Question

我正在尝试使用JPA和EclipseLink来持久保存元素。所以我创建了一个类来坚持

@Entity
public class Couple implements Serializable{
    private static final long serialVersionUID = 1L;
    @Column(name = "OBJECTID")
    private String objectID;
    @Column(name = "EPCNUMBER")
    private String epcNumber;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

等等。我创建了一个“使用”类：

public class Main {
  private static final String PERSISTENCE_UNIT_NAME = "MyPU";
  private static EntityManagerFactory factory;

  public static void main(String[] args) {
    factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
    EntityManager em = factory.createEntityManager();
    TypedQuery<Couple> q = em.createQuery("SELECT c FROM Couple c", Couple.class);
    List<Couple> couples = (List<Couple>) q.getResultList();

然后，我有以下persistence.xml：

<?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="MyPU">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>localJTA</jta-data-source>
        <class>fr.mypackage.com.Couple</class>
        <properties>
            <property name="eclipselink.ddl-generation" value="create-tables"/>
            <property name="eclipselink.ddl-generation.output-mode" value="database" />
            <property name="eclipselink.logging.level" value="INFO"/>
        </properties>
    </persistence-unit>
</persistence>

但是，即使我更改属性，我也会遇到同样的错误：

线程“main”中的异常javax.persistence.PersistenceException：没有名为MyPU的EntityManager的持久性提供程序（当调用factory = Persistence.createEntityManagerFactory（PERSISTENCE_UNIT_NAME）;）。

我是否对Ling xml和persistence unit做错了什么？我已将weel添加到classpath中：

javax.persistence.jar
javax.ejb.jar
eclipselink.jar
javax.persistence_1.0.0.jar
javax.persistence_2.0.4.v201112161009.jar
derby.jar

你可以帮帮我吗？谢谢！

Answer 1

在我的应用程序中，我遇到了这个问题，直到编译我的Netbeans项目。然后它奏效了。

找不到EntityManager的持久性提供程序

1 个答案: