selectOneMenu转换器

Question

嗨，我正在研究Primfaces页面上的每一个身体，我必须让selectOneMenu从dataBase中获取项目，所以我试着这样做但我仍然对转换器有问题

所以我的源代码如下：

selectOneMenu：

<p:selectOneMenu id="devises" required="true" value="#{pret.devise}" effect="fade" converter="devise">  
    <f:selectItem itemLabel="Select One" itemValue="" />  
    <f:selectItems value="#{devise.listDevise()}" var="devise" itemLabel="#{devise.nomDevise}" itemValue="#{devise}"/>  
</p:selectOneMenu>

转换器代码：

@FacesConverter(value = "devise")
public class DeviseConverter implements Converter{  

    public static List<Devise> devises = Devise.listDevise();  

    public Object getAsObject(FacesContext facesContext, UIComponent component, String submittedValue) {  
        if (submittedValue.trim().equals("")) {  
            return null;  
        } else {  
            try {  
                int idDevise = Integer.parseInt(submittedValue);
                for (Devise p : devises) {  
                    if (p.getIdDevise()== idDevise) {  
                        return p;  
                    }  
                }
            } catch(NumberFormatException exception) {  
                throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Conversion Error", "Not a valid Devise"));  
            }  
        }
        return null;  
    }  

    public String getAsString(FacesContext facesContext, UIComponent component, Object value) {  
        if (value == null || value.equals("")) {  
            return "";  
        } else {  
            return String.valueOf(((Devise) value).getIdDevise());  
        }  
    }
}

错误代码是：“设计：验证错误：值无效”

Answer 1

您的对象Devise需要包含equals()和hashCode()方法。

此外，你可以使用这个generic converter，这将适用于所有类型的对象，你不需要为所有选择列表编写转换器。

import java.util.Map;
import java.util.Map.Entry;
import java.util.UUID;
import java.util.WeakHashMap;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;

@FacesConverter(value = "entityConverter")
public class EntityConverter implements Converter {

    private static Map<Object, String> entities = new WeakHashMap<Object, String>();

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object entity) {
        synchronized (entities) {
            if (!entities.containsKey(entity)) {
                String uuid = UUID.randomUUID().toString();
                entities.put(entity, uuid);
                return uuid;
            } else {
                return entities.get(entity);
            }
        }
    }

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String uuid) {
        for (Entry<Object, String> entry : entities.entrySet()) {
            if (entry.getValue().equals(uuid)) {
                return entry.getKey();
            }
        }
        return null;
    }

}