我想在我的 JSF 应用程序中创建一个选择一个菜单对象。每当我尝试填写列表时，我都会得到“无法实例化类”异常。这是我的豆：
@ManagedBean(name = "districtController")
@SessionScoped
public class DistrictController implements Serializable {
private District current;
private DataModel items = null;
@EJB
private TestoBeans.DistrictFacade ejbFacade;
private PaginationHelper pagination;
private int selectedItemIndex;
public DistrictController() {
Query q = em.createQuery("select d.dName from District d",District.class);
List<String> values = q.getResultList();
for(String d:values){
System.out.println(d);
}
}
@PersistenceContext(unitName = "TestoIBBPU")
private EntityManager em;
@Resource
private javax.transaction.UserTransaction utx;
public District getSelected() {
if (current == null) {
current = new District();
selectedItemIndex = -1;
}
return current;
}
private DistrictFacade 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 = (District) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "View";
}
public String prepareCreate() {
current = new District();
selectedItemIndex = -1;
return "Create";
}
public String create() {
try {
getFacade().create(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("DistrictCreated"));
return prepareCreate();
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String prepareEdit() {
current = (District) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "Edit";
}
public String update() {
try {
getFacade().edit(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("DistrictUpdated"));
return "View";
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String destroy() {
current = (District) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
performDestroy();
recreatePagination();
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("DistrictDeleted"));
} 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;
}
private void recreatePagination() {
pagination = 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 = District.class)
public static class DistrictControllerConverter implements Converter {
public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
if (value == null || value.length() == 0) {
return null;
}
DistrictController controller = (DistrictController) facesContext.getApplication().getELResolver().
getValue(facesContext.getELContext(), null, "districtController");
return controller.ejbFacade.find(getKey(value));
}
java.lang.Integer getKey(String value) {
java.lang.Integer key;
key = Integer.valueOf(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 District) {
District o = (District) object;
return getStringKey(o.getId());
} else {
throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + District.class.getName());
}
}
}
private Map<String,String> district = new HashMap<String,String>();
public Map<String, String> getDistrict() {
return district;
}
public void setDistrict(Map<String, String> district) {
this.district = district;
}
public void persist(Object object) {
try {
utx.begin();
em.persist(object);
utx.commit();
} catch (Exception e) {
Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
throw new RuntimeException(e);
}
}
}
我怎样才能做到这一点？感谢您的任何想法。