以流的方式下载文件

 public static HttpServletResponse downloadStream(HttpServletResponse response, String filePath) throws AdminException {
        response.setContentType("text/html;charset=UTF-8");
        try {
            // path是指欲下载的文件的路径
            File file = new File(filePath);
            // 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(filePath));
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();
            // 清空response
            response.reset();
            // 设置response的Header
            response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes("UTF8"), "ISO8859-1"));
            response.addHeader("Content-Length", "" + file.length());
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            toClient.write(buffer);
            toClient.flush();
            toClient.close();
        } catch (IOException ex) {
           logger.error("下载失败”，e);
        }
        return response;
    }