方法一：

@RequestMapping('download')def download(HttpServletRequest request, HttpServletResponse response) {    TtxSession session = getSession(request)    String fileName='OrderData--20190225.csv'    String pathName="C:\\export\\OrderData--20190225.csv"    downloadFile(response, fileName) { HttpServletResponse res ->        byte[] bs = new File(pathName).toPath().readBytes()        response.getOutputStream().write(bs)    }    return null}方法二

@RequestMapping('downloads')def downloads(HttpServletRequest request, HttpServletResponse response) {    String path="C:\\export\\OrderData--20190225.csv"    // path是指欲下载的文件的路径。    File file = new File(path)    // 取得文件名。    String filename = file.getName()    // 取得文件的后缀名。    String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase()    // 以流的形式下载文件。    InputStream fis = new BufferedInputStream(new FileInputStream(path))    byte[] buffer = new byte[fis.available()]    fis.read(buffer)    fis.close()    // 清空respons    response.reset()    // 设置response的Header    response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()))    response.addHeader("Content-Length", "" + file.length())    OutputStream toClient = new BufferedOutputStream(response.getOutputStream())    response.setContentType("application/octet-stream")    toClient.write(buffer)    toClient.flush()    toClient.close()    return null}