dispatcher.error(request, response);
if(dispatcher!=null) dispatcher.error(request, response); else throw new HttpException(500,"No dispatcher for "+error_page);
        public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch) throws IOException        {            if (_errorPages!=null)            {                String error_page= null;                Class exClass= (Class)request.getAttribute(ServletHandler.__J_S_ERROR_EXCEPTION_TYPE);                                if (ServletException.class.equals(exClass))                {                    error_page= (String)_errorPages.get(exClass.getName());                    if (error_page == null)                    {                        Throwable th= (Throwable)request.getAttribute(ServletHandler.__J_S_ERROR_EXCEPTION);                        while (th instanceof ServletException)                            th= ((ServletException)th).getRootCause();                        if (th != null)                            exClass= th.getClass();                    }                }                                while (error_page == null && exClass != null )                {                    error_page= (String)_errorPages.get(exClass.getName());                    exClass= exClass.getSuperclass();                }                                if (error_page == null)                {                    Integer code=(Integer)request.getAttribute(ServletHandler.__J_S_ERROR_STATUS_CODE);                    if (code!=null)                        error_page= (String)_errorPages.get(TypeUtil.toString(code.intValue()));                }                                if (error_page!=null)                {                    String old_error_page=(String)request.getAttribute(ERROR_PAGE);                    if (old_error_page==null || !old_error_page.equals(error_page))                    {                        request.setAttribute(ERROR_PAGE, error_page);                        Dispatcher dispatcher = (Dispatcher) getServletHandler().getServletContext().getRequestDispatcher(error_page);                        try                        {                            dispatcher.error(request, response);                        }                        catch (ServletException e)                        {                            Log.warn(Log.EXCEPTION, e);                        }                        return;                    }                }            }                        super.handle(target, request, response, dispatch);        }