Thanks for the reply, Craig.
> > Error Trace
> > -----------
> >
> > java.lang.IncompatibleClassChangeError
>
> This exception normally means you have made a change in a superclass and
> recompiled it, but not recompiled a subclass that depends on the old APIs.
mmmmm, I have no idea which class this could be referring
to then, unless it means one of Tomcat's distribution
classes. To further debug, I removed ALL other classes
under "WEB-INF/classes", so that I only have my one Filter
there. I also removed all jars from WEB-INF/lib, then
restarted Tomcat. Therefore, the only superclass involved
is the Filter class.
I recompiled my LanguageFilter.java and yet the error
still occured.
> > at mas.TestFilter.doFilter(Store/LanguageFilter.java:35)
>
> What is "Store"? Is that supposed to be the package name?
Sorry, yes, I copied an earlier/older trace.
> You should recompile *all* your classes to catch any cases
> where you've made incompatible changes.
I've done exactly that now (basically due to the fact that
I only have the ONE class - the LanguageFilter.java)
I have even deleted the entire contents of the "<tomcat_home>/work"
directory and restarted Tomcat again to ensure that it
is not an old class being cached in memory.
Interestingly, the very first time that I make a request to
the Filter, I get the following error message:
<snip>
java.lang.LinkageError: Class javax/servlet/RequestDispatcher violates loader
constraints
at test.LanguageFilter.doFilter(test/LanguageFilter.java:36)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:215)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
</snip>
Yet when I hit "reload" the error message changes to:
<snip>
java.lang.IncompatibleClassChangeError
at test.LanguageFilter.doFilter(test/LanguageFilter.java:36)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:215)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2366)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
</snip>
These error messages were created with this Filter code
and I've added the check you suggested in your earlier
reply.
<snip>
package test;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public final class LanguageFilter implements Filter {
private FilterConfig filterConfig = null;
public void init(FilterConfig filterConfig) {
this.filterConfig = filterConfig;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain
chain) throws IOException, ServletException {
String servletPath = ((HttpServletRequest) request).getServletPath();
// If the first element is '/en/' or '/fr/' :
if (servletPath.indexOf("/en/") == 0 || servletPath.indexOf("/fr/") == 0) {
String lang = servletPath.substring(1,3);
request.setAttribute("lang", lang);
String targetURL = servletPath.substring(3);
System.out.println(targetURL);
RequestDispatcher rd = null;
ServletContext sc = this.filterConfig.getServletContext();
rd = sc.getRequestDispatcher(targetURL);
System.out.println("ok, RequestDispatcher created");
if (rd!=null) {
rd.forward(request, response);
}
return;
}
// No language match, so just handle the request as normal.
chain.doFilter(request, response);
}
public void destroy() {
}
}
</snip>
It works fine for URLs that do not start with /en/ or /fr/
so it really does seem to be a RequestDispatcher and not
Filter problem.
Stephen.
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