java – 设置byte []作为文件下载

代码的相关部分如下所示,这是从AJAX请求启动的(页面已经加载)：

JasperReport jasperReport;
    JasperPrint jasperPrint;
    HttpServletResponse response = (HttpServletResponse) context.getExternalContext().getResponse();    

    byte[] excel = null;
    FacesContext facesContext = FacesContext.getCurrentInstance();

    try {
        ArrayList<SwimDataReport> dataList = getData();
        if(dataList!=null){
            JRBeanCollectionDataSource dataSource = new JRBeanCollectionDataSource(dataList,false);

            jasperReport = JasperCompileManager.compileReport(reportFile.getPath());
            jasperPrint = JasperFillManager.fillReport(jasperReport,parameters,dataSource);
            JRXlsExporter exporter = new JRXlsExporter();
            ByteArrayOutputStream  xlsReport = new ByteArrayOutputStream();
            exporter.setParameter(JRExporterParameter.JASPER_PRINT,jasperPrint);
            exporter.setParameter(JRExporterParameter.OUTPUT_STREAM,xlsReport);            
            exporter.exportReport();
            excel = xlsReport.toByteArray();

            response.reset();
            response.setContentType("application/vnd.ms-excel");
            response.setHeader("Content-disposition","attachment; filename="Export.xls"");

            xlsReport.close();

            OutputStream  ouputStream = response.getOutputStream();
            ouputStream.write(excel);
            ouputStream.close();

            facesContext.responseComplete();
            this.cleanUp();
        }else{
            return;
        }
    } catch (JRException e) {       
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }

我出错的任何想法？