使用EL訪問繼承屬性/方法時出錯

我正在嘗試使用通用樹支持bean來工作。我有一個名爲ACLTree的泛型類，然後是它的一個實現。在我的JSF文檔中，我嘗試訪問每個＃{mybackingbean.property}的值。但我得到一個ELException：使用EL訪問繼承屬性/方法時出錯

javax.el.ELException: /modules/useradmin/acl.xhtml @30,55 value="#{ACOTree.root}": java.lang.IllegalAccessException: Class javax.el.BeanELResolver can not access a member of class de.xy.jsf.beans.ACLTree with modifiers "public"

我不是很熟悉泛型和反射API的概念，所以也許這是根本不可能的。

堆棧跟蹤：

javax.faces.FacesException: javax.el.ELException: /modules/useradmin/rights.xhtml @30,55 value="#{ACOTree.root}": java.lang.IllegalAccessException: Class javax.el.BeanELResolver can not access a member of class de.xy.jsf.beans.ACLTree with modifiers "public" 
     at javax.faces.component.UIData.getValue(UIData.java:580) 
     at org.ajax4jsf.component.UIDataAdaptorBase.getValue(UIDataAdaptorBase.java:1647) 
     at org.richfaces.component.UITree.createDataModel(UITree.java:679) 
     at org.ajax4jsf.component.UIDataAdaptorBase.getExtendedDataModel(UIDataAdaptorBase.java:621) 
     at org.ajax4jsf.component.UIDataAdaptorBase.setRowKey(UIDataAdaptorBase.java:339) 
     at org.richfaces.renderkit.TreeRendererBase.writeContent(TreeRendererBase.java:688) 
     at org.richfaces.renderkit.TreeRendererBase.encodeChildren(TreeRendererBase.java:629) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:277) 
     at org.ajax4jsf.renderkit.RendererBase.renderChildren(RendererBase.java:258) 
     at org.richfaces.renderkit.html.PanelRenderer.doEncodeChildren(PanelRenderer.java:200) 
     at org.richfaces.renderkit.html.PanelRenderer.doEncodeChildren(PanelRenderer.java:195) 
     at org.ajax4jsf.renderkit.RendererBase.encodeChildren(RendererBase.java:120) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:233) 
     at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:270) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at javax.faces.component.UIComponent.encodeAll(UIComponent.java:883) 
     at javax.faces.render.Renderer.encodeChildren(Renderer.java:137) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:277) 
     at org.ajax4jsf.renderkit.RendererBase.renderChildren(RendererBase.java:258) 
     at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:279) 
     at org.ajax4jsf.renderkit.RendererBase.renderChildren(RendererBase.java:258) 
     at org.richfaces.renderkit.TabRendererBase.encodeChildren(TabRendererBase.java:149) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:277) 
     at org.ajax4jsf.renderkit.RendererBase.renderChildren(RendererBase.java:258) 
     at org.richfaces.renderkit.html.TabPanelRenderer.doEncodeChildren(TabPanelRenderer.java:266) 
     at org.richfaces.renderkit.html.TabPanelRenderer.doEncodeChildren(TabPanelRenderer.java:261) 
     at org.ajax4jsf.renderkit.RendererBase.encodeChildren(RendererBase.java:120) 
     at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:827) 
     at javax.faces.component.UIComponent.encodeAll(UIComponent.java:883) 
     at javax.faces.component.UIComponent.encodeAll(UIComponent.java:889) 
     at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:578) 
     at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100) 
     at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176) 
     at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:108) 
     at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:266) 
     at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:159) 
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:245) 
     at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523) 
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343) 
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) 
     at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:206) 
     at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290) 
     at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388) 
     at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515) 
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) 
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) 
     at cz.softeu.rewriter.RewriterFilter.doFilter(RewriterFilter.java:144) 
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) 
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) 
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:277) 
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) 
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) 
     at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) 
     at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) 
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) 
     at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325) 
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226) 
     at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) 
     at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) 
     at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) 
     at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) 
     at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) 
     at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) 
     at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) 
     at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) 
     at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) 
     at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) 
     at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) 
     at com.sun.grizzly.ContextTask.run(ContextTask.java:69) 
     at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) 
     at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) 
     at java.lang.Thread.run(Thread.java:636) 
Caused by: javax.el.ELException: /modules/useradmin/rights.xhtml @30,55 value="#{ACOTree.root}": java.lang.IllegalAccessException: Class javax.el.BeanELResolver can not access a member of class de.christianvette.boombox.jsf.beans.ACLTree with modifiers "public" 
     at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:76) 
     at javax.faces.component.UIData.getValue(UIData.java:577) 
     ... 75 more 
Caused by: java.lang.IllegalAccessException: Class javax.el.BeanELResolver can not access a member of class de.xy.jsf.beans.ACLTree with modifiers "public" 
     at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:95) 
     at java.lang.reflect.Method.invoke(Method.java:607) 
     at javax.el.BeanELResolver.getValue(BeanELResolver.java:302) 
     at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175) 
     at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:58) 
     at com.sun.el.parser.AstValue.getValue(Unknown Source) 
     at com.sun.el.ValueExpressionImpl.getValue(Unknown Source) 
     at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71) 
     ... 76 more

泛型類：

abstract class ACLTree<T>{ 
private static final Logger log = Logger.getLogger(ACLTree.class); 

public TreeNodeImpl<NodeData> root = null; 
public TreeNodeImpl<NodeData> nodes = new TreeNodeImpl<NodeData>(); 

public ACLTree() { 
    log.debug("constructor of generic class"); 
} 

public TreeNodeImpl<NodeData> getNodes() { 
    return nodes; 
} 

public void setNodes(TreeNodeImpl<NodeData> nodes) { 
    this.nodes = nodes; 
} 

public TreeNodeImpl<NodeData> getRoot() { 
    log.debug("Entering getRoot()"); 
    if(root == null) buildTree(); 
    return root; 
} 

public void setRoot(TreeNodeImpl root) { 
    this.root = root; 
} 

public TreeNodeImpl createTreeNode(ACLObject item) { 

} 

abstract Collection<T> getData();

}

實現：

public class ACOTree extends ACLTree<ACO>{ 

    @Override 
    public Collection<ACO> getData() { 
     return AclManagerImpl.getInstance().getAllACOs(); 
    } 
}

來源

2010-07-18 Chris

什麼是ACOTree定義爲？它試圖訪問的財產是否有吸氣？（即'root'） – casablanca 2010-07-18 23:38:28

ACOTree擴展了名爲ACLTree的泛型類，因此getter和setter在泛型類中定義（公共），並且只在ACOTree中繼承。 – Chris 2010-07-18 23:51:22

您正在使用哪種EL實現/版本？或者，如果您沒有使用特定版本，您使用的是哪個servletcontainer impl/version？如果您還不知道，只需更新您的問題以包含完整的堆棧跟蹤。 – BalusC 2010-07-19 01:07:35

我碰到這個問題我自己。問題是抽象類的聲明必須是公開的。

例如：

public abstract class ACLTree<T>{...}

這是因爲雖然抽象類的方法可以是公它不能被從包裝外面，除非類被標記公衆以及訪問。

來源

2012-02-04 17:17:08 klonq

我遇到了同樣的問題，找到解決方案非常簡單，非常放心。謝謝。 – 2012-02-14 07:51:25

4小時，此時我已經失去了4個小時，並最終解決 - 謝謝！ – 2015-08-18 10:15:53

使用EL訪問繼承屬性/方法時出錯

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