleton;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.inject.Provides;


@Singleton 
public class PostgisConnection implements Provider<SessionFactory>, AutoCloseable {
    private final Logger logger = LoggerFactory.getLogger(getClass());
    private final ConnectionInfo connectionInfo;
    private SessionFactory sessionFactory = null;

    @Inject 
    public PostgisConnection(ConnectionInfo connectionInfo) {
        this.connectionInfo = connectionInfo;
    }

    public AutoCloseable open() {
        checkState(sessionFactory == null, "Connections to postgis are already open");

        logger.info("Creating sessionFactory for connection to postgis: {}", connectionInfo.getJdbcUrl());
        sessionFactory = newPostgisSessionFactory(connectionInfo);

        return this;
    }

    @Override
    public void close() throws Exception {
        try {
            if (sessionFactory != null) {
                logger.info("Closing sessionFactory for postgis: {}", connectionInfo.getJdbcUrl());
                sessionFactory.close();
                checkState(sessionFactory.isClosed(), "Session factory should be closed at this point");
            }
        } catch (Exception error) {
            logger.error("Error closing SessionFactory", error);
        }
    }

    @Provides 
    public SessionFactory get() {
        return sessionFactory;
    }

    public static SessionFactory newPostgisSessionFactory(ConnectionInfo connectionInfo) {
        Configuration configuration = configurationWith(connectionInfo);
        return configuration.buildSessionFactory(registryFrom(configuration));
    }

    private static Configuration configurationWith(ConnectionInfo connectionInfo) {
        Configuration configuration = new Configuration();
        setConnectionInfo(connectionInfo, configuration);
        configuration.addURL(PostgisConnection.class.getResource("mapping.hbm.xml"));
        configuration.configure(PostgisConnection.class.getResource("hibernate.cfg.xml"));

        return configuration;
    }

    private static void setConnectionInfo(ConnectionInfo connectionInfo, Configuration configuration) {
        configuration.setProperty("hibernate.connection.url", connectionInfo.getJdbcUrl());
        configuration.setProperty("hibernate.connection.username", connectionInfo.getUsername());
        configuration.setProperty("hibernate.connection.password", connectionInfo.getPassword());
    }

    private static ServiceRegistry registryFrom(Configuration configuration) {
        return new ServiceRegistryBuilder()
                .applySettings(configuration.getProperties())
                .buildServiceRegistry();
    }

}

• Hibernate版本：4.1.10.Final
• C3p0版本：0.9.1.2