Getting ClassCastException while accessing ServletRequest object.

Question

Hi,
I am using weblogic 8.1 sp4 and I am trying to deploy a JSF portal application. When I try to access ServletRequest object, it throws a ClassCastException.
code snippet -
ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
ServletRequest servletRequest = (ServletRequest)externalContext.getRequest(); // Throws error at this point.
It works fine if I use PortletRequest instead of ServletRequest. But I am trying to make it independent of portal API. Is there any way by which I can access servletRequest object?
If I run this application outside portal environment(i.e. only on JSF fraemwork), it works fine.
Here is the error i get in my browser -
javax.portlet.PortletException: Error Invoking Method '#{ValidateServlet.Validate}' : java.lang.ClassCastException at com.sun.faces.portlet.FacesPortlet.processAction(FacesPortlet.java:236) at com.bea.portlet.container.PortletStub.processAction(PortletStub.java:277) at com.bea.portlet.container.AppContainer.invokeProcessAction(AppContainer.java:428) at com.bea.netuix.servlets.controls.content.JavaPortletContent.fireProcessAction(JavaPortletContent.java:202) at com.bea.netuix.servlets.controls.portlet.JavaPortlet.fireProcessAction(JavaPortlet.java:1091) at com.bea.netuix.servlets.controls.portlet.JavaPortlet.raiseChangeEvents(JavaPortlet.java:566) at com.bea.netuix.nf.ControlLifecycle$4.postVisitRoot(ControlLifecycle.java:298) at com.bea.netuix.nf.ControlTreeWalker.walkRecursive(ControlTreeWalker.java:315) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:127) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:106) at com.bea.netuix.nf.Lifecycle.runInbound(Lifecycle.java:173) at com.bea.netuix.nf.Lifecycle.run(Lifecycle.java:137) at com.bea.netuix.servlets.manager.UIServlet.runLifecycle(UIServlet.java:321) at com.bea.netuix.servlets.manager.UIServlet.doPost(UIServlet.java:184) at com.bea.netuix.servlets.manager.PortalServlet.doPost(PortalServlet.java:767) at com.bea.netuix.servlets.manager.UIServlet.service(UIServlet.java:138) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1006) at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419) at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:28) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27) at com.bea.p13n.servlets.PortalServletFilter.doFilter(PortalServletFilter.java:293) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27) at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6724) at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121) at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3764) at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2644) at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219) at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178) Caused by: javax.faces.el.EvaluationException: Error Invoking Method '#{ValidateServletJ.Validate}' : java.lang.ClassCastException at com.sun.faces.el.MethodBindingImpl.rethrow(MethodBindingImpl.java:109) at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:101) at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:72) at javax.faces.component.UICommand.broadcast(UICommand.java:312) at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:267) at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:381) at com.sun.faces.portlet.LifecycleImpl$InvokeApplicationPhase.execute(LifecycleImpl.java:524) at com.sun.faces.portlet.LifecycleImpl.phase(LifecycleImpl.java:246) at com.sun.faces.portlet.LifecycleImpl.execute(LifecycleImpl.java:156) at com.sun.faces.portlet.FacesPortlet.processAction(FacesPortlet.java:222) ... 29 more Caused by: java.lang.ClassCastException at work.ValidateServletJ.Validate(ValidateServletJ.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:324) at com.sun.faces.el.impl.MethodInvokeVisitor.handleMethod(MethodInvokeVisitor.java:44) at com.sun.faces.el.impl.MethodAbstractVisitor.visit(MethodAbstractVisitor.java:354) at com.sun.faces.el.impl.AstValue.jjtAccept(AstValue.java:16) at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:93) ... 37 more Nested Exception is javax.faces.el.EvaluationException: Error Invoking Method '#{ValidateServletJ.Validate}' : java.lang.ClassCastException at com.sun.faces.el.MethodBindingImpl.rethrow(MethodBindingImpl.java:109) at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:101) at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:72) at javax.faces.component.UICommand.broadcast(UICommand.java:312) at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:267) at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:381) at com.sun.faces.portlet.LifecycleImpl$InvokeApplicationPhase.execute(LifecycleImpl.java:524) at com.sun.faces.portlet.LifecycleImpl.phase(LifecycleImpl.java:246) at com.sun.faces.portlet.LifecycleImpl.execute(LifecycleImpl.java:156) at com.sun.faces.portlet.FacesPortlet.processAction(FacesPortlet.java:222) at com.bea.portlet.container.PortletStub.processAction(PortletStub.java:277) at com.bea.portlet.container.AppContainer.invokeProcessAction(AppContainer.java:428) at com.bea.netuix.servlets.controls.content.JavaPortletContent.fireProcessAction(JavaPortletContent.java:202) at com.bea.netuix.servlets.controls.portlet.JavaPortlet.fireProcessAction(JavaPortlet.java:1091) at com.bea.netuix.servlets.controls.portlet.JavaPortlet.raiseChangeEvents(JavaPortlet.java:566) at com.bea.netuix.nf.ControlLifecycle$4.postVisitRoot(ControlLifecycle.java:298) at com.bea.netuix.nf.ControlTreeWalker.walkRecursive(ControlTreeWalker.java:315) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:127) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:106) at com.bea.netuix.nf.Lifecycle.runInbound(Lifecycle.java:173) at com.bea.netuix.nf.Lifecycle.run(Lifecycle.java:137) at com.bea.netuix.servlets.manager.UIServlet.runLifecycle(UIServlet.java:321) at com.bea.netuix.servlets.manager.UIServlet.doPost(UIServlet.java:184) at com.bea.netuix.servlets.manager.PortalServlet.doPost(PortalServlet.java:767) at com.bea.netuix.servlets.manager.UIServlet.service(UIServlet.java:138) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1006) at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419) at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:28) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27) at com.bea.p13n.servlets.PortalServletFilter.doFilter(PortalServletFilter.java:293) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27) at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6724) at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121) at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3764) at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2644) at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219) at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178) Caused by: java.lang.ClassCastException at work.ValidateServletJ.Validate(ValidateServletJ.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:324) at com.sun.faces.el.impl.MethodInvokeVisitor.handleMethod(MethodInvokeVisitor.java:44) at com.sun.faces.el.impl.MethodAbstractVisitor.visit(MethodAbstractVisitor.java:354) at com.sun.faces.el.impl.AstValue.jjtAccept(AstValue.java:16) at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:93) ... 37 more
Any pointers will be greatly appreciated.
Thanks
Kunal

Answer 1

Kunal,
A PortletRequest/RenderRequest is not a ServletRequest - the two are not the same and don't share a common superclass or interface other than java.lang.Object. So simple casting like you're doing won't work.
Are you trying to call a method that is only found on ServletRequest and not on PortletRequest/RenderRequest. If so, you're out of luck. You don't have a ServletRequest object inside the portal, so you can't call methods that aren't on the RenderResponse object.
If the method(s) you're calling are common to both classes then you can use reflection to access the desired methods and avoid a CCE. A good pattern for this type of situation is "Duck Typing" - a description of Duck Typing in Java can be found here:
http://www.coconut-palm-software.com/the_visual_editor/?p=25
Hope that's helpful.
Regards,
Peter