使用Eclipse的Postgres的基本独立JPA示例

Question

我一直在尝试使用Eclipse IDE获得一个非常基本的独立JPA示例来与Postgres一起使用.

我有一个persistance.xml定义,看起来像这样.

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    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_1_0.xsd">
    <persistence-unit name="sample" transaction-type="RESOURCE_LOCAL">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>package.class</class>
        <exclude-unlisted-classes>false</exclude-unlisted-classes>
        <properties>
            <property name="eclipselink.logging.level" value="INFO" />
            <property name="eclipselink.jdbc.driver" value="org.postgresql.Driver" />
            <property name="eclipselink.jdbc.url"
                value="jdbc:postgresql://localhost:5432/sample" />
            <property name="eclipselink.jdbc.user" value="scott" />
            <property name="eclipselink.jdbc.password" value="tiger" />
        </properties>
    </persistence-unit>
</persistence>

该文件位于src/main/resources/META-INF文件夹中.我已将src/main/resources文件夹包含在eclipse中的源目录中.我有一个简单的实体定义名为User.当我尝试创建该实体时

EntityManagerFactory entityManagerFactory 
         = Persistence.createEntityManagerFactory("sample");
     EntityManager em = entityManagerFactory.createEntityManager();
     EntityTransaction tx = em.getTransaction();
     try {
         User user = new User();
         user.setEnabled(false);
         user.setEmailId("test@test.com");
         tx.begin();
          em.persist(user);
         tx.commit();
     } catch (Exception e) {
         em.getTransaction().rollback();
     } finally {
         em.close();
     }

我得到以下异常 - Exception in thread "main" javax.persistence.PersistenceException: No Persistence provider for EntityManager named sample

好像我的persistance.xml文件没有被选中.JPA框架在哪里加载persistance.xml文件？

Answer 1

这是一个愚蠢的错误.该文件需要调用persistence.xml而不是persistance.xml.