通过IO流的方式从WebApp里面下载文件

从WebApp里面下载Excel文件，文件路径：

• 1.Controller层代码:

/**
* 设备管理——导入模板下载
 *
 * @param requestType 下载标记
 * @return
 */
@RequestMapping(value = "/downLoadImportTemplate")
@ResponseBody
public ResponseResult downLoadImportTemplate(HttpServletRequest request,HttpServletResponse response, String requestType ) {
    ResponseResult result = new ResponseResult();
    try {
        if (StringUtils.isBlank(requestType)) {
            //获取文件路径
            String filepath = request.getServletContext().getRealPath("/downTemplate/downLoadImportTemplate.xlsx");
            //下载后的文件名
            String filename ="设备编号批量导入模板";
            ExportUtils.downLoadTemplateFromServer(filepath, response, filename);//下载
        }
    } catch (Exception e) {
        result.setResult(ResponseEnum.EXCEPTION);
        logger.error("设备编号批量导入模板下载 异常 ", e);
    }
    return result;
}

• 2.service层代码

 /**
    * 通过文件流的方式从服务器上下载文件模板
    *
    * @param filepath 文件模板的路径
    * @param filename 下载后的文件名
    */
   public static void downLoadTemplateFromServer(String filepath, HttpServletResponse response, String filename) throws Exception{
       byte[] content = FileUtils.readFileToByteArray(new File(filepath));
       response.setCharacterEncoding("gbk");
       String header = "attachment;filename=" + new String((filename).getBytes("UTF-8"), "ISO-8859-1");
       if(filepath.endsWith(".xlsx")){
           response.setHeader("Content-Disposition", header + ".xlsx");
           WebUtil.writeToResponse(response, content, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=gbk");
       }else{
           response.setHeader("Content-Disposition", header + ".xls");
           WebUtil.writeToResponse(response, content, "application/vnd.ms-excel;charset=gbk");
       }
   }

• 3.工具类WebUtil中，将流写进response

/**
* 将data写入http响应中
 * 
 * @param response
 * @param data
 * @param mimeType
 */
public static void writeToResponse(HttpServletResponse response, byte[] data, String mimeType) {
    response.setContentType(mimeType);
    ServletOutputStream outputStream = null;
    try {
        outputStream = response.getOutputStream();
        outputStream.write(data);
        outputStream.flush();
    } catch (IOException e) {
        logger.error("writeJsonToResponse error!", e);
        throw new RuntimeException(e);
    } finally {
        IOUtils.closeQuietly(outputStream);
    }
}