没有Spring和没有XML的最小JPA示例

<dependencies>
    <dependency>
        <groupId>javax.persistence</groupId>
        <artifactId>javax.persistence-api</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.0.Final</version>
    </dependency>
    <!-- 其他依赖 -->
</dependencies>

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "User")
public class User {
    @Id
    private Long id;
    private String name;

    // 构造函数、Getter和Setter方法
}

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class JpaExample {
    private static final String PERSISTENCE_UNIT_NAME = "example";

    public static EntityManagerFactory getEntityManagerFactory() {
        return Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
    }

    // 其他方法
}

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Query;
import java.util.List;

public class JpaExample {
    // 省略上述代码

    public static void main(String[] args) {
        EntityManagerFactory entityManagerFactory = getEntityManagerFactory();
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        EntityTransaction transaction = entityManager.getTransaction();

        try {
            transaction.begin();

            // 插入数据
            User user = new User();
            user.setId(1L);
            user.setName("John Doe");
            entityManager.persist(user);

            // 查询所有数据
            Query query = entityManager.createQuery("SELECT u FROM User u");
            List<User> userList = query.getResultList();
            for (User u : userList) {
                System.out.println(u.getId() + ": " + u.getName());
            }

            transaction.commit();
        } catch (Exception e) {
            if (transaction != null && transaction.isActive()) {
                transaction.rollback();
            }
            e.printStackTrace();
        } finally {
            entityManager.close();
            entityManagerFactory.close();
        }
    }
}