Question

我正在使用JPA和Hibernate处理Swing应用程序。但每次我尝试调用以下代码来获取EntityManager

try {
    Class.forName("org.postgresql.Driver");
} catch (ClassNotFoundException e) {
    e.printStackTrace();
}
EntityManagerFactory emf = Persistence.createEntityManagerFactory("abcd");
EntityManager em = emf.createEntityManager();

我得到以下例外情况：

Caused by: javax.persistence.PersistenceException: No Persistence provider for EntityManager named abcd: Provider named org.hibernate.jpa.HibernatePersistenceProvider threw unexpected exception at create EntityManagerFactory: 
javax.persistence.PersistenceException
javax.persistence.PersistenceException: Unable to build entity manager factory

和

Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set

persistence.xml的路径为my.jar/meta-inf/persistence.xml

 <?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="abcd" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <property name="hibernate.connection.url" value="xxx"/>
            <property name="hibernate.connection.password" value="xxx"/>
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
            <property name="hibernate.connection.user" value="xxx"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
        </properties>
    </persistence-unit>
</persistence>

依赖关系：

除junit之外的所有依赖项都在类路径中

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.8</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>javax.persistence</groupId>
        <artifactId>persistence-api</artifactId>
        <version>1.0.2</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.10.Final</version>
        <scope>compile</scope>
    </dependency>

Answer 1

看来，它无法找到您的persistence.xml文件。 persistence.xml文件的正确文件夹为META-INF，而非meta-inf。

Hibernate，JPA，没有为EntityManager命名的持久性提供程序

1 个答案: