EntityManager没有名为Postgres的EntityManager的持久提供商。 Maven项目

Question

我刚开始使用JPA，由于某种原因，我遇到了这个错误：

2022年5月18日上午10:47:45 javax.persistence.spi.persistenceProviderResolverholder $ defaultPersistenceProviderResolver 日志警告：javax.persistence.spi ::找不到有效的提供者。 线程“ main” javax.persistence.persistenceException中的异常：否 EntityManager的持久性提供商名为Postgres at javax.persistence.persistence.createentitymanagerfactory（persistence.java:86） 在 javax.persistence.persistence.createentitymanagerfactory（persistence.java:55） 在main.stesjpa（main.java：17）上的main.main（main.java:64）

持久单位名称与代码中的单位匹配。这是证明：

public static void testJPA() {
        EntityManagerFactory emf =
                Persistence.createEntityManagerFactory("postgres");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        Continent continent = new modelbase.Continent("1","Europe");
        em.persist(continent);

        Continent c = (Continent)em.createQuery(
                        "select e from ContinentEntity e where e.name='Europe'")
                .getSingleResult();
        c.setName("Africa");
        em.getTransaction().commit();
        em.close();
        emf.close();
    }

这是persistance.xml：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persistence xmlns="https://jakarta.ee/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="https://jakarta.ee/xml/ns/persistence https://jakarta.ee/xml/ns/persistence/persistence_3_0.xsd"
             version="3.0">
  <persistence-unit name="postgres"
              transaction-type="RESOURCE_LOCAL">
  <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
  <exclude-unlisted-classes>false</exclude-unlisted-classes>
  <properties>
    <property name="javax.persistence.jdbc.driver"
              value="org.postgresql.Driver"/>
    <property name="javax.persistence.jdbc.url"
              value="jdbc:postgresql://localhost:5432/postgres"/>
    <property name="javax.persistence.jdbc.user" value="postgres"/>
    <property name="javax.persistence.jdbc.password"
              value="4563"/>
  </properties>
  </persistence-unit>
</persistence>

现在试图过去2个小时以来要克服此错误，似乎无法弄清楚原因。 这也是pom.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>LAB9</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.3.4</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>eclipselink</artifactId>
            <version>3.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>javax.persistence</artifactId>
            <version>2.2.1</version>
        </dependency>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.1.Final</version>
        </dependency>
    </dependencies>
</project>

Answer 1

您使用基于Jakarta XSD（3.0）的最新版本的持久性XML，但使用Javax.persistence连接到数据库。

您必须使用Juste：
org.hibernate.jpa.hibernatepersistenceProvider

<property name="jakarta.persistence.jdbc.driver" value="Driver ..."/>
<property name="jakarta.persistence.jdbc.url" value="jdbc:..."/>
<property name="jakarta.persistence.jdbc.user" value="user"/>
<property name="jakarta.persistence.jdbc.password" value="psw"/>  

，并在your pom.xml中包含folloin文物

<dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>eclipselink</artifactId>
    <version>3.0.2</version>
 </dependency>

-- Or


 <dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core-jakarta</artifactId>
    <version>5.6.9.Final</version>
 </dependency>