我是 JSF 的新手，遇到了一个问题。
我有一个用于显示国家列表的 selectOneMenu。当用户选择一个国家时，还有另一个 selectOneMenu 应该自动填充城市（在我的例子中为地区）。
我尝试了几次迭代来做同样的事情，但没有帮助。如果还需要任何其他帮助我，请告诉我。真的很感激。
更新：
添加监听器后的代码如下：
<p:outputLabel for="countryRegistration">#{msg['country']}:</p:outputLabel>
<p:selectOneMenu id="countryRegistration" value="#{mbcActor.geoData.country}" style="width:120px;" >
<f:attribute name="country" value="java.util.List" />
<f:converter converterId="ViewScopedObjectConverter"/>
<f:selectItem itemLabel="#{msg['selectCountry']}" itemValue=""/>
<f:selectItems value="#{geoLists.countryList}" var="country" itemLabel="#{country.name}"/>
<p:ajax listener="#{mbcActor.geoData.updateRegions}" render="cityRegistration"/>
</p:selectOneMenu>
<p:message for="countryRegistration"/>
<p:outputLabel for="cityRegistration">#{msg['city']}:</p:outputLabel>
<p:selectOneMenu id="cityRegistration" value="#{mbcActor.geoData.region}" style="width:120px;">
<f:attribute name="regions" value="java.util.List" />
<f:converter converterId="ViewScopedObjectConverter"/>
<f:selectItem itemLabel="#{msg['selectCity']}" itemValue=""/>
<!--<f:selectItems value="#{geoLists.regionForCountry}" var="region" itemLabel="#{region.name}"/>-->
<f:selectItems value="#{geoLists.getRegionForCountry(country)}" var="region" itemLabel="#{region.description}"/>
</p:selectOneMenu>
<p:message for="cityRegistration"/>
但它说：
Oct 05, 2013 2:04:53 AM com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: Target Unreachable, identifier 'mbcActor' resolved to null
javax.el.PropertyNotFoundException: Target Unreachable, identifier 'mbcActor' resolved to null
at org.apache.el.parser.AstValue.getTarget(AstValue.java:98)
at org.apache.el.parser.AstValue.invoke(AstValue.java:259)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:39)
at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl.processCustomListener(AjaxBehaviorListenerImpl.java:70)
at org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl.processArgListener(AjaxBehaviorListenerImpl.java:59)
at org.primefaces.component.behavior.ajax.AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxBehaviorListenerImpl.java:47)
豆子：
package xxx.core.entities;
// Generated Oct 20, 2009 11:07:18 AM by Hibernate Tools 3.2.2.GA
import javax.faces.event.ValueChangeEvent;
import javax.inject.Inject;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
import static javax.persistence.GenerationType.IDENTITY;
/**
* DataActorGeo
*/
@Entity
@Table(name = "dataActorGeo")
// @org.hibernate.annotations.Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
@Access(AccessType.PROPERTY)
public class DataActorGeo implements java.io.Serializable {
private Integer id;
private Country country;
private Region region;
private String city;
private String province;
private String address;
private String addressLine2;
private String postCode;
private String nationality;
private String phone1;
private String phone2;
private Double latitude;
private Double longitude;
private Actor actor;
private List<Region> regions;
@Inject
EntityManager entityManager;
public void updateRegions() {
//Country ctry = (Country) event.getNewValue();
try{
System.out.println("bbbbbbbbbbbbbbbbbbbbbbb" + country.toString());
// if (regions == null) {
this.regions = entityManager.createQuery("select r From Region r Where r.country.id = :countryId order by r.description ")
.setParameter("countryId", country.getId())
.getResultList();
//countryIdCache = country.getId();
// }
System.out.println("aaaaaaaaaaa" + regions.toString());
} catch(Exception e){System.out.println("cccccccccc"); }//return new ArrayList<Region>(); }
//return regions;
}
public DataActorGeo() {
}
public DataActorGeo(Country country, String city) {
this.country = country;
this.city = city;
}
public DataActorGeo(Country country, Region region, String city, String address, String postCode, String phone1, String phone2, Actor actor) {
this.country = country;
this.region = region;
this.city = city;
this.address = address;
this.postCode = postCode;
this.phone1 = phone1;
this.phone2 = phone2;
this.actor = actor;
}
@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "Country")
// @IndexedEmbedded(prefix = "country.")
public Country getCountry() {
return this.country;
}
public void setCountry(Country country) {
this.country = country;
}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "Region")
// @IndexedEmbedded(prefix = "region.")
public Region getRegion() {
return this.region;
}
public void setRegion(Region region) {
this.region = region;
}
public List<Region> getRegions()
{
return this.regions;
}
public void setRegions(List<Region> regions)
{
this.regions=regions;
}
@Column(name = "City")
// //@Field(index = Index.UN_TOKENIZED)
public String getCity() {
return this.city;
}
public void setCity(String city) {
this.city = city;
}
@Column(name = "province")
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
@Column(name = "address")
// //@Field(index = Index.TOKENIZED)
public String getAddress() {
return this.address;
}
public void setAddress(String address) {
this.address = address;
}
@Column(name = "addressLine2")
// //@Field(index = Index.TOKENIZED)
public String getAddressLine2() {
return addressLine2;
}
public void setAddressLine2(String addressLine2) {
this.addressLine2 = addressLine2;
}
@Column(name = "postCode")
// //@Field(index = Index.UN_TOKENIZED)
public String getPostCode() {
return this.postCode;
}
public void setPostCode(String postCode) {
this.postCode = postCode;
}
@Column(name = "nationality")
// //@Field(index = Index.UN_TOKENIZED)
public String getNationality() {
return nationality;
}
public void setNationality(String nationality) {
this.nationality = nationality;
}
@Column(name = "phone1")
// //@Field(index = Index.UN_TOKENIZED)
public String getPhone1() {
return phone1;
}
public void setPhone1(String phone1) {
this.phone1 = phone1;
}
@Column(name = "phone2")
// //@Field(index = Index.UN_TOKENIZED)
public String getPhone2() {
return phone2;
}
public void setPhone2(String phone2) {
this.phone2 = phone2;
}
@OneToOne(mappedBy = "geoData")
public Actor getActor() {
return actor;
}
public void setActor(Actor actor) {
this.actor = actor;
}
@Column(name = "latitude")
public Double getLatitude() {
return latitude;
}
@Column(name = "longitude")
public Double getLongitude() {
return longitude;
}
public void setLatitude(Double latitude) {
this.latitude = latitude;
}
public void setLongitude(Double longitude) {
this.longitude = longitude;
}
}
package xxx.lists;
import xxx.application.configuration.ISNetApp;
import xxx.core.entities.Country;
import xxx.core.entities.Region;
import javax.faces.bean.ViewScoped;
import javax.inject.Inject;
import javax.inject.Named;
import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
@Named
@ViewScoped
public class GeoLists implements Serializable {
@Inject
EntityManager entityManager;
@Inject
ISNetApp sNetApp;
private List<Country> countryList;
public List<Country> getCountryList() {
if (countryList == null) {
String query = "select c from Country c order by c.ordering, c.name";
countryList = (List<Country>) entityManager.createQuery(query).getResultList();
}
return countryList;
}
public void setCountryList(List<Country> countryList) {
this.countryList = countryList;
}
private List<Country> deliveryCountryList;
public List<Country> getDeliveryCountryList() {
if (deliveryCountryList == null) {
String query = "select c from Country c where c.groups LIKE '%D,%' order by c.ordering, c.name";
deliveryCountryList = (List<Country>) entityManager.createQuery(query).getResultList();
}
return deliveryCountryList;
}
public void setDeliveryCountryList(List<Country> deliveryCountryList) {
this.deliveryCountryList = deliveryCountryList;
}
public Country getCountryByIsoCode2(String isoCode2) {
String query = "select c from Country c where c.isoCode2=:ic";
try {
return (Country) entityManager.createQuery(query).setParameter("ic", isoCode2).getSingleResult();
} catch (NoResultException e) {
return null;
}
}
private List<Region> regionForCountry;
private int countryIdCache;
private List<Region> regions;
public List<Region> getRegions(){
return this.regions;
}
public void setRegions(List<Region> regions){
this.regions = regions;
}
public List<Region> getRegionForCountryById(Long countryId) {
Country country = entityManager.find(Country.class, countryId.intValue());
return getRegionForCountry(country);
}
public List<Region> getRegionForCountry(Country country) {
try{
System.out.println("bbbbbbbbbbbbbbbbbbbbbbb" + country.toString());
//if (regionForCountry == null || countryIdCache != country.getId()) {
regionForCountry = entityManager.createQuery("select r From Region r Where r.country.id = :countryId order by r.description ")
.setParameter("countryId", 1)//country.getId())
.getResultList();
// countryIdCache = country.getId();
//}
// System.out.println("aaaaaaaaaaa" + regionForCountry.toString());
} catch(Exception e){System.out.println("cccccccccc"); return new ArrayList<Region>(); }
return regionForCountry;
}
public void setRegionForCountry(List<Region> regionForCountry) {
this.regionForCountry = regionForCountry;
}
private Country mainCountry;
private Country country;
public void setCountry(Country country) {
this.country=country;
}
public Country getCountry(){
return this.country;
}
public Country getMainCountry() {
if (mainCountry == null) {
mainCountry = entityManager.find(Country.class, sNetApp.getMainCountryId());
}
return mainCountry;
}
public void setMainCountry(Country mainCountry) {
this.mainCountry = mainCountry;
}
private List<Country> specificGroupCountryList;
private String groupCache;
public List<Country> getSpecificGroupCountryList(String group) {
if (specificGroupCountryList == null || groupCache == null || groupCache.compareTo(group) != 0) {
String query = "from Country where groups LIKE '%" + group + ",%' order by ordering, name";
specificGroupCountryList = (List<Country>) entityManager.createQuery(query).getResultList();
}
return specificGroupCountryList;
}
public void setSpecificGroupCountryList(List<Country> specificGroupCountryList) {
this.specificGroupCountryList = specificGroupCountryList;
}
}
mbcActor 是一个参数，定义为：
<ui:param name="mbcActor" value="#{registrationHelper.newActor}"/>
摘要演员：
@MappedSuperclass
public class AbstractActor extends AbstractGenericElement implements java.io.Serializable, IGenericElement, EmailContact {
private static Logger log = LoggerFactory.getLogger(AbstractActor.class);
public static enum Gender {
Male,
Female
}
/**
* Transient
*/
private boolean selected;
private Integer id;
private Long version;
private byte type;
private String language;
private byte status;
private byte publicStatus;
private String permalink;
private Boolean customPermalink;
private String displayName;
private String forename;
private String surname;
private Gender gender;
private Date birthday;
private String mobile;
private Byte subType;
private String stringValue1;
private String stringValue2;
private String stringValue3;
@Transient
@XmlTransient
private Integer age;
private String profileMessage;
private String statusMessage;
private String email;
private String username;
private String passwordHash;
private int passwordHashIterations;
private String salt;
private String timezone;
private String activationCode;
private Boolean activationEmailSent;
private Integer completitionPercentage;
private Integer ordering;
// Stats
private ActorStats stats;
// Extensions
private DataActorGeo geoData;
private DataActorExtended dataActorExtended;
private Boolean acceptNewsletter;
private Boolean emailAlertsEnabled;
private Set<ActorTag> actorTags = new HashSet<ActorTag>(0);
private List<Role> roles = new ArrayList<Role>(0);
private Actor newDataToBeModerated;
private Date expireDate;
private Integer points;
private BigDecimal wallet;
private Byte emailAlertsType;
private Byte emailOffersType;
private String emailHash;
// Data blob
private byte[] data;
private Set<ActorInCategory> actorInCategories = new HashSet<ActorInCategory>(
0);
private List<ActorAttribute> actorAttributes = new ArrayList<ActorAttribute>(0);
public AbstractActor() {
this.version = 1l;
this.activationEmailSent = false;
this.acceptNewsletter = true;
this.emailAlertsEnabled = true;
this.completitionPercentage = 0;
this.customPermalink = false;
this.wallet = new BigDecimal(0);
this.points = 0;
this.emailAlertsType = ActorConstants.RECURRING_EMAIL_TYPE_NONE;
this.emailOffersType = ActorConstants.RECURRING_EMAIL_TYPE_NONE;
}
public AbstractActor(byte type, byte status) {
this.version = 1l;
this.type = type;
this.status = status;
this.publicStatus = ActorConstants.PUBLIC_STATUS_OFFLINE;
this.activationEmailSent = false;
this.acceptNewsletter = true;
this.emailAlertsEnabled = true;
this.completitionPercentage = 0;
this.customPermalink = false;
this.wallet = new BigDecimal(0);
this.points = 0;
this.emailAlertsType = ActorConstants.RECURRING_EMAIL_TYPE_NONE;
this.emailOffersType = ActorConstants.RECURRING_EMAIL_TYPE_NONE;
}
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JoinColumn(name = "geoData", nullable = true)
@org.hibernate.annotations.Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public DataActorGeo getGeoData() {
return this.geoData;
}
public void setGeoData(DataActorGeo geoData) {
this.geoData = geoData;
}
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "actor")
public Set<ActorInCategory> getActorInCategories() {
return this.actorInCategories;
}
public void setActorInCategories(Set<ActorInCategory> actorInCategories) {
this.actorInCategories = actorInCategories;
}
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "actor")
public List<ActorAttribute> getActorAttributes() {
return this.actorAttributes;
}
public void setActorAttributes(List<ActorAttribute> actorAttributes) {
this.actorAttributes = actorAttributes;
}
}