如何使用 Maven 正確配置 Hibernate 項目？

Question

我剛剛開始使用 Hibernate 框架，並且正在使用 Gradle 用作自動化工具的教程 - 我從未使用過，所以我使用的是 Maven。

問題一開始就出現了。 在配置期間，一開始我想嘗試與數據庫的連接是否有效。

And I'm trying to figure out what I'm doing wrong, where am I making a configuration error, should I also have persistence.xml and hibernate.cfg.xml configured when using Maven?

For example, running application with only hibernate.cfg.xml file, during startup I'm getting error No Persistence provider for EntityManager named unit - a name unit, we can find in persistence.xml file: <persistence-unit name="unit" transaction-type="RESOURCE_LOCAL">.

App.java

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.*;


public class App {

private static EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("unit");

    public static void main(String[] args) {
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.getTransaction().commit();
        em.close();
    }
}

配置指南中使用persistence.xml文件

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
             http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
             version="2.1">
    <persistence-unit name="unit" transaction-type="RESOURCE_LOCAL">
        <properties>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver" />
            <property name="javax.persistence.jdbc.url"
                      value="jdbc:mysql://localhost/database?useUnicode=true&amp;serverTimezone=UTC" />
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="test" />

            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
        </properties>
    </persistence-unit>
</persistence>

我用Maven，想用hibernate.cfg.xml配置文件。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/database</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">test</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <mapping class="App" />

    </session-factory>
</hibernate-configuration>

當然，我還配置了一個pom.xml文件，其中包含依賴項和數據庫驅動程序。

<?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>TestEnvironment</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.6.4.Final</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

</project>

Answer 1

您需要在persistence.xml中定義持久性提供程序名稱：

<persistence-unit name="unit" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
    <properties>
        ...
    </properties>
</persistence-unit>