spring mvc 文件下载怎么不成功呢？

在firebug下面我可以看到后台的2.9M的数据已经传到了前台，可是就是没有显示保存文件那样的对话框出来，真心不知道怎么回事了。。。。

下面是我网前台返回数据流的代码，希望大家能够帮个忙看看究竟怎么回事。。。

  @RequestMapping("downLoadSelect")
    public void downloadSelect(int[] ids, HttpServletResponse response, HttpServletRequest request){
        
            File zipFile = null;
            try {
                zipFile = tupianxxService.downLoad(request,response, ids);
            } catch (Exception e1) {
                e1.printStackTrace();
            }
            response.reset();
            response.setCharacterEncoding("utf-8");
            response.setContentType("APPLICATION/OCTET-STREAM"); 
            response.setHeader("Content-Disposition", "attachment;fileName=abc.zip");
            try {
                InputStream ins=new FileInputStream(zipFile);
                OutputStream bout = new BufferedOutputStream(response.getOutputStream());
                byte[] b=new byte[1024];
                int length;
                while((length=ins.read(b))>0){
                    bout.write(b,0,length);
                }
                bout.flush();
                bout.close();
                ins.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
    }