JSF 错误目标无法到达，“null”返回 null [重复]

Question

大家好，现在我正在使用 JSF 2.0 和 EJB3，我使用 Primefaces 来显示错误消息或成功消息，我有两个问题是 一个当我把按钮 sumit（JSF 命令按钮）下一页错误显示

/register.xhtml @26,172 value="#{userController.user.username}": 目标不可达，'null' 返回 null

我的代码是

用户实体

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.demoejb.entity;

import java.io.Serializable;
import java.util.Date;
import java.util.List;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

/**
 *
 * @author KencyWindy
 */
@Entity
@Table(name = "iuser")
@NamedQueries({
    @NamedQuery(name = "Iuser.findAll", query = "SELECT i FROM Iuser i"),
    @NamedQuery(name = "Iuser.findByUid", query = "SELECT i FROM Iuser i WHERE i.uid = :uid"),
    @NamedQuery(name = "Iuser.findByUsername", query = "SELECT i FROM Iuser i WHERE i.username = :username"),
    @NamedQuery(name = "Iuser.findByPassword", query = "SELECT i FROM Iuser i WHERE i.password = :password"),
    @NamedQuery(name = "Iuser.findByPnum", query = "SELECT i FROM Iuser i WHERE i.pnum = :pnum"),
    @NamedQuery(name = "Iuser.findByZipcode", query = "SELECT i FROM Iuser i WHERE i.zipcode = :zipcode"),
    @NamedQuery(name = "Iuser.findByState", query = "SELECT i FROM Iuser i WHERE i.state = :state"),
    @NamedQuery(name = "Iuser.findByDob", query = "SELECT i FROM Iuser i WHERE i.dob = :dob"),
    @NamedQuery(name = "Iuser.findByEmail", query = "SELECT i FROM Iuser i WHERE i.email = :email"),
    @NamedQuery(name = "Iuser.findByLastlogin", query = "SELECT i FROM Iuser i WHERE i.lastlogin = :lastlogin"),
    @NamedQuery(name = "Iuser.findByRegdate", query = "SELECT i FROM Iuser i WHERE i.regdate = :regdate"),
    @NamedQuery(name = "Iuser.findByAddress", query = "SELECT i FROM Iuser i WHERE i.address = :address"),
    @NamedQuery(name = "Iuser.findByCity", query = "SELECT i FROM Iuser i WHERE i.city = :city")})
public class Iuser implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "uid")
    private Integer uid;
    @Basic(optional = false)
    @Column(name = "username")
    private String username;
    @Basic(optional = false)
    @Column(name = "password")
    private String password;
    @Basic(optional = false)
    @Column(name = "pnum")
    private int pnum;
    @Basic(optional = false)
    @Column(name = "zipcode")
    private int zipcode;
    @Basic(optional = false)
    @Column(name = "state")
    private String state;
    @Basic(optional = false)
    @Column(name = "dob")
    @Temporal(TemporalType.TIMESTAMP)
    private Date dob;
    @Basic(optional = false)
    @Column(name = "email")
    private String email;
    @Column(name = "lastlogin")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastlogin;
    @Column(name = "regdate")
    @Temporal(TemporalType.TIMESTAMP)
    private Date regdate;
    @Basic(optional = false)
    @Column(name = "address")
    private String address;
    @Basic(optional = false)
    @Column(name = "city")
    private String city;
    @JoinColumn(name = "group", referencedColumnName = "g_id")
    @ManyToOne(optional = false)
    private Igroup igroup;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "iuser")
    private List<Irent> irentList;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "iuser")
    private List<Ipayment> ipaymentList;

    public Iuser() {
    }

    public Iuser(Integer uid) {
        this.uid = uid;
    }

    public Iuser(Integer uid, String username, String password, int pnum, int zipcode, String state, Date dob, String email, String address, String city) {
        this.uid = uid;
        this.username = username;
        this.password = password;
        this.pnum = pnum;
        this.zipcode = zipcode;
        this.state = state;
        this.dob = dob;
        this.email = email;
        this.address = address;
        this.city = city;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public int getPnum() {
        return pnum;
    }

    public void setPnum(int pnum) {
        this.pnum = pnum;
    }

    public int getZipcode() {
        return zipcode;
    }

    public void setZipcode(int zipcode) {
        this.zipcode = zipcode;
    }

    public String getState() {
        return state;
    }

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

    public Date getDob() {
        return dob;
    }

    public void setDob(Date dob) {
        this.dob = dob;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getLastlogin() {
        return lastlogin;
    }

    public void setLastlogin(Date lastlogin) {
        this.lastlogin = lastlogin;
    }

    public Date getRegdate() {
        return regdate;
    }

    public void setRegdate(Date regdate) {
        this.regdate = regdate;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getCity() {
        return city;
    }

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

    public Igroup getIgroup() {
        return igroup;
    }

    public void setIgroup(Igroup igroup) {
        this.igroup = igroup;
    }

    public List<Irent> getIrentList() {
        return irentList;
    }

    public void setIrentList(List<Irent> irentList) {
        this.irentList = irentList;
    }

    public List<Ipayment> getIpaymentList() {
        return ipaymentList;
    }

    public void setIpaymentList(List<Ipayment> ipaymentList) {
        this.ipaymentList = ipaymentList;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (uid != null ? uid.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Iuser)) {
            return false;
        }
        Iuser other = (Iuser) object;
        if ((this.uid == null && other.uid != null) || (this.uid != null && !this.uid.equals(other.uid))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.demoejb.entity.Iuser[uid=" + uid + "]";
    }

}

会话 Bean 类

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.demoejb.DAO;

import com.demoejb.entity.Igroup;
import com.demoejb.entity.Iuser;
import java.util.List;
import javax.ejb.Stateless;
import javax.ejb.LocalBean;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

/**
 *
 * @author KencyWindy
 */
@Stateless
@LocalBean
public class UserSessionBean {
    @PersistenceContext(unitName = "DemoEJB3-ejbPU")
    private EntityManager em;

    // Add business logic below. (Right-click in editor and choose
    // "Insert Code > Add Business Method")



    public void persist(Object object) {
        em.persist(object);
    }

   public Object persistEntity(Object entity) {
         em.persist(entity);
         return entity;
    }

   public Object updateEntity(Object entity){
    return em.merge(entity);
   }

   public void removeUser(Iuser user){
    user = em.find(Iuser.class, user.getUid());
   }

   public List<Iuser> getAllUser(){
    return em.createNamedQuery("Iuser.findAll").getResultList();
   }

   /*Check username and email if new user enter into form
    * if exist throw exception, this feature will be used in controller
    */
   public Iuser checkExistUser(String email,String username){
        Iuser entity = null;
       try {
            javax.persistence.Query query = em.createQuery("select u from iuser u where iuser.email = : email or iuser.username = :username");
            query.setParameter("email", email);
            query.setParameter("username", username);
            entity = (Iuser) query.getResultList();
       } catch (Exception e) {
       }
        return entity;
   }

   public Iuser addUser(Iuser user){

        persist(user);
       return  user;
   }

    public void persist1(Object object) {
        em.persist(object);
    }
    /*
     * Get all group in database
     */
    public List<Igroup> getGroup() {

        return em.createNamedQuery("Igroup.findAll").getResultList();
    }


}

JSF 托管 Bean 类

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package com.demo.controller;

import com.demoejb.DAO.UserSessionBean;
import com.demoejb.entity.Igroup;
import com.demoejb.entity.Iuser;
import java.util.Date;
import java.util.List;
import javax.ejb.EJB;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.model.SelectItem;


/**
 *
 * @author KencyWindy
 */
public class UserController {
    @EJB
    private UserSessionBean userSessionBean;
    private Iuser user;






    /** Creates a new instance of UserController */
    public UserController() {
    }

    public Iuser getUser() {
        return user;
    }

    public void setUser(Iuser user) {
        this.user = user;
    }

     public String addUser(){
        String toReturn =  "false";
        String email = user.getEmail();
        String username = user.getUsername();
        try {
                if(userSessionBean.checkExistUser(email, username) != null){
                    FacesContext context = FacesContext.getCurrentInstance();
                     context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_INFO,
                    "Error", "username or email id has been exist!"));
                    toReturn = "False";
                }
                 else   {
                 Igroup g = new Igroup();
                 Date date = new Date();
                 java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                 String getDate = sdf.format(date);
                 Date regDate = sdf.parse(getDate);
                 user.setRegdate(regDate);
                 user.setLastlogin(regDate);
                 g.setGId(1);
                 user.setIgroup(g);
                 user = userSessionBean.addUser(user);
                 FacesContext context = FacesContext.getCurrentInstance();
                context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_INFO,
                    "Sucessful", "New user has been created!"));

             }
        } catch (Exception e) {
        }

        return toReturn;
    }

    /*
     * Create list group for user can choose to edit
     * warning !!!! this feature it can posible for administrator
     */

     public javax.faces.model.SelectItem[] getGrouplist(){
        SelectItem[] options = null;
        List<Igroup> lGroups = userSessionBean.getGroup();
        if(lGroups != null && lGroups.size() > 0){
            int i = 0 ;
            options = new SelectItem[lGroups.size()];
            for (Igroup iGroup : lGroups){
                options[i++] = new SelectItem(iGroup.getGId(), iGroup.getGName());
            }
        }
        return options;
     }


}

人脸配置

<?xml version='1.0' encoding='UTF-8'?>

<!-- =========== FULL CONFIGURATION FILE ================================== -->

<faces-config version="2.0"
    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_2_0.xsd">
    <managed-bean>
        <description>Controller for enntire User module</description>
        <managed-bean-name>userController</managed-bean-name>
        <managed-bean-class>com.demo.controller.UserController</managed-bean-class>
        <managed-bean-scope>request</managed-bean-scope>
    </managed-bean>
</faces-config>

第二个问题是我没有将组表放入带有 h:selectOne 的组合框

<h:outputLabel value="Igroup:" for="igroup" />
                    <h:selectOneMenu id="igroup" value="#{userController.user.igroup}" title="Igroup" required="true" requiredMessage="The Igroup field is required.">
                        <!-- TODO: update below reference to list of available items-->
                        <f:selectItems value="#{userController.grouplist}"/>
                    </h:selectOneMenu>

当我使用错误发生时，我不知道为什么会发生错误？我从 JSFManageBean 编写 getGrouplist 并在数据库中拥有 1 个方法 getAllGroup Current 的表。

Answer 1

嘿，我刚刚遇到了一个非常相似的问题，并从 Google 偶然发现了这个问题。我通过在您将其映射到的 ManagedBean 中创建一个空数据对象来修复它，在您的情况下会更正

"私人 Iuser 用户；"

到

"私有 Iuser 用户 = new Iuser();"

在 UserController 类中。

由于我自己对 EE 还很陌生，我无法真正解释原因，但它对我有所帮助并希望它也能解决您的问题...

Answer 2

request 范围意味着在每次请求时都会重新创建您的控制器，并且原始值会丢失。除了该注释之外，您还可以在 JSF 2.0 中使用注释。所以你可以放

@ViewScoped
@ManagedBean
public class UserController {..}

请参阅this 了解更多信息。

Answer 3

您必须为“组”创建一个转换器类，以便在 selectOnemenu 中使用，如本例

selectonemenu jsf on objects with converter`

并像这样使用：

  <h:selectOneMenu id="igroup" value="#{userController.user.igroup}" title="Igroup"                         required="true" requiredMessage="The Igroup field is required.">
                        <!-- TODO: update below reference to list of available items-->
                        <f:selectItems value="#{userController.grouplist}"/>
                      <f:converter converterId="groupConverter" />
                    </h:selectOneMenu>

Answer 4

在您的 ManagedBean 中，而不是在下面：

private UserSessionBean userSessionBean = new UserSessionBean;

然后解决它。