Question

我已经创建了一个数据库连接和一些实体，现在我正在尝试测试我的数据库的功能。我有一个User实体类，它有一个唯一的用户名和一些其他信息。现在我正在尝试简单地创建一个新的用户和个人资料并将它们映射在一起，然后坚持下去。当我测试代码时，它成功运行，但DB没有更新。这就是我所拥有的：

package servlets;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceUnit;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.transaction.UserTransaction;

import entities.Profile;
import entities.User;


@WebServlet("/NewUser")
public class NewUser extends HttpServlet {

    @Resource
    UserTransaction utx;
    @PersistenceUnit
    EntityManagerFactory emf;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String email = request.getParameter("email");
        String firstname = request.getParameter("firstname");
        String lastname = request.getParameter("lastname");
        String phone = request.getParameter("phone");
        String address1 = request.getParameter("address1");
        String address2 = request.getParameter("address2");


        try {
            utx.begin();
            EntityManager em = emf.createEntityManager();

            //create User & Profile
            User u = new User();
            u.setUsername(username);
            Profile p = new Profile();
            p.setUser(username);

            //add email to profile's list
            List<String> emails = new ArrayList<String>();
            emails.add(email);
            p.setEmails(emails);

            //assign the profile to the user
            u.setProfile(p);

            //persist user to the database
            em.persist(u);
            utx.commit();

            em.close();
            emf.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        response.sendRedirect("index.jsp");
    }
}

我做错了什么或是应用程序中的其他地方的问题？

编辑：我发现以下错误：异常说明：无法从驱动程序[null]，用户[null]和URL [null]获取连接。验证您是否已设置预期的驱动程序类和URL。检查您的登录名，persistence.xml或sessions.xml资源。应将jdbc.driver属性设置为与数据库平台兼容的类

我不知道该怎么做错误，但是...我已经检查了我的数据库连接，一切似乎都是有序的。：/

我的persistence.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="myPersistenceUnit" >
    <jta-data-source>jdbc/mydatasource</jta-data-source>
        <class>entities.User</class>
        <class>entities.Profile</class>
        <class>entities.Message</class>
        <class>entities.Image</class>
        <properties>
            <property name="eclipselink.ddl-generation" value="create-tables"/>
            <property name="eclipselink.ddl-generation.output-mode" value="both"/>
        </properties>
    </persistence-unit>
</persistence>

Answer 1

我从不使用容器管理的事务，但你的persistence.xml至少有。

 <persistence-unit name="myPersistenceUnit" transaction-type="JTA">

将新实体保留到现有数据库JPA

1 个答案: