关于poi导出excel三种方式HSSFWorkbook

  List<String> titles = (List<String>) model.get("titles");
  int len = titles.size();
  HSSFCellStyle headerStyle = workbook.createCellStyle(); //标题样式
  headerStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
  headerStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
  HSSFFont headerFont = workbook.createFont();   //标题字体
  headerFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
  headerFont.setFontHeightInPoints((short)11);
  headerStyle.setFont(headerFont);
  short width = 20,height=25*20;
  sheet.setDefaultColumnWidth(width);
  for(int i=0; i<len; i++){ //设置标题
     String title = titles.get(i);
     cell = getCell(sheet, 0, i);
     cell.setCellStyle(headerStyle);
     setText(cell,title);
  }
  sheet.getRow(0).setHeight(height);

  HSSFCellStyle contentStyle = workbook.createCellStyle(); //内容样式
  contentStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
  List<PageData> varList = (List<PageData>) model.get("varList");
  int varCount = varList.size();
  for(int i=0; i<varCount; i++){
     PageData vpd = varList.get(i);
     for(int j=0;j<len;j++){
        String varstr = vpd.getString("var"+(j+1)) != null ? vpd.getString("var"+(j+1)) : "";
        cell = getCell(sheet, i+1, j);
        cell.setCellStyle(contentStyle);
        setText(cell,varstr);
     }

  }
    varList.forEach(e ->{
        List<Object> ObjectList =  new ArrayList<>();
        for(int i=0;i<headers.length;i++){
            ObjectList.add(e.get("var"+(i+1))==null?null:e.getString("var"+(i+1)));
        }
       /* for (Object v : e.values()) {
            ObjectList.add(v);
        }*/
        Object[] objarr = new  Object[ObjectList.size()];
        for(int i = 0;i<ObjectList.size();i++){
            objarr[i] = ObjectList.get(i);
        }
        dataList.add(objarr);
    });
    ExportUtil exportUtil = new ExportUtil(sheetName,headers,dataList);
    //SXSSFWorkbook 大批量数据导出
    SXSSFWorkbook workBook =  exportUtil.export();
    // 如果文件名有中文，必须URL编码
    String  fileName1 = URLEncoder.encode(sheetName, "UTF-8");
    // response.reset();
    // response.setContentType("application/force-download");
    response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-Disposition", "attachment; filename=" + fileName1+".xls");
    workBook.write(outputStream);
    workBook.close();
    outputStream.flush();
    outputStream.close();

    //ObjectExcelView erv = new ObjectExcelView("逾期客户表");           //执行excel操作
    //mv = new ModelAndView(erv,dataMap);
} catch(Exception e){
    logger.error(e.toString(), e);
}
return new Object();