如果我需要获取整数来运行查询，JSF Converter 的正确实现是什么？ （我应该使用其他接口吗）

Question

您好，这是我的代码：

List.xhmtl

<h:selectOneMenu value="#{produtosController.items}">
    <f:selectItems value="#{produtosController.itemsAvailableSelectOne}"/>
</h:selectOneMenu>
<h:commandButton action="#{produtosController.createByCodigos}" value="Buscar" />

我的控制器类，带有内部转换器实现

@ManagedBean (name="produtosController")
@SessionScoped
public class ProdutosController {

    private Produtos current;
    private DataModel items = null;
    @EJB private controladores.ProdutosFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public ProdutosController() {
    }

    public Produtos getSelected() {
        if (current == null) {
            current = new Produtos();
            selectedItemIndex = -1;
        }
        return current;
    }

    private ProdutosFacade getFacade() {
        return ejbFacade;
    }

    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {

                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem()+getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new Produtos();
        selectedItemIndex = -1;
        return "Create";
    }

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }
    public String createByMarcas() {
        items = new ListDataModel(ejbFacade.findByMarcas(current.getIdMarca()));
        updateCurrentItem();
        return "List";
    }

    public String createByModelos() {
        items = new ListDataModel(ejbFacade.findByModelos(current.getIdModelo()));
        updateCurrentItem();
        return "List";
    }

    public String createByCodigos(){
        items = new ListDataModel(ejbFacade.findByCodigo(current.getCodigo()));
        updateCurrentItem();
        return "List";
    }

    public String prepareEdit() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count-1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex+1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;
    }

    private void recreateModel() {
        items = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    @FacesConverter(forClass=Produtos.class)
    public static class ProdutosControllerConverter  implements Converter{

        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            ProdutosController controller = (ProdutosController)facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "produtosController");
            return controller.ejbFacade.find(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.decode(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuffer sb = new StringBuffer();
            sb.append(value);
            return sb.toString();
        }

        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Produtos) {
                Produtos o = (Produtos) object;
                return getStringKey(o.getCodigo());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: "+ProdutosController.class.getName());
            }
        }

    }

}

和我的 EJB

@Entity
@ViewScoped
@Table(name = "produtos")
@NamedQueries({
    @NamedQuery(name = "Produtos.findAll", query = "SELECT p FROM Produtos p"),
    @NamedQuery(name = "Produtos.findById", query = "SELECT p FROM Produtos p WHERE p.id = :id"),
    @NamedQuery(name = "Produtos.findByCodigo", query = "SELECT p FROM Produtos p WHERE p.codigo = :codigo"),
    @NamedQuery(name = "Produtos.findByDescripcion", query = "SELECT p FROM Produtos p WHERE p.descripcion = :descripcion"),
    @NamedQuery(name = "Produtos.findByImagen", query = "SELECT p FROM Produtos p WHERE p.imagen = :imagen"),
    @NamedQuery(name = "Produtos.findByMarcas", query="SELECT m FROM Produtos m WHERE m.idMarca.id = :idMarca"),
    @NamedQuery(name = "Produtos.findByModelos", query="SELECT m FROM Produtos m WHERE m.idModelo.id = :idModelo")})
public class Produtos implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Column(name = "codigo")
    private Integer codigo;
    @Column(name = "descripcion")
    private String descripcion;
    @Column(name = "imagen")
    private String imagen;
    @JoinColumn(name = "id_modelo", referencedColumnName = "id")
    @ManyToOne(optional = false)
    private Modelos idModelo;
    @JoinColumn(name = "id_marca", referencedColumnName = "id")
    @ManyToOne(optional = false)
    private Marcas idMarca;

    public Produtos() {
    }

    public Produtos(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

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

    public Integer getCodigo() {
        return codigo;
    }

    public void setCodigo(Integer codigo) {
        this.codigo = codigo;
    }

    public String getDescripcion() {
        return descripcion;
    }

    public void setDescripcion(String descripcion) {
        this.descripcion = descripcion;
    }

    public String getImagen() {
        return imagen;
    }

    public void setImagen(String imagen) {
        this.imagen = imagen;
    }

    public Modelos getIdModelo() {
        return idModelo;
    }

    public void setIdModelo(Modelos idModelo) {
        this.idModelo = idModelo;
    }

    public Marcas getIdMarca() {
        return idMarca;
    }

    public void setIdMarca(Marcas idMarca) {
        this.idMarca = idMarca;
    }

    @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 Produtos)) {
            return false;
        }
        Produtos other = (Produtos) 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 "" + codigo + "";
    }
}

Answer 1

抱歉，我没有仔细看你的代码。太多（乍一看）不相关的代码和几个过于本地化的名称只会让事情变得混乱。至少您的一个主要错误是您使用 DataModel 而不是实际的 Product 作为项目值。这毫无意义。

这是一个启动示例，代码应该是什么样子才能使下拉列表中的非标准类型完美地工作。

XHTML：

<h:form>
    <h:selectOneMenu value="#{bean.selectedProduct}">
        <f:selectItems value="#{bean.selectProducts}" />
    </h:selectOneMenu>
    <h:commandButton value="Submit" action="#{bean.submit}" />
</h:form>

Bean：

private Product selectedProduct; // +getter+setter
private List<SelectItem> selectProducts; // +getter

public Bean() {
    selectProducts = new ArrayList<SelectItem>();
    for (Product product : ejb.list()) {
        selectProducts.add(new SelectItem(product, product.getDescription()));
    }
}

public void submit() {
    System.out.println("Selected product: " + selectedProduct.getDescription());
}

ProductConverter：

public Object getAsObject(FacesContext context, UIComponent component, String value) {
    // Convert String to Integer and find Product by Integer ID.
    return ejb.find(Integer.valueOf(value));
}

public String getAsString(FacesContext context, UIComponent component, Object value) {
    // Convert Integer ID to String.
    return String.valueOf(((Product) value).getId());
}

---

或者，您还可以将 f:selectItems 与新的 JSF 2.0 var 属性一起使用，这样您就不需要转换 List< Product> 从 EJB 到 List：

XHTML：

<h:form>
    <h:selectOneMenu value="#{bean.selectedProduct}">
        <f:selectItems value="#{bean.selectProducts}" var="product" 
            itemValue="#{product}" itemLabel="#{product.description}" />
    </h:selectOneMenu>
    <h:commandButton value="Submit" action="#{bean.submit}" />
</h:form>

Bean：

private Product selectedProduct; // +getter+setter
private List<Product> selectProducts; // +getter

public Bean() {
    selectProducts = ejb.list();
}

public void submit() {
    System.out.println("Selected product: " + selectedProduct.getDescription());
}

这仍然需要相同的 ProductConverter。

---

另请参阅：

• 在 中使用对象h:selectOneMenu