在“创建新用户”jsf 页面中,我有一个带有自定义转换器的 SelectOneMenu 和一个 noSelectionOption selectItem,如下所示:(省略了不相关的代码)
新用户.xhtml
<h:form>
<h:selectOneMenu value="#{newUserController.user.department}"
required="true" converter="departmentConverter">
<f:selectItem itemLabel="Select a department" noSelectionOption="true"/>
<f:selectItems value="#{newUserController.departments}"
var="dep" itemLabel="#{dep.name}" itemValue="#{dep}"/>
</h:selectOneMenu>
<p:commandButton action="#{newUserController.saveUser}"
value="#{bundle.Save}"
ajax="false"/>
</h:form>
新用户控制器.java
@ManagedBean
@ViewScoped
public class NewUserController implements Serializable {
private static final long serialVersionUID = 10L;
@EJB private UserBean userBean;
private List<Department> departments;
private User user;
public NewUserController () {
}
@PostConstruct
public void init(){
user = new User();
departments = userBean.findAllDepartments();
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public List<Department> getDepartments(){
return departments;
}
public String saveUser() {
// Business logic
}
}
部门转换器.java
@FacesConverter(value="departmentConverter")
public class DepartmentConverter extends EntityConverter {
public DepartmentConverter(){
super(Department.class);
}
}
所有实体的超级转换器
public class EntityConverter<E> implements Converter{
protected Class<E> entityClass;
public EntityConverter(Class<E> type) {
entityClass = type;
}
@Override
public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
if (value == null || value.length() == 0) {
return null;
}
try {
InitialContext ic = new InitialContext();
UserBean ub = (UserBean)ic.lookup("java:global/CompetenceRegister/UserBean");
return ub.find(entityClass, getKey(value));
} catch (NamingException e) {
return null;
}
}
Long getKey(String value) {
Long key;
key = Long.valueOf(value);
return key;
}
String getStringKey(Long value) {
StringBuilder sb = new StringBuilder();
sb.append(value);
return sb.toString();
}
@Override
public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
if (object == null) {
return null;
}
if (object instanceof AbstractEntity) {
AbstractEntity e = (AbstractEntity) object;
return getStringKey(e.getId());
}
else
throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + entityClass.getName());
}
}
但是,当我发布带有“选择部门”选项的表单时,它会将标签发送到转换器中的 getAsObject 而不是 null,从而导致转换器在 getKey 中引发异常(尝试将包含 id 的字符串转换为沿着)。将 selectItem 的 itemValue 属性设置为 null 无效。该系列中的物品可以与转换器完美配合。有谁知道是什么原因造成的?
更新一个我忘了提的有趣的事情;如果我从 SelectOneMenu 中删除转换器属性,则 noSelectionAttribute 可以正常工作,但是由于默认转换器不知道如何转换我的对象,因此帖子无法选择真正的部门。这是否意味着 noSelectionOption=true应该发送它的标签,而转换器应该以某种方式处理它?