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我在尝试运行 Spring-jsf 应用程序时遇到 javax.faces.el.E​​valuationException: java.lang.NullPointerException 错误。我尝试调试代码，发现“serviceIfc”没有被初始化并且为空，我无法弄清楚如何解决它。请帮忙。这是我的 LoginBean.java 

@ManagedBean
public class LoginBean {
private String uname;
private String pwd;
private LoginServiceIfc serviceIfc;

public LoginServiceIfc getServiceIfc() {
return serviceIfc;
}
@Autowired
    public void setServiceIfc(LoginServiceIfc serviceIfc) {
this.serviceIfc = serviceIfc;
System.out.println("setServiceIfc method inside LOginBean running...");
}

public String getUname() {
    return uname;
}

public void setUname(String uname) {
    this.uname = uname;
}

public String getPwd() {
    return pwd;
}

public void setPwd(String pwd) {
    this.pwd = pwd;
}

public String doLogin()
{
    if(uname=="" || pwd=="")
    {
        return "fail";
    }
    else
    {
        String str=serviceIfc.doLogin(uname,pwd);
        return str;
    }
}

}

applicationcontext.xml 的一部分如下：

<bean id="loginBean" class="com.bean.LoginBean" scope="session">
<property name="serviceIfc">
    <ref bean="loginServiceIfc" />
</property>      
</bean>

<bean id="loginServiceIfc" class="com.service.serviceImpl.login.LoginServiceImpl" scope="session">
<property name="daoIfc">
    <ref bean="loginDaoIfc" />
</property>
</bean>

<bean id="loginDaoIfc" class="com.dao.daoImpl.login.LoginDaoImpl" scope="session">
</bean>

以下是完整的错误消息：

Apr 25, 2013 1:36:14 AM com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: #{loginBean.doLogin}: java.lang.NullPointerException
javax.faces.FacesException: #{loginBean.doLogin}: 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 com.controller.LoginServlet.service(LoginServlet.java:34)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
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)
... 25 more
Caused by: java.lang.NullPointerException
at com.bean.LoginBean.doLogin(LoginBean.java:46)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.el.parser.AstValue.invoke(AstValue.java:264)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 26 more
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1 回答 1

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您使用的两个框架中的注释不能一起使用。要么让 JSF 使用@ManagedBean/管理 bean，要么让@ManagedPropertySpring 使用@Component/管理 bean @Autowired。

您现在拥有它的方式无法执行依赖注入，因此NullPointerException您面临。

于 2013-04-24T20:57:34.117 回答