我正在开发一个具有以下内容的 Web 应用程序：
- Glassfish v3.1.2
- 日食朱诺 SR2
- JPA EclipseLink2.0
- JSF 2.0
对于普通用户和管理员用户，我有不同的页面集。在登录期间尝试设置页面过滤器时，我在登录 bean 中收到此错误：javax.faces.FacesException: #{loginBean.login}: java.lang.NullPointerException
没有这部分，我的整个登录代码都可以工作
if (uGDB.validateGroup(username, adminGroup)) {
return "home.jsf?faces-redirect=true&includeViewParams=true";
}
return "normalHome.jsf?faces-redirect=true&includeViewParams=true"
;
我在这里要做的是获取正在登录的用户的组 ID 并检查它是否是管理员。因此，我想将用户引导到相应的页面。这是因为我为管理员用户和普通用户设置了不同的页面。我不想使用 Glassfish 领域，因为最终用户不需要它。
有人可以帮我确定我在哪里出错了。（请原谅我的愚蠢错误，我刚刚开始进行这样的开发）。提前非常感谢！
下面是我的 loginBean 的代码
package beans;
import java.io.Serializable;
import javax.ejb.EJB;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;
import ejb.UserDaoBean;
import ejb.UserGroupDaoBean;
import model.User;
@ManagedBean(name = "loginBean")
@RequestScoped
public class LoginBean implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
@EJB
private UserDaoBean uDB;
private UserGroupDaoBean uGDB;
private User userId;
private int adminGroup = 1;
private String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String login() {
FacesContext context = FacesContext.getCurrentInstance();
if (uDB.validateUser(username)) {
userId = uDB.findUser(username);
context.getExternalContext().getSessionMap().put("userId", userId);
if (uGDB.validateGroup(username, adminGroup)) {
return "home.jsf?faces-redirect=true&includeViewParams=true";
}
return "normalHome.jsf?faces-redirect=true&includeViewParams=true";
} else {
FacesMessage message = new FacesMessage();
message.setSeverity(FacesMessage.SEVERITY_ERROR);
message.setSummary("Username doesn't exists! OR User is trying to login from someone else's account");
context.addMessage("", message);
return null;
}
}
public String logout() {
FacesContext.getCurrentInstance().getExternalContext()
.invalidateSession();
return "logout.jsf?faces-redirect=true";
}
}
这是 Glassfish 日志中的完整错误堆栈
WARNING: #{loginBean.login}: java.lang.NullPointerException
javax.faces.FacesException: #{loginBean.login}: java.lang.NullPointerException
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
... 31 more
Caused by: java.lang.NullPointerException
at beans.LoginBean.login(LoginBean.java:49)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.sun.el.parser.AstValue.invoke(AstValue.java:254)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:302)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 32 more
这是我的控制器类
package ejb;
import java.util.List;
import javax.ejb.LocalBean;
import javax.ejb.Stateful;
import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.Query;
import javax.persistence.PersistenceContext;
import model.Group;
import model.User;
import model.UserGroup;
@Stateful
@LocalBean
public class UserGroupDaoBean {
@PersistenceContext(unitName = "myPU")
private EntityManager entityManager;
public UserGroupDaoBean() {
}
public UserGroup createNewUserGroup(int groupId, String username) {
UserGroup newUserGrp = new UserGroup();
User myUsr;
myUsr = entityManager.find(User.class, username);
newUserGrp.setUser(myUsr);
Group myGrp;
myGrp = entityManager.find(Group.class, groupId);
newUserGrp.setGroup(myGrp);
saveNewUsrGrp(newUserGrp);
return newUserGrp;
}
private void saveNewUsrGrp(UserGroup usrGrp) {
entityManager.persist(usrGrp);
entityManager.flush();
}
public boolean checkUsertoGroup(String username, int groupId) {
Group chkGrp;
chkGrp = entityManager.find(Group.class, groupId);
User chkUsr;
chkUsr = entityManager.find(User.class, username);
if (chkGrp != null) {
if (chkUsr != null) {
try {
entityManager.createNamedQuery("findGroupsbyUser")
.setParameter("username", chkUsr)
.setParameter("groupId", chkGrp).getSingleResult();
System.out.println("UserGroup already exists");
return false;
} catch (NoResultException e) {
return true;
}
}
System.out.println("User doesn't exist");
return false;
}
System.out.println("Group doesn't exist");
return false;
}
public void deleteUserGroup(UserGroup userGroup) {
userGroup = entityManager.merge(userGroup);
entityManager.remove(userGroup);
}
public UserGroup update(UserGroup myUserGroup) {
return entityManager.merge(myUserGroup);
}
@SuppressWarnings("unchecked")
public List<UserGroup> getAllUserGroups() {
try {
Query query = entityManager.createNamedQuery("findAllUserGroup");
List<UserGroup> result = (List<UserGroup>) query.getResultList();
return result;
} catch (NoResultException e) {
System.out.println("No Result found");
return null;
}
}
public boolean validateGroup(String username, int groupId) {
try {
UserGroup myGroupId = (UserGroup) entityManager
.createNamedQuery("findGroup")
.setParameter("username", username)
.setParameter("groupId", groupId).getSingleResult();
if (myGroupId != null) {
System.out.println("This user is admin!!!");
return true;
}
} catch (NoResultException e) {
return false;
}
System.out.println("This user is not admin");
return false;
}
}
下面是我的实体用户组
package model;
import java.io.Serializable;
import javax.persistence.*;
/**
* The persistent class for the UserGroup database table.
*
*/
@NamedQueries({
@NamedQuery(name = "findGroupsbyUser", query = "Select ug.group from UserGroup ug where ug.user=:username AND ug.group=:groupId"),
@NamedQuery(name = "findAllUserGroup", query="Select ug from UserGroup ug"),
@NamedQuery(name = "findAdminGroupId", query = "Select ug from UserGroup ug where ug.user=:username AND ug.group=:groupId"),
})
@Entity
@Table(name="usergroup")
public class UserGroup implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="RowId" )
private int rowId;
//bi-directional many-to-one association to Group
@ManyToOne
@JoinColumn(name="groupId")
private Group group;
//bi-directional many-to-one association to User
@ManyToOne
@JoinColumn(name="username")
private User user;
public UserGroup() {
}
public int getRowId() {
return this.rowId;
}
public void setRowId(int rowId) {
this.rowId = rowId;
}
public Group getGroup() {
return this.group;
}
public void setGroup(Group group) {
this.group = group;
}
public User getUser() {
return this.user;
}
public void setUser(User user) {
this.user = user;
}
}