转换器类抛出异常java.lang.IllegalArgumentException

Question

我在我的JSF页面中有p：selectOneMenu，当我运行我的JSF页面时，我从Converter类中得到以下异常。

java.lang.IllegalArgumentException: object 5634 is of type java.lang.String; 
expected type: test.entity.Employee 

如何解决此问题？

，我有以下的实体类

@Entity 
public class Employee implements Serializable { 

private String employeeNumber; 
private String employeeName; 

/* getters and setters */ 

EmployeeConverter类

@Component("employeeConverter") 
@FacesConverter(forClass = Employee.class) 

@Inject 
EmployeeService employeeService; 

@Override 
public Object getAsObject(FacesContext facesContext, UIComponent component, String value) { 

    if (value == null || value.length() == 0) { 
     return null; 
    } 
    EmployeeService employeeService= (EmployeeService) facesContext.getApplication().getELResolver(). 
      getValue(facesContext.getELContext(), null, "employeeService"); 
    return employeeService.getEmployees(); 
} 

@Override 
public String getAsString(FacesContext facesContext, UIComponent component, Object object) { 

      if (object == null) { 
       return null; 
      } 
      if (object instanceof Employee) { 
       Employee emp = (Employee) object; 
       String val = emp.getEmployeeNumber(); 
       return val; 
      } else { 
throw new IllegalArgumentException("object " + 
object + " is of type " + object.getClass().getName() + "; expected type: " + 
Employee.class.getName()); 
      } 
} 

和JSF页面

<p:selectOneMenu value="#{mb.employee}" converter="#{employeeConverter}"> 
<f:selectItems value="#{cmb.employeeList}" var="emp" 
itemLabel="#{emp.employeeName}" itemValue="#{emp.employeeNumber}"/> 
<p:ajax listener="#{mb.handleChange}" process="@this"/> 
</p:selectOneMenu> 

更新1

改进的转换方法getAsObject

private List<Employee> employee; 

@Override 
    public Object getAsObject(FacesContext facesContext, UIComponent component, 
      String value) { 
     System.out.println("reached in converter"); 
     try { 
      if (value == null || value.length() == 0) { 
       return null; 
      } else { 
       employee = getEmployeeService().getEmployees(); 
       for (Employee emp : employee) { 
        if (emp.getEmployeeNUmber() == value) { 
         return emp; 
        } 
       } 
      } 

     } catch (Exception e) { 
      System.out.println("exception from getAsObject " + e.getMessage());    
     } 
     return null; 
    } 

更新2

ManagedBean 

@PostConstruct 
    public void loadEmployees(){ 

     try {   
      List<Employee> emp = getEmployeeService().getEmployees();   
      employeeList = emp; 

     } 
     catch(Exception e){ 
      e.printStackTrace(); 
      System.out.println("exception from loadEmployees "+e.getMessage()); 
     } 

    } 

Answer 1

在您的getAsObject方法中，您对达到的价值无所作为。在这里，你将收到你的#{emp.employeeNumber}，所以你必须将它转换为Employee（可能你必须实现一个方法，它使用服务定位器通过id加载Employee）并返回对象本身。

您也正在使用EL（#{employeeConverter}）引用转换器，您必须以直接方式执行此操作。最后，元素列表必须由SelectItem组成，以使f:selectItems标签正常工作。

Answer 2

不要指定字符串的项值，你需要指定转换后的对象（雇员）本身。

变化itemValue="#{emp}"

见BalusC回答这个question。