当我尝试通过以下xhtml中的代码访问托管bean的登录方法时：
<p:commandButton value="Login" actionListener="#{login.log}" styleClass="btn btn-danger btn-lg btn-block" update="growl"/>
我的Login类看起来像这样：
@ManagedBean(name = "login")
@ViewScoped
public class LoginBean implements Serializable {
private static final long serialVersionUID = 1L;
@ManagedProperty("#{userImpService}")
private UserImpService userImpService;
public UserImpService getUserImpService() {
return userImpService;
}
public void setUserImpService(
UserImpService userImpService) {
this.userImpService = userImpService;
}
private String userName;
private String passWord;
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 void log(ActionEvent event) {
if (getUserName().equals(""))
FacesContext.getCurrentInstance().addMessage(
null,
new FacesMessage(FacesMessage.SEVERITY_ERROR, "erreur!",
"champ identifient vide "));
if (getPassWord().equals(""))
FacesContext.getCurrentInstance().addMessage(
null,
new FacesMessage(FacesMessage.SEVERITY_WARN, "erreur!",
"champ mot de passe vide "));
FacesContext.getCurrentInstance().addMessage(
null,
new FacesMessage(FacesMessage.SEVERITY_ERROR, "erreur!",
"identifient et mot de passe invalide "));
System.out.println("Etape JSF .................... Che");
boolean b = userImpService.searchProfil("","");
}
当我调用boolean b = userImpService.searchProfil（“”，“”）;它给了我以下错误：
com.sun.faces.lifecycle.InvokeApplicationPhase execute
AVERTISSEMENT: /views/login.xhtml @70,132 actionListener="#{login.log}": java.lang.NullPointerException
javax.el.ELException: /views/login.xhtml @70,132 actionListener="#{login.log}": java.lang.NullPointerException
at com.sun.faces.facelets.el.TagMethodExpression.invoke(Unknown Source)
at javax.faces.event.MethodExpressionActionListener.processAction(Unknown Source)
at javax.faces.event.ActionEvent.processListener(Unknown Source)
at javax.faces.component.UIComponentBase.broadcast(Unknown Source)
at javax.faces.component.UICommand.broadcast(Unknown Source)
at javax.faces.component.UIViewRoot.broadcastEvents(Unknown Source)
at javax.faces.component.UIViewRoot.processApplication(Unknown Source)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(Unknown Source)
at com.sun.faces.lifecycle.Phase.doPhase(Unknown Source)
at com.sun.faces.lifecycle.LifecycleImpl.execute(Unknown Source)
at javax.faces.webapp.FacesServlet.service(Unknown Source)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at primefaces.presentation.LoginBean.log(LoginBean.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:273)
... 31 more
nov. 29, 2015 4:02:42 PM com.sun.faces.context.AjaxExceptionHandlerImpl handlePartialResponseError
GRAVE: java.lang.NullPointerException
at primefaces.presentation.LoginBean.log(LoginBean.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:273)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(Unknown Source)
at javax.faces.event.MethodExpressionActionListener.processAction(Unknown Source)
at javax.faces.event.ActionEvent.processListener(Unknown Source)
at javax.faces.component.UIComponentBase.broadcast(Unknown Source)
at javax.faces.component.UICommand.broadcast(Unknown Source)
at javax.faces.component.UIViewRoot.broadcastEvents(Unknown Source)
at javax.faces.component.UIViewRoot.processApplication(Unknown Source)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(Unknown Source)
at com.sun.faces.lifecycle.Phase.doPhase(Unknown Source)
at com.sun.faces.lifecycle.LifecycleImpl.execute(Unknown Source)
at javax.faces.webapp.FacesServlet.service(Unknown Source)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)