java Web頁面實現下載

在網上搜索到下載方法，總是有一些問題，浪費了一些時間.

1.response.reset();//清除首部的空白行

沒加這個導致文件莫名其妙的多出0.01 KB之類，像音頻文件直接導致不能使用

    /**
     * 網頁文件下載
     * @param response
     * @param fileName 文件名
     * @param contents
     */
    public  void downloadFile(HttpServletResponse response, String fileName, byte[] contents) {
        if (fileName != null && contents.length !=0) {
            response.reset();//清除首部的空白行
            response.setHeader("content-type", "application/octet-stream");
            response.setContentType("application/octet-stream");
            try {
                response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(fileName, "UTF-8"));
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
                writeLog("downloadFile_response_set:"+e);
            }
            byte[] buffer = new byte[1024];
            BufferedInputStream bis = null;
            try {
                bis = new BufferedInputStream(new ByteArrayInputStream(contents));
                OutputStream os = response.getOutputStream();
                int i ;
                while ((i= bis.read(buffer)) != -1) {
                    os.write(buffer, 0, i);
                }
                os.flush();
            } catch (Exception e) {
                e.printStackTrace();

            } finally {
                if (bis != null) {
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();

                    }
                }
            }
        }
    }