how to implement a front controller?

hello

I wanted to write a simple front controller. As for now it is to do nothing else than just take a look inside a request, check what page a client wants to see and just forward a request to an appropriate page. Is it possible? 
In my web.xml I put mapping for all requests to be checked by my front controller:
<servlet>
    <servlet-name>FrontController</servlet-name>
    <servlet-class>frontController</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>FrontController</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

in doProcess:

String urlTarget = request.getgetPathInfo();
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(urlTarget);
dispatcher.forward( request, response );

when I try to visit any page in my webapp I get the error
java.lang.ClassCastException
        at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:243)
        .....                at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2344)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
        at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
        at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
        at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
        at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:462)
                ....Do you have any idea of what is wrong with my piece of code?thanks in advance