我在实现两个SelectOneMenu控件时遇到了麻烦，第二个控件中的数据取决于第一个控件的选择。这个例子在primeFaces展示页面上几乎与我要实现的相同：http://www.primefaces.org/showcase-labs/ui/pprSelect.jsf，除了我必须从数据库中获取数据。上面的示例在同一项目中工作正常。我使用的是NetBeans 7.0和GlassFish 3.1以及PrimeFaces 3.0.M2（最新版本为2011年6月20日）。JSF页面和托管bean的源代码已附上。
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:p="http://primefaces.prime.com.tr/ui"
xmlns:f="http://java.sun.com/jsf/core">
<h:head><title>Facelet Title</title></h:head>
<h:body>
<p:log />
<center>
<h:form>
<h:outputText value="State: "/>
<p:selectOneMenu id="selectState" value="#{stateCityBean.selectedStateArray}">
<f:selectItem itemLabel="Select Any" itemValue="Empty String"/>
<p:ajax update="selectCity" listener="#{stateCityBean.updateCityMap}"/>
<f:selectItems value="#{stateCityBean.stateMap}" />
</p:selectOneMenu>
<p></p>
<h:outputText value="City: "/>
<p:selectOneMenu id="selectCity" value="#{stateCityBean.selectedCityArray}">
<f:selectItem itemLabel="Select Any" itemValue="Empty String"/>
<f:selectItems value="#{stateCityBean.cityMap}"/>
</p:selectOneMenu>
</h:form>
</center>
</h:body>
StateCityBean.java
package com.xyz.mbeans;
import com.iwizability.priceinfo.dao.*;
import com.iwizability.priceinfo.pojo.*;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.context.FacesContext;
import javax.faces.context.Flash;
import javax.faces.event.ValueChangeEvent;
@ManagedBean
@SessionScoped
public class StateCityBean {
private String selectedStateArray;
private Map<String, State> StateMap;
private Map<String, City> CityMap;
private String selectedCityArray;
public StateCityBean() {
System.out.println("Inside.............. ");
StateMap = new LinkedHashMap<String, State>();
CityMap = new LinkedHashMap<String, City>();
}
public String getSelectedStateArray() {return selectedStateArray;}
public void setSelectedStateArray(String selectedStateArray) {this.selectedStateArray = selectedStateArray;}
public Map<String, State> getStateMap() {
StateDaoImpl stateObj = new StateDaoImpl();
StateMap = stateObj.getState();
return StateMap;
}
public void setStateMap(Map<String, State> stateArray) {this.StateMap = stateArray;}
public String getSelectedCityArray() {return selectedCityArray;}
public void setSelectedCityArray(String selectedCityArray) {this.selectedCityArray = selectedCityArray;}
public Map<String, City> getCityMap() {
CityDaoImpl cityObj = new CityDaoImpl();
int stateId = 0;
if (selectedStateArray != null && !selectedStateArray.equals("")) {
stateId = StateMap.get(selectedStateArray).getId();
}
CityMap = cityObj.getCity(stateId);
return CityMap;
}
public void setCityMap(Map<String, City> CityArray) {
this.CityMap = CityArray;
}
public void updateCityMap() {
CityDaoImpl cityObj = new CityDaoImpl();
int stateId = 0;
if (selectedStateArray != null && !selectedStateArray.equals("")) {
stateId = StateMap.get(selectedStateArray).getId();
this.CityMap = cityObj.getCity(stateId);
}
}
在调试时，我可以看到updateCityMap方法被调用，但SelectedStateArray变量为null。即使强制更改绑定的CityMap变量的值，也不会更新selectCity下拉列表。
正如你所猜测的那样，我对JSF还很陌生，但问题的复杂性还增加了一个事实，那就是我正在使用仍处于开发中版本的标签库...