我刚接触javaee、jdbc和jpa。实际上，我已经通过jpa tools->generate entities from tables导入实体类，自动生成了实体类。
当我尝试运行此测试时：

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;

import model.User;

public class TestConnection {
    @PersistenceContext(unitName = "QuestionnaireEJB")
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("QuestionnaireEJB");
        EntityManager em = emf.createEntityManager();
        TestService testService = new TestService(em);

        //find an User by is id
        em.getTransaction().begin();
        User user = testService.findUser(1);
        System.out.println("found User:" + user);
    }
}

对于我的应用程序，我收到以下错误消息：
持久性提供程序正在尝试使用persistence.xml文件中的属性来解析数据源。必须在中指定java数据库连接（jdbc）驱动程序或数据源类名 openjpa.ConnectionDriverName 或者 javax.persistence.jdbc.driver 财产。
配置中提供了以下属性：“org.apache.openjpa.jdbc.conf。jdbcconfigurationimpl@a3ffd38e"

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.2" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd">
    <persistence-unit name="QuestionnaireEJB">
        <jta-data-source>QuestionnaireEJB</jta-data-source>
        <class>model.Accesstime</class>
        <class>model.Contain</class>
        <class>model.ContainPK</class>
        <class>model.Marketingquestion</class>
        <class>model.Offensiveword</class>
        <class>model.Product</class>
        <class>model.Questionnaire</class>
        <class>model.QuestionnairePK</class>
        <class>model.Review</class>
        <class>model.ReviewPK</class>
        <class>model.User</class>
    </persistence-unit>
</persistence>

这是我的 persistence.xml 文件位于 ejbModule/META-INF/persistence .