IllegalStateException：事务不活动

Question

java.lang.IllegalStateException：org.hibernate.transientPropertyValueException：object引用了一个未保存的瞬态实例-在刷新之前保存瞬态实例：entity.customer.passport->entity.passport

package entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

@Entity
public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;

    @OneToOne(cascade = { CascadeType.MERGE })
    @JoinColumn(name = "passport_id", unique = true)
    private Passport passport;

    public Customer() {
    }

    public Customer(String name, Passport passport) {
        this.setName(name);
        this.passport = passport;
    }

    public Passport getPassport() {
        return passport;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

 package client;

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

    import entity.Customer;
    import entity.Passport;

    public class OneToOneClient {

        public static void main(String[] args) {
            EntityManagerFactory emf = Persistence
                    .createEntityManagerFactory("jpa-training");
            EntityManager em = emf.createEntityManager();
            EntityTransaction txn = em.getTransaction();
            try {
                em.getTransaction().begin();
                //txn.begin();

                Passport passport = new Passport("99627317");
                Customer customer = new Customer("Customer1", passport);
                em.persist(customer);

                em.getTransaction().commit();
                //txn.commit();
            } catch (Exception e) {
                if (txn != null) {
                    txn.rollback();
                }
                e.printStackTrace();
            } finally {
                if (em != null) {
                    em.close();
                }
            }
        }

    }

注意：如果我在实体类中使用CascadeType.Persist，我可以在DB中插入另一行。

Answer 1

在客户之前保存passport，您就没事了。替代方案如您所提到的，使用cascade.persist。

Hibernate不会在没有被告知的情况下持久化其他实体。