java - Unable to access session data in servlet filter on app engine dev server -

i trying write session filter centralize authorization check in app engine web app.

my filter looks :

@override public void dofilter(servletrequest request, servletresponse response,         filterchain chain) throws ioexception, servletexception {     httpservletrequest httpreq = (httpservletrequest) request;     httpservletresponse httpresp = (httpservletresponse) request;     httpsession session = httpreq.getsession();      httpreq.setcharacterencoding("utf-8");     httpresp.setcharacterencoding("utf-8");     httpresp.setcontenttype("application/json");      boolean isauthorized = (boolean) session.getattribute("isauthorized");      if (!isauthorized || isauthorized == null) {         httpresp.senderror(httpservletresponse.sc_unauthorized);     } else {         chain.dofilter(request, response);     } } 

but when i'm launching app engine dev server i'm greeted exception : "org.mortbay.jetty.request cannot cast javax.servlet.http.httpservletresponse". doing wrong?

you trying cast "request" object response.

change follows

httpservletresponse httpresp = (httpservletresponse) response;