Question

我的问题是如何从'selectOneMenu'组件中的选择中获取价值。我使用POJO而不是String类型。我尝试在inputText中显示所选对象的name属性。我使用commandButton来刷新inputText中的值，如下面的代码所示。但问题是inputText中没有任何内容。我不确定是否需要使用转换器，但我尝试过它也没有用。

这是我的.jsp文件：

<p:selectOneMenu value="#{appointentBean.selectedSpecialization}">
    <f:selectItems value="#{appointentBean.specializationResult}" var="i" itemValue="#{i}" itemLabel="#{i.name}"/>
</p:selectOneMenu>

<p:commandButton value="Szukaj" >
    <p:ajax update="textid" />
</p:commandButton>

<p:inputText id="textid" value="#{appointentBean.selectedSpecialization.name}" />

appointmentBean：

@ManagedBean
@ViewScoped
@SessionScoped
public class appointentBean
{

private ArrayList<Specialization> specializationResult;
private Specialization selectedSpecialization;

  public ArrayList<Specialization> getSpecializationResult()
  {
    //Here retrievie objects list from database and it works

    return specializationResult;
  }

  public void setSpecializationResult(ArrayList<Specialization> result) {
    this.specializationResult = result;
  }

  public Specialization getSelectedSpecialization() {
    return selectedSpecialization;
  }

  public void setSelectedSpecialization(Specialization selectedSpecialization) {
    this.selectedSpecialization = selectedSpecialization;
  }
}

Specialization.java：

@Entity
@Table(name="Specializations")
public class Specialization
{
  @Id
  @GeneratedValue
  private int specialization_id;
  @Column(name="name")
  private String name;


  public int getSpecialization_id() {
    return specialization_id;
  }
  public void setSpecialization_id(int specialization_id) {
    this.specialization_id = specialization_id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}

更重要的是。如果我没有在列表上进行选择，则出现NullPointerExcetion。但是，当我做出选择时，我却没有。因此，在选择后设置对象。

Answer 1

像这样给你的Managed Bean命名

1.    @ManagedBean(name ="appointentBean")
2.    It should be in Session Scoped or View Scoped not in Both

您的代码在我的结尾完美运行。

我做了更改

ArrayList<Specialization> getSpecializationResult() like this:

 public ArrayList<Specialization> getSpecializationResult()
  {
    //Here retrievie objects list from database and it works
    specializationResult = new ArrayList<Specialization>();
    Specialization specialize= new Specialization();  
    specialize.setName("Vinayak");
    specialize.setSpecialization_id(1);
    specializationResult.add(specialize);
    return specializationResult;
  }

有效。所以，做出必要的改变并告诉我们。

编辑2

当我们当时处理POJO时，我们必须处理Converter。为什么自定义转换器的问题是您现在想要问的问题。请参阅Custom Converter

以下是创建自定义转换器的步骤 1.通过实现javax.faces.convert.Converter接口创建转换器类。 2.重写getAsObject（）和getAsString（）方法。 3.使用javax.annotation中的@FacesConverter注释指定唯一的转换器ID。

首先，我为您的专业化类

创建了一个POJOConverter类

package primefaces1;

import java.util.ArrayList;
import java.util.List;

import javax.faces.application.FacesMessage;
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;

@FacesConverter(forClass=Specialization.class)
public class PojoConverter implements Converter{
    public static List<Specialization> specilizationObject;

    static {
        specilizationObject = new ArrayList<Specialization>();
        specilizationObject.add(new Specialization("Vinayak", 10));
        specilizationObject.add(new Specialization("Pingale", 9));  
    }

    public Object getAsObject(FacesContext facesContext, UIComponent   
    component, String submittedValue) {
        if (submittedValue.trim().equals("")) {
            return null;
        } else {
            try {
                 for (Specialization p : specilizationObject) {
                    if (p.getName().equals(submittedValue)) {
                        return p;
                    }
                }

            } catch(NumberFormatException exception) {
                throw new ConverterException(new 
                FacesMessage(FacesMessage.SEVERITY_ERROR, "Conversion
                Error", "Not a valid Specialization"));
            }
        }

        return null;
    }

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

对您的托管Bean类进行了以下更改。克服NUll指针异常

package primefaces1;

import java.util.ArrayList;

import javax.annotation.PostConstruct;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

@ManagedBean(name = "appointentBean")
@SessionScoped
public class appointentBean {

private ArrayList<Specialization> specializationResult;
private Specialization selectedSpecialization  ;

@PostConstruct
public void init() {
    selectedSpecialization = new Specialization();
    selectedSpecialization.setName(new String());
    selectedSpecialization.setSpecialization_id(0);
}
    public appointentBean() {
        specializationResult= (ArrayList<Specialization>) 
                PojoConverter.specilizationObject;
    }
    public ArrayList<Specialization> getSpecializationResult() {
        // Here retrievie objects list from database 
                //and it works
        return specializationResult;
    }

    public void setSpecializationResult(ArrayList<Specialization> result) {
        this.specializationResult = result;
    }

    public Specialization getSelectedSpecialization() {
        if (this.selectedSpecialization != null)
              System.out.println("getSelectedSpecialization----"
                      + this.selectedSpecialization.getName());
        return this.selectedSpecialization;
    }

    public void setSelectedSpecialization(Specialization 
        selectedSpecialization) {       
        this.selectedSpecialization = selectedSpecialization;
    }

}

我对您的xhtml进行了一些微小的更改以显示值。

<h:body>

    <h:form id="me">
            <p:selectOneMenu value="#{appointentBean.selectedSpecialization}" >
                <f:selectItem itemLabel="Select One" itemValue=""></f:selectItem>
                <f:selectItems value="#{appointentBean.specializationResult}"
                    var="result" itemValue="#{result}" itemLabel="#{result.name}" />

            </p:selectOneMenu>

            <p:commandButton value="Szukaj" update="me:textid">
                </p:commandButton>
            <h:outputText value="NAME: "></h:outputText>
            <h:outputText  id="textid" value="#{appointentBean.selectedSpecialization.name}" rendered="#{not empty appointentBean.selectedSpecialization}"/>

    </h:form>

</h:body>

Answer 2

我发现自己处于与使用自定义转换器正确填充user2374573 Select2Menu相同的情况，但是所选项目为null。提出的解决方案是自定义转换器的一种变体，但它不能解决问题（至少对我而言）。值选择未按Primefaces文档中所述到达，这是因为SelectOneMenu使用String而不是Pojos进行操作。经过研究，最终我选择了一种中间解决方案。我没有使用pojo类型的变量来存储值，而是使用了一个String来存储元素的id，如下所示。此解决方案对于SelectOneMenu以及将Targer加载到Primefaces Picklist中使用的DualList中非常有用。这不是理想的解决方案，但是可以解决问题。

Java视图

public class PickListView  implements Serializable { 
    private static final long serialVersionUID = 1L;
    private List<CviConcesione> listaConcesion;
    private CviConcesione concesionSeleccionada;    
    private String concesionSeleccionadaS;  

    @Autowired
    private ConcesionesBO concesionesBO;    

    @PostConstruct
    public void init() {
    }
     
    public List<CviConcesione> getListaConcesion() {
        if (null != listaConcesion && !listaConcesion.isEmpty()) {
            return listaConcesion;  
        } else {
            listaConcesion = new ArrayList<CviConcesione>();            
            listaConcesion = concesionesBO.consultaTodasConcesiones();
            return listaConcesion;
        }
    }

    public void setListaConcesion(List<CviConcesione> listaConcesion) {
        this.listaConcesion = listaConcesion;
    }

    public ConcesionesBO getConcesionesBO() {
        return concesionesBO;
    }

    public void setConcesionesBO(ConcesionesBO concesionesBO) {
        this.concesionesBO = concesionesBO;
    }

    public CviConcesione getConcesionSeleccionada() {
        return concesionSeleccionada;
    }

    public void setConcesionSeleccionada(CviConcesione concesionSeleccionada) {
        this.concesionSeleccionada = concesionSeleccionada;
    }

    public String getConcesionSeleccionadaS() {
        return concesionSeleccionadaS;
    }

    public void setConcesionSeleccionadaS(String concesionSeleccionadaS) {
        this.concesionSeleccionadaS = concesionSeleccionadaS;
    }
}

用于选择一个菜单的HTML代码

<p:selectOneMenu 
            id="concesionR" 
            value="#{pickListView.concesionSeleccionadaS}" 
            style="width:125px" 
            dynamic="true"
            converter="#{concesionConverter}">
                <f:selectItem itemLabel="Seleccione" itemValue="" />
                <f:selectItems value="#{pickListView.listaConcesion}" 
                    var="concesion" 
                    itemLabel="#{concesion.conCodigo} - #{concesion.conDescripcion}" 
                    itemValue="#{concesion.conCodigo}"
                    ajax = "true"
                 />
                <p:ajax update="lineaR" process="@form" />                           
    </p:selectOneMenu>

a 类转换器

@FacesConverter("concesionConverter")
public class ConcesionesConverter implements Converter {

    public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
        if(value != null && value.trim().length() > 0) {
            try {
                PickListView service = (PickListView) fc.getExternalContext().getApplicationMap().get("pickListView");
                return service.getListaConcesion().get(Integer.parseInt(value));
            } catch(NumberFormatException e) {
                throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Conversion Error", "Not a valid theme."));
            }
        }
        else {
            return null;
        }
    }

    public String getAsString(FacesContext fc, UIComponent uic, Object object) {
        if(object != null) {
            return String.valueOf(((CviConcesione) object).getConId());
        }
        else {
            return null;
        }
    }   
}

此解决方案无法带来pojo，但会让您知道它已被选中，并显示pojo值。

Primefaces如何从selectOneMenu获取POJO

2 个答案:

编辑2