java - Jpa 合并抛出 StaleObjectStateException？

Question

当我尝试创建四个客户时，有代码。1.将Customer1,2写入数据库2. 合并Customer3(具有相同的id，例如1)3.合并Customer4(再次具有相同的id)我想创建同一实体的任何版本

所以，

public static void main(String[] args) {
        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("Info");
        EntityManager entityManager = entityManagerFactory.createEntityManager();

        Customer customer1 = new Customer("1", "Vladislav");
        Customer customer2 = new Customer("2", "Maria");
        Customer customer3 = new Customer("1", "Ekaterina");
        Customer customer4 = new Customer("1", "Helen");

        entityManager.getTransaction().begin();
        entityManager.persist(customer1);
        entityManager.persist(customer2);
        entityManager.getTransaction().commit();

        entityManager.getTransaction().begin();
        entityManager.merge(customer3);
        entityManager.getTransaction().commit();

        entityManager.getTransaction().begin();
        entityManager.merge(customer4);
        entityManager.getTransaction().commit();

        //get versions here:
        entityManager = entityManagerFactory.createEntityManager();
        AuditReader auditReader = AuditReaderFactory.get(entityManager);
        List<Number> versions = auditReader.getRevisions(Customer.class, "1");
        System.out.println("========");
        System.out.println(Arrays.toString(versions.toArray()));

        entityManager.close();
        entityManagerFactory.close();
    }

客户实体:

package entity;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import org.hibernate.envers.Audited;

import javax.persistence.*;


@Getter
@Setter
@NoArgsConstructor
@Entity
@Audited
public class Customer {
    @Id
    @Column(length = 100, nullable = false)
    private String id;
    private String name;

    @Version
    int version;

    public Customer(String id, String name) {
        this.id = id;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", version=" + version +
                '}';
    }
}

当我仅保留客户 1,2 并合并客户 3 时 - 一切正常。

但是在我添加与 customer4 实体的合并时 - 出现错误消息 -

线程“main”中出现异常 javax.persistence.OptimisticLockException:行已被另一个事务更新或删除(或未保存值映射不正确):[entity.Customer#1]导致:org.hibernate.StaleObjectStateException:行已被另一个事务更新或删除(或未保存值映射不正确):[entity.Customer#1] ... 2 更多

为什么我每次都无法合并？

Answer 1

您只能将客户与具有最新版本的实例合并。

customer1 具有版本=0

id = '1'的当前版本现在为 0

customer3 具有 version=0，因此可以合并，合并后 version=1。

id = '1'的当前版本现在是 1

customer4 具有 version=0，因此无法再进行合并。