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Libra2880
Asked: 2020-01-09 07:03:12 +0800 CST 2020-01-09 07:03:12 +0800 CST

com.sun.faces.mgbean.ManagedBeanCreationException：

  • 772

你好。产生这个错误的原因是什么？我只是输入我的代码：

@PostConstruct
public void init(){
    this.listarMenus();
    model=new DefaultMenuModel();
    this.establecerPermisos();

}

它会产生以下错误：

com.sun.faces.mgbean.ManagedBeanCreationException: Se ha producido un error al realizar la inyección de recurso en el bean administrado menuBean
    at com.sun.faces.mgbean.BeanBuilder.invokePostConstruct(BeanBuilder.java:227)
    at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:103)
    at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:409)
    at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:269)
    at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:257)
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:117)
    at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:80)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:137)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
    at org.primefaces.component.menubar.Menubar.getModel(Menubar.java:86)
    at org.primefaces.component.menu.BaseMenuRenderer.encodeEnd(BaseMenuRenderer.java:109)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:919)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2500)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2489)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: com.sun.faces.spi.InjectionProviderException
    at com.sun.faces.vendor.WebContainerInjectionProvider.invokeAnnotatedMethod(WebContainerInjectionProvider.java:115)
    at com.sun.faces.vendor.WebContainerInjectionProvider.invokePostConstruct(WebContainerInjectionProvider.java:95)
    at com.sun.faces.mgbean.BeanBuilder.invokePostConstruct(BeanBuilder.java:221)
    ... 49 more
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.sun.faces.vendor.WebContainerInjectionProvider.invokeAnnotatedMethod(WebContainerInjectionProvider.java:113)
    ... 51 more
Caused by: java.lang.NullPointerException
    at com.proyecto.bean.MenuBean.establecerPermisos(MenuBean.java:58)
    at com.proyecto.bean.MenuBean.init(MenuBean.java:41)
    ... 56 more
java

2 Answers

  1. 该跟踪的最后几行告诉您发生了类型异常java.lang.NullPointerException：

        ... 51更多
引起：com.project.bean.MenuBean.setPermissions(MenuBean.java:58) 处的java.lang.NullPointerException
    
    在 com.project.bean.MenuBean.init(MenuBean.java:41)
    ...56更多

    该方法第 58 行的establecerPermisos内容是null.

    • 1
  2. Best Answer

    以下代码显示了解决方案。

      public List<SubMenu> listar() throws Exception{      
    List<SubMenu> lista;
    ResultSet rs;
    Menu menu=new Menu();        
    SubMenu submenu=new SubMenu();        
    EmpleadoDao dao=new EmpleadoDao();
    dao.listar();               
    try{            
        this.Conectar();      
        PreparedStatement st=this.getCn().prepareCall("select m.idMenu,m.codMenu,m.nomMenu,m.link,m.tipo,m.estadoMenu,s.idSubMenu,s.itemSubMenu,s.nombreSubMenu,s.linkSubMenu,s.estadoSubMenu,s.tipo,s.idMenu from menu m \n" +
                              "                     inner join submenu s on m.idmenu=s.idmenu group by m.nomMenu");       


        rs=st.executeQuery();
        lista=new ArrayList();

        while(rs.next()){                      


            menu.setIdMenu(rs.getInt("m.idMenu"));             
            menu.setCodMenu(rs.getString("m.codMenu"));    
            menu.setNomMenu(rs.getString("nomMenu"));
            menu.setLink(rs.getString("m.link"));
            menu.setTipo(rs.getString("m.tipo"));
            menu.setEstadomenu(rs.getString("m.estadoMenu"));
            submenu.setIdsubmenu(rs.getInt("s.idSubMenu"));
            submenu.setItemsubmenu(rs.getString("s.itemSubMenu"));
            submenu.setNombresubmenu(rs.getString("s.nombreSubMenu"));
            submenu.setLinksubmenu(rs.getString("s.linkSubMenu"));
            submenu.setEstadosubmenu(rs.getString("s.estadoSubMenu"));
            submenu.setTipo(rs.getString("s.tipo"));
            menu.setIdMenu(rs.getInt("s.idMenu"));
            submenu.setMenu(menu);
            lista.add(submenu);  
            //lista3.add(menu);
        }            
    }catch(Exception e){            
        throw e;
    }finally{            
        this.Cerrar();
    }
    return lista;
}
    • 1