javax.servlet.ServletException - how could i get to the cause?

Question

Hi,

i'm getting a very strange error while opening one of the pages in my web app. The application is built on Seam 2.2 and is using JSF (RichFaces) in the presentation layer. I run it on Tomcat 6.

In logs everything looks fine - each next JSF Phase executes normally, and after the last one, there is this moment when the request starts processing for the SEAM debug page...

And this is the stack trace i see on the debug page (nothing is logged):

Exception during request processing: Caused by javax.servlet.ServletException with message: "Servlet execution threw an exception"

org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:313)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)
org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388)
org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515)
org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53)
org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
pl.mgibowski.alterium.util.LoggingFilter.doFilter(LoggingFilter.java:18)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:465)
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:619)

Exception without any cause...

I was trying to catch the exception with my custom Filter (LoggingFilter.java that you can see on the strack trace), using this code:

try {
            filterChain.doFilter(servletRequest, servletResponse);
        }
        catch (Throwable e) {
            e.printStackTrace();
            System.out.println("Stack trace:");
            System.out.println(e.getStackTrace());
            System.out.println("Cause:");
            System.out.println(e.getCause());
        }

But it doesn't catch anything, the line 18 from the stack trace is this one:

filterChain.doFilter(servletRequest, servletResponse);

nothing gets caught by the try block.

Anybody has any ideas about how could i get closer to the real cause?

Answer 1

Ok, i have changed the order in which my filter and my filter mapping appers in web.xml and now my filter is catching the real exception.