Java eclipselink持久性错误和格式不正确的xml文档

在eclipselink JPA示例中获取此错误。我正在尝试建立一个简单的JPA类。它抱怨xml文档格式不好，但我看不出有任何问题。请告诉我任何指示。谢谢

主要课程为：

package de.vogella.jpa.simple.main;

import java.util.List;

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

import de.vogella.jpa.simple.model.Todo;

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

  public static void main(String[] args) {
    factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
    EntityManager em = factory.createEntityManager();
    // read the existing entries and write to console
    Query q = em.createQuery("select t from Todo t");
    List<Todo> todoList = q.getResultList();
    for (Todo todo : todoList) {
      System.out.println(todo);
    }
    System.out.println("Size: " + todoList.size());

    // create new todo
    em.getTransaction().begin();
    Todo todo = new Todo();
    todo.setSummary("This is a test");
    todo.setDescription("This is a test");
    em.persist(todo);
    em.getTransaction().commit();

    em.close();
  }
} 

---

您是否缺少

org.eclipse.persistence.jpa.PersistenceProvider

它似乎在抱怨标签。移除它，看看它是否适合你。

<?xml version="1.0" encoding="UTF-8" ?>
<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"
  version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
  <persistence-unit name="todos" transaction-type="RESOURCE_LOCAL">
    <class>de.vogella.jpa.simple.model.Todo</class>
    <properties>
      <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver" />
      <property name="javax.persistence.jdbc.url"
        value="jdbc:derby:/home/vogella/databases/simpleDb;create=true" />
      <property name="javax.persistence.jdbc.user" value="test" />
      <property name="javax.persistence.jdbc.password" value="test" />

      <!-- EclipseLink should create the database schema automatically -->
      <property name="eclipselink.ddl-generation" value="create-tables" />
      <property name="eclipselink.ddl-generation.output-mode"
        value="database" />
    </properties>

  </persistence-unit>
</persistence> 

Exception in thread "main" Local Exception Stack: 
Exception [EclipseLink-30009] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while trying to load persistence unit at url: file:/C:/paul/oneView/java/de.vogella.jpa.simple/build/eclipse/
Internal Exception: Exception [EclipseLink-30004] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while processing persistence.xml from URL: file:/C:/paul/oneView/java/de.vogella.jpa.simple/build/eclipse/
Internal Exception: 
(1. The markup in the document preceding the root element must be well-formed.)
    at org.eclipse.persistence.exceptions.PersistenceUnitLoadingException.exceptionLoadingFromUrl(PersistenceUnitLoadingException.java:100)
    at org.eclipse.persistence.internal.jpa.deployment.PersistenceUnitProcessor.processPersistenceArchive(PersistenceUnitProcessor.java:597)
    at org.eclipse.persistence.internal.jpa.deployment.PersistenceUnitProcessor.getPersistenceUnits(PersistenceUnitProcessor.java:481)
    at org.eclipse.persistence.internal.jpa.deployment.JPAInitializer.findPersistenceUnitInfoInArchive(JPAInitializer.java:172)
    at org.eclipse.persistence.internal.jpa.deployment.JPAInitializer.findPersistenceUnitInfoInArchives(JPAInitializer.java:154)
    at org.eclipse.persistence.internal.jpa.deployment.JPAInitializer.findPersistenceUnitInfo(JPAInitializer.java:135)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:177)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:54)
    at de.vogella.jpa.simple.main.Main.main(Main.java:17)