Excessão em response.getOutputStream() ao exportar relatório para XLS

OutputStream ouputStream = response.getOutputStream();

public ActionForward executeAction(ActionMapping mapping,
            ActionForm form, HttpServletRequest request,
            HttpServletResponse response)
            throws Exception {

    	//OutputStream ouputStream = response.getOutputStream();

    	ActionForward forward = new ActionForward(FORWARD_ERRO);
    	
        StreamInfo info = getReport(mapping, form, request, response, forward);
        
        // Caso não se consiga gerar o Relatorio, chamar pagina de Erro
        if (info == null) {
            return forward;
        }

        // Caso possa gerar o relatorio, seta-lo no response

        String contentType = info.getContentType();
        InputStream stream = info.getInputStream();

        response.setContentType(contentType);
        PrintWriter writer = response.getWriter();
        CopiadorDados.copiar(stream, writer);

        ActionMessages m = new ActionMessages();
        m.add(ActionMessages.GLOBAL_MESSAGE, new ActionMessage(
                "mensagem.sucesso.geracao_relatorio"));
        addMessages(request, m);
        return mapping.findForward(FORWARD_SUCESSO);
    }

    /**
     * Retorna um StreamInfo com as informacoes do relatorio.
     * @param mapping Mapping
     * @param form Formulario da requisicao
     * @param request Request
     * @param response Response
     * @param forward Pagina de redirecionamento no caso do retorno ser null.
     * @return Retorna null caso houver algum erro na geracao do relatório, do
     * contrário, retorna um StreamInfo com as informacoes do relatorio
     * @throws Exception
     */
    protected StreamInfo getReport(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response,
            ActionForward forward)
            throws Exception {

        String tituloRelatorio = request.getParameter("tituloRelatorio");
        String tipoRelat = request.getParameter("tipoRelatorio");
        UsuarioVO usuarioVO = ControleAcesso.getUsuarioLogado(request);
        SASConnectionManager sasConnectionManager = new SASConnectionManager(usuarioVO);
        Connection connection = sasConnectionManager.getConnection();
        int tipoRelatorio = JasperReportFactory.TIPO_HTML; 

        HashMap parametros = new HashMap();
        parametros.put("libname", sasConnectionManager.getNomeLib());
        parametros.put("dataset", getDatasetName(tituloRelatorio));
        parametros.put("cenario", request.getSession().getAttribute(Constantes.CHAVE_CENARIO_SELECIONADO));
        Enumeration parameterNames = request.getParameterNames();
        while (parameterNames.hasMoreElements()) {
            String key = (String) parameterNames.nextElement();
            parametros.put(key, request.getParameter(key));
        }
        
        /* passagem de parametro para integracao do Grafico de Backlog */
        
        Object o = request.getSession().getAttribute("grafico_backlog");
        
        if (o != null ) {
            Image imagem = (Image)o;
            parametros.put("grafico_backlog", imagem);
        }
        
        JasperReportFactory jasperReportFactory = new JasperReportFactory();

        if (tituloRelatorio == null)
            return null;
        
        if(tipoRelat!=null && !tipoRelat.trim().equals("")){
        	try{
        		tipoRelatorio = Integer.parseInt(tipoRelat);
        	} catch(Exception e){
        		e.printStackTrace();
        	}
        }
        
        return jasperReportFactory.fabrica(
            tituloRelatorio, parametros, tipoRelatorio,
            connection, response);

    }

public StreamInfo fabrica(String tituloRelatorio, HashMap parametros,
            int tipo, Connection fonteDados, HttpServletResponse response) throws JRException, IOException{
        String sep = System.getProperty("file.separator");
        InputStream inputStream =
            RelatorioFactory.class.getResourceAsStream("/"
                + tituloRelatorio + ".jasper");

        if (inputStream == null) {
            throw new IOException("Relatório Jasper não foi compilado.");
        }
        
        JasperPrint print = null;
        try {
            print = JasperFillManager.fillReport(
                    inputStream, parametros, fonteDados);
        } catch (JRException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        switch (tipo) {
        case TIPO_PDF:
            return new ByteArrayStreamInfo("application/pdf",
                        JasperExportManager.exportReportToPdf(print));
            
        case TIPO_XLS:

        	JRXlsExporter exporter = new JRXlsExporter();   
        	ByteArrayOutputStream xlsReport = new ByteArrayOutputStream();   
        	exporter.setParameter(JExcelApiExporterParameter.JASPER_PRINT, print);   
        	exporter.setParameter(JExcelApiExporterParameter.OUTPUT_STREAM, xlsReport);   
        	exporter.setParameter(JExcelApiExporterParameter.IS_REMOVE_EMPTY_SPACE_BETWEEN_ROWS, Boolean.TRUE);   
        	exporter.setParameter(JExcelApiExporterParameter.IS_WHITE_PAGE_BACKGROUND, Boolean.TRUE);   
        	exporter.setParameter(JExcelApiExporterParameter.IS_ONE_PAGE_PER_SHEET, Boolean.TRUE);   
        	   
        	exporter.exportReport();   
        	byte[] bytes = xlsReport.toByteArray();   
        	response.setContentType("application/vnd.ms-excel");   
        	response.setContentLength(bytes.length);   
        	xlsReport.close();
        	OutputStream ouputStream = response.getOutputStream();   
        	ouputStream.write(bytes, 0, bytes.length);   
        	ouputStream.flush();   
        	ouputStream.close();
            
            return new ByteArrayStreamInfo("application/vnd.ms-excel", bytes);
            
        case TIPO_HTML:
            JRHtmlExporter exportador = new JRHtmlExporter();
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            exportador.setParameter(JRExporterParameter.JASPER_PRINT, print);
            exportador.setParameter(JRExporterParameter.OUTPUT_STREAM, stream);
            exportador.setParameter(
                JRHtmlExporterParameter.IS_USING_IMAGES_TO_ALIGN,
                Boolean.FALSE);
            exportador.setParameter(
                JRHtmlExporterParameter.IS_OUTPUT_IMAGES_TO_DIR, Boolean.TRUE);
            String tempDirName = "jrimg" + Math.random() + "tmp";
            File tempDir = new File(System.getProperty("java.io.tmpdir")
                + sep
                + tempDirName); 
            tempDir.mkdir();
            tempDir.deleteOnExit();
            exportador.setParameter(
                JRHtmlExporterParameter.IMAGES_DIR,
                tempDir
                );
            exportador.setParameter(JRHtmlExporterParameter.IMAGES_URI,
                "exibirImagemTemporaria.do?caminho=" + tempDirName + sep);
            
            /* Action do Jasper para exportar imagens 
             * utilizado pelo Murer para imagens*/
//            exportador.setParameter(JRHtmlExporterParameter.IMAGES_URI,
//                new StringBuffer("htmlJasperImagerAction?").append(
//                    ImageServlet.JASPER_PRINT_REQUEST_PARAMETER)
//                    
//      .append("=jasperPrint_image&image=").toString());
//
//            request.getSession().setAttribute(
//                "jasperPrint_image",
//                print);

            
            exportador.exportReport();
         
            return new ByteArrayStreamInfo("text/html",
                stream.toByteArray());
        }
        return null;
    }