JSF 1.2：第一次設置下拉列表的選項沒有更新

Question

我已經使用jsf 1.2編寫了一個程序。在這個程序中，用戶需要選擇他的國家，州和城市。當他選擇國家/地區時，他必須在下拉菜單&中看到狀態列表，當他選擇某個州時，他必須在下拉列表中查看其中的城市。

爲此，我創建了2個類，1個內部類和一個jsf頁面。

當我選擇一個國家時，我可以看到立即顯示狀態下拉菜單。

問題是當一個狀態改變時，城市的下拉不能馬上看到。只有在第二次改變後才能看到城市的下降。

（注：我不能去除方法cityChangeListener()在此代碼，因爲我需要使用國家代碼，國家代碼，城市代碼，和隨機數生成ID。）

任何幫助受到高度讚賞。

這裏是我的代碼（4檔）：

文件：faces-config.xml中

<?xml version='1.0' encoding='UTF-8'?> 
<faces-config version="1.2" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_1_2.xsd"> 
    <managed-bean> 
     <managed-bean-name>formBackingBean</managed-bean-name> 
     <managed-bean-class>FormBackingBean</managed-bean-class> 
     <managed-bean-scope>session</managed-bean-scope></managed-bean> 
</faces-config> 

文件：newjsf.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%> 
<%@taglib prefix="f" uri="http://java.sun.com/jsf/core"%> 
<%@taglib prefix="h" uri="http://java.sun.com/jsf/html"%> 
<f:view> 
    <h:form> 
     <h:inputText 
      id="input" 
      value="#{formBackingBean.input}" 
      immediate="true" 
      disabled="true" 
      /> 
     <br/> 
     <h:selectOneMenu 
      id="country" 
      value="#{formBackingBean.country}" 
      valueChangeListener="#{formBackingBean.countryChangeListener}" 
      immediate="true" 
      onchange="submit();" 
      > 
      <f:selectItems 
       id="countries" 
       value="#{formBackingBean.countries}" 
       /> 
     </h:selectOneMenu> 
     <br/> 
     <h:selectOneMenu 
      id="state" 
      value="#{formBackingBean.state}" 
      valueChangeListener="#{formBackingBean.stateChangeListener}" 
      immediate="true" 
      onchange="submit();" 
      rendered="#{formBackingBean.states!=null}" 
      > 
      <f:selectItems 
       id="states" 
       value="#{formBackingBean.states}" 
       /> 
     </h:selectOneMenu> 
     <br/> 
     <h:selectOneMenu 
      id="city" 
      value="#{formBackingBean.city}" 
      immediate="true" 
      onchange="submit();" 
      rendered="#{formBackingBean.cities!=null}" 
      valueChangeListener="#{formBackingBean.cityChangeListener}" 
      > 
      <f:selectItems 
       id="cities" 
       value="#{formBackingBean.cities}" 
       /> 
     </h:selectOneMenu> 
    </h:form> 
</f:view> 

文件：FormBackingBean.java

import java.util.List; 
import javax.faces.context.FacesContext; 
import javax.faces.event.ValueChangeEvent; 
import javax.faces.model.SelectItem; 

public class FormBackingBean { 

    private String input; 
    private String country; 
    private String state; 
    private String city; 
    private List<SelectItem>countries=GeoMapLister.WORLD.getNamesOfPlacesWithin();//MapLister.countryList; 
    private List<SelectItem>states=null; 
    private List<SelectItem>cities=null; 
    public FormBackingBean() { 
    } 

    public String getCity() { 
     return city; 
    } 

    public String getCountry() { 
     return country; 
    } 

    public String getState() { 
     return state; 
    } 

    public void setCity(String city) { 
     this.city = city; 
     FacesContext.getCurrentInstance().renderResponse(); 
    } 

    public void setCountry(String country) { 
     this.country = country; 
     FacesContext.getCurrentInstance().renderResponse(); 
    } 

    public void setState(String state) { 
     this.state = state; 
    } 

    public List<SelectItem> getCities() { 
     return cities; 
    } 

    public List<SelectItem> getCountries() { 
     return countries; 
    } 

    public List<SelectItem> getStates() { 
     return states; 
    } 

    public void setCities(List<SelectItem> cities) { 
     this.cities = cities; 
    } 

    public void setCountries(List<SelectItem> countries) { 
     this.countries = countries; 
    } 

    public void setStates(List<SelectItem> states) { 
     this.states = states; 
    } 

    public String getInput() { 
     return input; 
    } 

    public void setInput(String input) { 
     this.input = input; 
    } 

    public void countryChangeListener(final ValueChangeEvent valueChangeEvent){ 
     input=valueChangeEvent.getNewValue().toString(); 
     states=GeoMapLister.WORLD.getPlacesWithin().get(input).getNamesOfPlacesWithin(); 
     state=null; 
     cities=null; 
     city=null; 
     FacesContext.getCurrentInstance().renderResponse(); 
    } 
    public void stateChangeListener(final ValueChangeEvent valueChangeEvent){ 
     input=valueChangeEvent.getNewValue().toString(); 
     cities=GeoMapLister.WORLD.getPlacesWithin() 
       .get(country).getPlacesWithin().get(input) 
       .getNamesOfPlacesWithin(); 
     city=null; 
     FacesContext.getCurrentInstance().renderResponse(); 
    } 
    public void cityChangeListener(final ValueChangeEvent valueChangeEvent){ 
     input=valueChangeEvent.getNewValue().toString(); 
     FacesContext.getCurrentInstance().renderResponse(); 
    } 
} 

file：GeoMapLister .java

import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
import javax.faces.model.SelectItem; 

public class GeoMapLister { 
    public static class GeographicalLocation{ 
     private final GeographicalLocation parent; 
     private final String code; 
     private final String name; 
     private final List<SelectItem>namesOfPlacesWithin; 
     private final HashMap<String,GeographicalLocation>placesWithin; 

     public GeographicalLocation(GeographicalLocation parent,String code, String name,boolean leaf) { 
      this.parent = parent; 
      this.name = name; 
      this.code= code; 
      ArrayList<SelectItem> namesofplaceswithin = null; 
      HashMap<String,GeographicalLocation> placeswithin = null; 
      if(!leaf){ 
       namesofplaceswithin = new ArrayList<SelectItem>(); 
       namesofplaceswithin.add(new SelectItem(null, "- select -")); 
       placeswithin = new HashMap<String,GeographicalLocation>(); 
       placeswithin.put(null, null); 
      } 
      this.namesOfPlacesWithin = namesofplaceswithin; 
      this.placesWithin = placeswithin; 
     } 

     public String getName() { 
      return name; 
     } 

     public GeographicalLocation getParent() { 
      return parent; 
     } 

     public List<SelectItem> getNamesOfPlacesWithin() { 
      return namesOfPlacesWithin; 
     } 

     public String getCode() { 
      return code; 
     } 

     public GeographicalLocation addPlaceWithin(String code,String name,boolean leaf){ 
      GeographicalLocation newGeographicalLocation = new GeographicalLocation(this, code,name,leaf); 
      placesWithin.put(code,newGeographicalLocation); 
      namesOfPlacesWithin.add(new SelectItem(code, name)); 
      return newGeographicalLocation; 
     } 

     public HashMap<String, GeographicalLocation> getPlacesWithin() { 
      return placesWithin; 
     } 

     List<SelectItem> getPlacesWithin(String input) { 
      return placesWithin.get(input).namesOfPlacesWithin; 
     } 

    } 

    public static final GeographicalLocation WORLD=new GeographicalLocation(null, "WORLD","WORLD",false); 

    static 
    { 
     GeographicalLocation IN = WORLD.addPlaceWithin("IN", "India", false); 
     GeographicalLocation MH = IN.addPlaceWithin("MH", "Maharashtra", false); 
     MH.addPlaceWithin("MU", "Mumbai", true); 
     MH.addPlaceWithin("PU", "Pune", true); 
     MH.addPlaceWithin("NA", "Nashik", true); 
     GeographicalLocation KA = IN.addPlaceWithin("KA", "Karnataka", false); 
     KA.addPlaceWithin("BA", "Bangalore", true); 
     KA.addPlaceWithin("MA", "Mangalore", true); 
     GeographicalLocation BE = IN.addPlaceWithin("BE", "West Bengal", false); 
     BE.addPlaceWithin("KO", "Kolkata", true); 
     BE.addPlaceWithin("KH", "Kharagpur", true); 

     //-------------- 
     GeographicalLocation UK = WORLD.addPlaceWithin("UK", "U.K.", false); 
     GeographicalLocation YO = UK.addPlaceWithin("YO", "York", false); 
     YO.addPlaceWithin("SS", "Sussex", true); 
     YO.addPlaceWithin("MS", "Middlesex", true); 

     //-------------- 
     GeographicalLocation US = WORLD.addPlaceWithin("US", "U.S.A.", false); 
     GeographicalLocation NY = US.addPlaceWithin("NY", "New York", false); 
     NY.addPlaceWithin("NC", "New York city", true); 
     NY.addPlaceWithin("NU", "New York urban", true); 
     GeographicalLocation CA = US.addPlaceWithin("CA", "California", false); 
     CA.addPlaceWithin("WA", "Washington, district of California", true); 
     CA.addPlaceWithin("SI", "Silicon Valley", true); 
     CA.addPlaceWithin("VS", "Very-Silly-Con Valley", true); 

    } 
} 

Answer 1

您是否試過閱讀here？有一個例子適用於子菜單。