1.最近在项目中需要下载excel文件，直接下载打开会提示文件不可用或者文件已损害，利用poi可解决这个问题，步骤如下：

（1）通过httpServletRequest获取操作系统：

String osp = request.getHeader("User-Agent");
String os = "Linux";
if (osp.indexOf("Windows") != -1){
    os = "Windows";
}

（2）根据自己系统的查询方式得到文件路径

String path = staffTemplate.getSaveUrl() + staffTemplate.getServerName();

（3）设置下载文件名称，需要加excel后缀，其中sub根据系统文件名确定

if (os.equals("Windows")){
    name = new String(name.getBytes("UTF-8"),"ISO-8859-1");
           response.addHeader("Content-Disposition", "attachment; filename="+name+sub);
}else {
    response.addHeader("Content-Disposition", "attachment;                         filename=" + java.net.URLEncoder.encode(name, "UTF-8")+sub);
}

（4）利用poi实现excel的输出

//创建缓冲输入流
  BufferedInputStream bis = null;
  OutputStream outputStream = null;
  try {
       outputStream = response.getOutputStream();
       byte[] buff = new byte[1024];
       //这个路径为待下载文件的路径
       bis = new BufferedInputStream(new FileInputStream(new File(path)));
       Workbook workbook = null;
       //判断版本
       if (".xlsx".equals(sub)) {
            workbook = new XSSFWorkbook(bis);
        }else {
             workbook = new HSSFWorkbook(bis);
         }
        workbook.write(outputStream);
        outputStream.flush();
         } catch ( IOException e ) {
                    e.printStackTrace();
                    return error("网络错误，请重试！");
        } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (outputStream != null) {
                        try {
                            outputStream.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }