异常 - 无法为托管Bean凭据设置属性userLogin

Question

为了进行身份验证，我将请求作用域支持bean注入到另一个要存储已记录用户的会话作用域bean中。或者至少应该...... 之后，一些代码：

请求范围豆 - 托管属性

@ManagedProperty(value="userLogin") 

错误 无法设置属性USERLOGIN为托管bean凭据

堆栈跟踪

com.sun.faces.mgbean.ManagedBeanCreationException: Unable to set property userLogin for managed bean credentials 
at com.sun.faces.mgbean.ManagedBeanBuilder$BakedBeanProperty.set(ManagedBeanBuilder.java:615) 
at com.sun.faces.mgbean.ManagedBeanBuilder.buildBean(ManagedBeanBuilder.java:133) 
at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:104) 
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:244) 
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:116) 
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:72) 
at org.apache.el.parser.AstValue.getValue(AstValue.java:161) 
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:185) 
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109) 
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194) 
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182) 
at javax.faces.component.UIOutput.getValue(UIOutput.java:169) 
at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205) 
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:355) 
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164) 
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875) 
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312) 
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185) 
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129) 
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845) 
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779) 
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168) 
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845) 
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779) 
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782) 
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782) 
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:437) 
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:124) 
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:139) 
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594) 
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: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$SocketProcessor.run(JIoEndpoint.java:312) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
at java.lang.Thread.run(Unknown Source) 
Caused by: javax.el.ELException: Cannot convert userLogin of type class java.lang.String to class model.businessLogic.UserLogin 
at org.apache.el.lang.ELSupport.coerceToType(ELSupport.java:420) 
at org.apache.el.ExpressionFactoryImpl.coerceToType(ExpressionFactoryImpl.java:47) 
at com.sun.faces.el.ELUtils.coerce(ELUtils.java:536) 
at com.sun.faces.mgbean.BeanBuilder$Expression.evaluate(BeanBuilder.java:592) 
at com.sun.faces.mgbean.ManagedBeanBuilder$BakedBeanProperty.set(ManagedBeanBuilder.java:606) 
... 51 more 

Answer 1

阅读异常的根本原因，了解原因（和固有从而也解决）：

产生的原因：javax.el.E​​LException：无法将类型类java.lang.String中的用户登陆到类model.businessLogic.UserLogin

因此，你引用一个String实例为管理bean，而不是UserLogin实例。

事实上，你的托管属性值无效：

@ManagedProperty(value="userLogin") 

它引用一个普通的String。你需要引用，而不是一个托管bean：

@ManagedProperty(value="#{userLogin}") 

或者更短，因为value attribtue是注释的默认属性：

@ManagedProperty("#{userLogin}")