使用JSF2的Spring依赖注入中的空指针异常

时间：2013-05-19 14:46:35

标签： spring jsf-2 dependency-injection null

我正在使用jsf2和spring作为DI。当我从页面发出请求时，我得到NullPointer异常。意味着自动装配不起作用。

我正在接受以下错误。 follwing是我的整个服务器日志。

May 19, 2013 8:10:44 PM org.apache.catalina.startup.HostConfig deployDescriptor
INFO: Deploying configuration descriptor C:\Users\kshitij\AppData\Roaming\NetBeans\7.3\apache-tomcat-7.0.34.0_base\conf\Catalina\localhost\Spirng_jsf.xml
May 19, 2013 8:10:47 PM org.springframework.web.context.ContextLoader initWebApplicationContext
INFO: Root WebApplicationContext: initialization started
May 19, 2013 8:10:47 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing Root WebApplicationContext: startup date [Sun May 19 20:10:47 IST 2013]; root of context hierarchy
May 19, 2013 8:10:47 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from ServletContext resource [/WEB-INF/beans.xml]
May 19, 2013 8:10:47 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@34ab7a: defining beans [myBean,userdaoImpl,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor#0]; root of factory hierarchy
May 19, 2013 8:10:47 PM org.springframework.web.context.ContextLoader initWebApplicationContext
INFO: Root WebApplicationContext: initialization completed in 714 ms
May 19, 2013 8:10:47 PM com.sun.faces.config.ConfigureListener contextInitialized
INFO: Initializing Mojarra 2.1.13 ( 20120907-1514) for context '/Spirng_jsf'
May 19, 2013 8:10:47 PM com.sun.faces.spi.InjectionProviderFactory createInstance
INFO: JSF1048: PostConstruct/PreDestroy annotations present.  ManagedBeans methods marked with these annotations will have said annotations processed.
May 19, 2013 8:10:48 PM org.apache.catalina.util.LifecycleBase start
INFO: The start() method was called on component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Spirng_jsf]] after start() had already been called. The second call will be ignored.
May 19, 2013 8:11:34 PM javax.faces.component.UIViewRoot$ViewMap put
WARNING: Setting non-serializable attribute value into ViewMap: (key: myBean, value class: com.ksh.excel.MyBean)
May 19, 2013 8:11:34 PM com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: #{myBean.kshitij}: java.lang.NullPointerException
javax.faces.FacesException: #{myBean.kshitij}: java.lang.NullPointerException
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:117)
    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.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    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:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    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:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
    at java.lang.Thread.run(Thread.java:619)
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:101)
    ... 26 more
Caused by: java.lang.NullPointerException
    at com.ksh.excel.MyBean.kshitij(MyBean.java:26)
    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:278)
    at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
    ... 27 more

我的界面。

package com.ksh.excel;
import org.springframework.stereotype.Component;
@Component
public interface Userdao {    
    public void print();
}

接口实施

package com.ksh.excel;
import org.springframework.stereotype.Component;
@Component
public class UserdaoImpl implements Userdao {

    @Override
    public void print() 
    {
        System.out.println("Kshitij ***********************************");
    }

}

和JSF托管Bean 

package com.ksh.excel;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@ManagedBean
@ViewScoped
@Component
public class MyBean {

    @Autowired
    private Userdao userdao;

    public String kshitij()
    {
        userdao.print();
        return null;
    }
}

1 个答案:

答案 0 :(得分：1)

从@Component界面中删除Userdao。并且还添加

<context:component-scan base-package="com.ksh.excel" />

在applicationContext.xml中。如果您之前没有添加它。有关详细信息，请查看here。

干杯！

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