JPA Persist: DB-Tabelle wird überschrieben

[brauni18]

Hallo =)

also ich bin ziemlich neu in EE, deswegen ist das wahrscheinlich eine Anfängerfrage.


ich hab folgende eine Entity-Class:

import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;

/**
 *
 * @author User
 */
@Entity
@Table(name = "user")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "User.findAll", query = "SELECT u FROM User u"),
    @NamedQuery(name = "User.findById", query = "SELECT u FROM User u WHERE u.id = :id"),
    @NamedQuery(name = "User.findByName", query = "SELECT u FROM User u WHERE u.name = :name"),
    @NamedQuery(name = "User.findByLogin", query = "SELECT u FROM User u WHERE u.login = :login"),
    @NamedQuery(name = "User.findByPassword", query = "SELECT u FROM User u WHERE u.password = :password")})
public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Basic(optional = false)
    @NotNull
    @Column(name = "ID")
    private Integer id;
    @Size(max = 50)
    @Column(name = "name")
    private String name;
    @Size(max = 50)
    @Column(name = "login")
    private String login;
    @Size(max = 100)
    @Column(name = "password")
    private String password;

    public User() {
    }
    
    public User(String name, String login, String password){
        this.name=name;
        this.login=login;
        this.password=password;
    }
    
    public User(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof User)) {
            return false;
        }
        User other = (User) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.test.User[ id=" + id + " ]";
    }
    
}

(vielleicht ist es wichtig: die ID-Spalte in meiner Tabelle ist der Primery key und wird automatisch incrementiert)

Und das ist mein aufrufendes Servlet, bzw. die Process-Request-Methode:

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet login</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet login at " + request.getContextPath() + "</h1>");

            EntityManagerFactory emf = Persistence.createEntityManagerFactory("NewPU");
            EntityManager em = emf.createEntityManager();
            em.getTransaction().begin();
            User u = new User("blabla", "bla", "blapass");
            em.persist(u);
            em.getTransaction().commit();

            List list = em.createQuery(
                    "select u from User u where u.name = :name").setParameter("name", u.getName()).getResultList();
            
            out.println("<b>Total Users: " + list.size() + "</b><br>");
            for (int i = 0; i < list.size(); i++) {
                out.println((User) list.get(i) + "<br>");
            }

            out.println("</body>");
            out.println("</html>");

        } finally {
            out.close();
        }
    }

Das Problem ist, dass bei jedem aufruf des Servlets alle Einträge in der DB-Tabelle überschrieben mit der einen neuen Entity-Instanz die ich persistiere.

Kann mir jemand helfen?

 

[maki]

Die Antwort steht in deiner persistence.xml 😉

 

[brauni18]

Die Antwort steht in deiner persistence.xml 😉

meinst du die Table Generation Strategy?

...habs probiert...krieg ich nicht hin?!
ich hab EclipseLink als Persistence Provider...ist das wichtig?