JPA 应用程序中的 Persistence.createEntityManagerFactory 错误

Question

我正在尝试创建 JPA 应用程序，但在测试它是否连接到 MySQL 服务器上的 MySQL 数据库时遇到问题。

这是错误：

    Exception in thread "main" java.lang.NoClassDefFoundError: org/dom4j/DocumentException
    at org.hibernate.ejb.Ejb3Configuration.<clinit>(Ejb3Configuration.java:153)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:57)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:78)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:54)
    at com.javawebtutor.JPATest.main(JPATest.java:13)
Caused by: java.lang.ClassNotFoundException: org.dom4j.DocumentException
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 5 more

这是在我的 persistence.xml 中：我也尝试过使用 hibernate 而不是 javax.persistence.jdbc

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" 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_1.xsd">
    <persistence-unit name="ProjekatV2" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <class>com.javawebtutor.Pacijent</class>
        <class>com.javawebtutor.Intervencija</class>
        <class>com.javawebtutor.BolnickaSoba</class>
        <class>com.javawebtutor.MedicinskiRadnik</class>
        <class>com.javawebtutor.Smena</class>
        <class>com.javawebtutor.Vozac</class>
        <class>com.javawebtutor.Vozilo</class>
        <class>com.javawebtutor.Zahtev</class>
        <properties>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:33060/infosys15495" />
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="root" />
        </properties>
    </persistence-unit>
</persistence>

这是我的测试课：

package com.javawebtutor;

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

public class JPATest {

    private static EntityManager em;

    public static void main(String[] args) {

        EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProjekatV2");
        em = emf.createEntityManager();

        createPacijent("Sladjana", "Nikolic", 1276948354);

        em.close();
        emf.close();
    }

    private static void createPacijent(String name, String surname, long brknji) {
        em.getTransaction().begin();
        Pacijent pac = new Pacijent(name, surname, brknji);
        em.persist(pac);
        em.getTransaction().commit();
    }

}

我得到了解决方案： 我不得不将 persistence.xml 标头更改为：

<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">

-谢谢约瑟夫！

Answer 1

抛出异常。看起来您需要向 hibernate 添加一些依赖库。因为找不到类 org.dom4j.DocumentException。我认为您应该尝试将 dom4j 安装到您的类路径