Question

大家好我有jsf托管bean和@PersistenceUnit的问题。我正在使用这个转换器

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.faces.convert.FacesConverter;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import mn.bsoft.crasmonclient.model.Customer;

/**
 *
 * @author D
 */
@ManagedBean
@RequestScoped
@FacesConverter(value="convertToConverter")
public class ConvertToCustomer  implements Converter{
    @PersistenceUnit(unitName = "CrasmonClientPU")
    private EntityManagerFactory entityManagerFactory;
    private EntityManager em;

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        try {
            em = entityManagerFactory.createEntityManager();
            Object ret = em.find(Customer.class, new Integer(value));
            return ret;
        } catch (ConverterException e) {
            System.out.println(e.getFacesMessage());
        }  
        return null;
    }

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) {
        try {
            Customer pa = (Customer) value;
            return String.valueOf(pa.getCustomerId());

        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        return null;
    }

}

我在EntityManagerFactory上得到了空指针异常。在我的faces-config文件中，我有：

<converter>
<converter-id>convertToCustomer</converter-id>
<converter-class>crasmonclient.converter.ConvertToCustomer</converter-class>
</converter>

我错过了什么吗？我不明白为什么得到空指针。

Answer 1

确保在WAR项目中有一个persistence.xml文件。此外，无法同时使用@ManagedBean和@FacesConverter。您需要删除@FacesConverter和<converter>以避免混淆，并将转换器专门用作托管bean，如下所示：

<h:inputText converter="#{convertToCustomer} />

此外，为什么不直接注射@PersistenceContext：

@PersistenceContext
EntityManager em;

管理豆转换器注入

1 个答案: