我有一个名为“Pagina”的实体类,我想根据对实体所做的更改来更新数据库中的条目。这不起作用。我没有收到任何错误,但数据库没有更改。
@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,我使用类中定义的方法检索存储在数据库(mysql)中的对象,该类包含适用于实体的方法。此方法使用查询“findAll”。该方法的代码如下:
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;
}
我正在使用这种方法,正如您在代码中看到的那样:
PaginaMethods p = new PaginaMethods();
List<Pagina> l = p.findAll();
while (it.hasNext()) {
Pagina s = (Pagina) it.next();
s.setUpdated(Boolean.TRUE);
如果我观察数据库,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...如果需要的话我可以改变一些事情。