Question

public class ContactManager {

    public static void main(String[] args) {
        // loads configuration and creates a session factory
        Configuration configuration = new Configuration().configure();
        ServiceRegistryBuilder registry = new ServiceRegistryBuilder();
        registry.applySettings(configuration.getProperties());
        ServiceRegistry serviceRegistry = registry.buildServiceRegistry();
        SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);

        // opens a new session from the session factory
        Session session = sessionFactory.openSession();
        session.beginTransaction();

        // persists two new Contact objects 
        Contact contact1 = new Contact("Nam", "hainatu@gmail.com", "Vietnam", "0904277091");
        session.persist(contact1);

        Contact contact2 = new Contact("Bill", "bill@gmail.com", "USA", "18001900");
        Serializable id = session.save(contact2);
        System.out.println("created id: " + id);

        // loads a new object from database
        Contact contact3 = (Contact) session.get(Contact.class, new Integer(1));
        if (contact3 == null) {
            System.out.println("There is no Contact object with id=1");
        } else {
            System.out.println("Contact3's name: " + contact3.getName());
        }

        // loads an object which is assumed exists
        Contact contact4 = (Contact) session.load(Contact.class, new Integer(1));
        System.out.println("Contact4's name: " + contact4.getName());
 // updates a loaded instance of a Contact object
        Contact contact5 = (Contact) session.load(Contact.class, new Integer(2));
        contact5.setEmail("info1@company.com");
        contact5.setTelephone("1234567890");
        session.update(contact5);

错误：

Hibernate: select max(CONTACT_ID) from CONTACT
created id: 2
Contact3's name: Nam
Contact4's name: Nam
Hibernate: select contact0_.CONTACT_ID as CONTACT1_0_0_, contact0_.NAME as NAME0_0_, contact0_.email as email0_0_, contact0_.address as address0_0_, contact0_.telephone as telephone0_0_ from CONTACT contact0_ where contact0_.CONTACT_ID=?
Exception in thread "main" org.hibernate.ObjectNotFoundException: No row with the given identifier exists: [com.mycompany.Contact#8]

Answer 1

使用id方法中session.save(contact2)返回的load()将其从数据库中恢复。它应该工作。

Contact contact5 = (Contact) session.load(Contact.class, id);

线程“main”中的异常org.hibernate.ObjectNotFoundException：不存在具有给定标识符的行：[com.mycompany.Contact＃8]

1 个答案: