这是hibernate.cfg.xml中的内容

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <property name="hibernate.ejb.naming_strategy">org.hibernate.cfg.ImprovedNamingStrategy</property>
        <property name="hibernate.connection.charSet">UTF-8</property> 
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="connection.pool_size">1</property>
        <property name="show_sql">true</property>
        <property name="hibernate.use_outer_join">true</property>
        <property name="current_session_context_class">thread</property>
    </session-factory>
</hibernate-configuration>

另外，我正在动态覆盖某些属性…

 Configuration config = new Configuration().configure("path_to_hibernate.cfg.xml");
 config.setProperty("hibernate.connection.url", System.getenv("HEROKU_POSTGRESQL_MYCOLOR_URL"));
 config.setProperty("hibernate.connection.username", "***");
 config.setProperty("hibernate.connection.password", "***");

但是，当我运行它时，出现此错误…

ERROR: No suitable driver found for postgres://*******:*********@ec2-23-21-85-197.compute-1.amazonaws.com:5432/d9i5vp******o7te

如何配置属性，以便heroku找到postgres驱动程序？

（我是hibernate和Heroku的新手，因此非常感谢您的帮助：）