java – 使用jpa / hibernate进行实体更新的问题

@Entity
@Table(name = "PAGINA")
@NamedQueries({@NamedQuery(name = "Pagina.findAll",query = "SELECT p FROM Pagina p"),@NamedQuery(name = "Pagina.findHashByURL",query= "SELECT p.chash FROM Pagina p WHERE p.url = :url"),@NamedQuery(name = "Pagina.findTimestampByURL",query= "SELECT p.timestamp FROM Pagina p WHERE p.url = :url"),@NamedQuery(name = "Pagina.findByUrl",query = "SELECT p FROM Pagina p WHERE p.url = :url"),@NamedQuery(name = "Pagina.findByProfondita",query = "SELECT p FROM Pagina p WHERE p.profondita = :profondita"),@NamedQuery(name = "Pagina.findByIntervallo",query = "SELECT p FROM Pagina p WHERE p.intervallo = :intervallo"),@NamedQuery(name = "Pagina.findByTimestamp",query = "SELECT p FROM Pagina p WHERE p.timestamp = :timestamp"),@NamedQuery(name="Pagina.findAllURL",query="SELECT p.url FROM Pagina p"),@NamedQuery(name="Pagina.findDelayByURL",query="SELECT p.intervallo FROM Pagina p WHERE p.url = :url"),@NamedQuery(name = "Pagina.findByUpdated",query = "SELECT p FROM Pagina p WHERE p.updated = :updated")})
public class Pagina implements Serializable,Delayed{
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @Column(name = "URL")
    private String url;
    @Column(name = "PROFONDITA")
    private Integer profondita;
    @Column(name = "INTERVALLO")
    private Integer intervallo;
    @Lob
    @Column(name = "CHASH")
    private String chash;
    @Column(name = "TIMESTAMP")
    private Integer timestamp;
    @Column(name = "UPDATED")
    private Boolean updated;


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在另一个类中,我使用包含在实体上工作的方法的类中定义的方法来检索存储在数据库(mysql)中的对象.此方法使用查询“findAll”.方法的代码如下：

public List<Pagina> findAll(){
EntityManagerFactory emf = javax.persistence.Persistence.createEntityManagerFactory("CrawlerPU");
        EntityManager em = emf.createEntityManager();  
List o = (List) em.createNamedQuery("Pagina.findAll").getResultList();
        return o;
    }

我正在使用此方法,您可以在代码中看到：

PaginaMethods p = new PaginaMethods();

        List<Pagina> l = p.findAll();
   while (it.hasNext()) {
            Pagina s = (Pagina) it.next();
            s.setUpdated(Boolean.TRUE);

如果我观看数据库,则此操作后没有任何变化.我的persistence.xml有条目“”
你能帮助我吗？我不知道如何解决这个问题……如果需要,我可以改变一些事情.