如何使用 JPA2 检查对象是否被锁定？

import javax.persistence.LockModeType;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class JPALockDemo {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("example-unit");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        MyEntity myEntity = em.find(MyEntity.class, 1, LockModeType.PESSIMISTIC_WRITE);
        // 检查对象是否被锁定
        if (myEntity != null) {
            System.out.println("对象已被锁定");
        } else {
            System.out.println("对象未被锁定");
        }
        em.getTransaction().commit();

        em.close();
        emf.close();
    }
}

import javax.persistence.LockModeType;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

public class JPALockDemo {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("example-unit");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        Query query = em.createQuery("SELECT e FROM MyEntity e WHERE e.id = :id");
        query.setParameter("id", 1);
        query.setLockMode(LockModeType.PESSIMISTIC_WRITE);
        MyEntity myEntity = query.getSingleResult();
        // 检查对象是否被锁定
        if (myEntity != null) {
            System.out.println("对象已被锁定");
        } else {
            System.out.println("对象未被锁定");
        }
        em.getTransaction().commit();

        em.close();
        emf.close();
    }
}