我在Netbeans 7.4中创建了一个新的Java EE 6企业应用程序。所以我有三个项目：
EAR
EJB
WAR
为了实现登录功能。我创建了以下内容。
实体bean：Useraccount
package com.wms.entities;
import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;
@Entity
@Table(name = "useraccount")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Useraccount.findAll", query = "SELECT u FROM Useraccount u"),
@NamedQuery(name = "Useraccount.findById", query = "SELECT u FROM Useraccount u WHERE u.id = :id"),
@NamedQuery(name = "Useraccount.findByUsername", query = "SELECT u FROM Useraccount u WHERE u.username = :username"),
@NamedQuery(name = "Useraccount.findByPassword", query = "SELECT u FROM Useraccount u WHERE u.password = :password"),
@NamedQuery(name = "UserAccount.findUseraccount", query = "SELECT a FROM Useraccount a WHERE a.username = :username AND a.password = :password"),
@NamedQuery(name = "Useraccount.findByUserType", query = "SELECT u FROM Useraccount u WHERE u.userType = :userType")})
public class Useraccount implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
private Integer id;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 45)
@Column(name = "username")
private String username;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 45)
@Column(name = "password")
private String password;
@Size(max = 45)
@Column(name = "userType")
private String userType;
public Useraccount() {
}
public Useraccount(Integer id) {
this.id = id;
}
public Useraccount(Integer id, String username, String password) {
this.id = id;
this.username = username;
this.password = password;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
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 String getUserType() {
return userType;
}
public void setUserType(String userType) {
this.userType = userType;
}
@Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.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 Useraccount)) {
return false;
}
Useraccount other = (Useraccount) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.wms.entities.Useraccount[ id=" + id + " ]";
}
}
会话bean：UseraccountManager
package com.wms.sessions;
import com.wms.entities.Useraccount;
import java.util.List;
import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
@Stateless
public class UseraccountManager implements UseraccountManagerRemote{
@PersistenceContext
private EntityManager em;
public List<Useraccount> getAllUseraccount() {
Query query=em.createNamedQuery("Useraccount.findAll");
return query.getResultList();
}
public Useraccount update(Useraccount useraccount) {
return em.merge(useraccount);
}
@Override
public void persist(Object object) {
em.persist(object);
}
public Useraccount find(Useraccount useraccount){
Query query=em.createNamedQuery("Useraccount.findByUsername").setParameter("username", useraccount.getUsername());
List<Useraccount> acts=query.getResultList();
if(acts.isEmpty())
return null;
Useraccount act=acts.get(0);
if(!act.getPassword().equals(useraccount.getPassword()))
return null;
return act;
}
@Override
public String validateUser(String username, String password){
System.out.println("\n\n\nheloooo\n\n\n");
Query query=em.createNamedQuery("Useraccount.findByUsername").setParameter("username", username);
List<Useraccount> acts=query.getResultList();
if(acts.isEmpty())
return "unknown";
Useraccount act=acts.get(0);
if(act.getPassword().equals(password))
return act.getUserType();
return "unknown";
}
}
2.在Web应用程序项目中，我创建了Managed bean（LoginBean）和Login页面（login.xhtml），如下所示 托管bean：LoginBean
package com.wms.managedbeans;
import com.wms.sessions.UseraccountManager;
import java.io.Serializable;
import javax.ejb.EJB;
import javax.enterprise.context.RequestScoped;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.inject.Named;
import javax.servlet.http.HttpSession;
@Named
@RequestScoped
public class LoginBean implements Serializable {
private static final long serialVersionUID = 1L;
private String password;
private String message, username;
private String userType;
@EJB
private UseraccountManager uam;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUsername() {
return username;
}
public void setUsername(String uname) {
this.username = uname;
}
public String getUser() {
System.out.println(Util.getUserId());
return Util.getUserId();
}
public String getUserType(){
HttpSession session = Util.getSession();
if ( session != null )
return (String) session.getAttribute("userType");
else
return null;
}
public String login() {
userType = uam.validateUser(username, password);
HttpSession session = Util.getSession();
if (userType.equals("unknown")){
FacesContext.getCurrentInstance().addMessage(
null,
new FacesMessage(FacesMessage.SEVERITY_WARN,
"Invalid Login!",
"Please Try Again!"));
// invalidate session, and redirect to other pages
//message = "Invalid Login. Please Try Again!";
return "login";
}
else{
// get Http Session and store username
session.setAttribute("username", username);
session.setAttribute("userType",userType);
if (userType.equals("administrator"))
return "admin/adminHome?faces-redirect=true";
else if(userType.equals("warehouseman"))
return "WM/wmHome?faces-redirect=true";
else if(userType.equals("employee"))
return "emp/empHome?faces-redirect=true";
else
return "man/manHome?faces-redirect=true";
}
}
public String logout() {
HttpSession session = Util.getSession();
session.invalidate();
return "/login?faces-redirect=true";
}
}
用户界面：login.xhtml
<ui:composition template="/templates/layout.xhtml"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:p="http://primefaces.org/ui">
<ui:define name="content">
<h:form styleClass="loginPanelStyle">
<p:growl id="msgs" showDetail="true" sticky="false" />
<p:panelGrid columns="2">
<f:facet name="header">
Login Panel
</f:facet>
<h:outputText value="Username : "></h:outputText>
<p:inputText id="username" value="#{loginBean.username}" required="true" requiredMessage="Please Enter Username!">
<f:validateLength minimum="1" />
</p:inputText>
<h:outputText value="Password : "></h:outputText>
<p:password id="password" value="#{loginBean.password}" required="true" requiredMessage="Please Enter password!">
<f:validateLength minimum="1" />
</p:password>
<f:facet name="footer">
<p:commandButton id="Submit" value="Submit" update="msgs" action="#{loginBean.login}" type="submit" icon="ui-icon-check" style="margin:0"></p:commandButton>
</f:facet>
</p:panelGrid>
</h:form>
</ui:define>
</ui:composition>
在我运行Web应用程序时部署项目后，它会显示登录页面，不幸的是，当我插入时，它会生成以下错误
WARNING: /login.xhtml @16,131 value="#{loginBean.username}": Target Unreachable, identifier 'loginBean' resolved to null
javax.el.PropertyNotFoundException: /login.xhtml @16,131 value="#{loginBean.username}": Target Unreachable, identifier 'loginBean' resolved to null
at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:100)
at org.primefaces.renderkit.InputRenderer.findImplicitConverter(InputRenderer.java:170)
at org.primefaces.renderkit.InputRenderer.findConverter(InputRenderer.java:190)
at org.primefaces.renderkit.InputRenderer.getConvertedValue(InputRenderer.java:196)
at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1046)
at javax.faces.component.UIInput.validate(UIInput.java:976)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1249)
at javax.faces.component.UIInput.processValidators(UIInput.java:712)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIForm.processValidators(UIForm.java:253)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at org.primefaces.component.layout.Layout.processValidators(Layout.java:246)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:344)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at filters.AuthFilter.doFilter(AuthFilter.java:44)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:744)
Caused by: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'loginBean' resolved to null
at com.sun.el.parser.AstValue.getTarget(AstValue.java:174)
at com.sun.el.parser.AstValue.getType(AstValue.java:86)
at com.sun.el.ValueExpressionImpl.getType(ValueExpressionImpl.java:201)
at org.jboss.weld.el.WeldValueExpression.getType(WeldValueExpression.java:93)
at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:98)
... 51 more
我是EJB + JSF的新手请帮我解决上述问题
答案 0 :(得分：1)
当我在LoginBean托管bean类中用@ManagedBean（name =“loginBean”）替换@Named注释时，它可以完美地工作。但任何人都可以在这个背景下解释两者之间的区别。感谢Luiggi Medoza的帮助