java 文件下载

//下载任务
 public String synchronyTask()throws Exception{
  HttpServletResponse response = super.getHttpResponse();
  try {   
   response.setContentType("text/html;charset=UTF-8");
   byte output[];
   JSONObject branchObject=offRegionService.synchronyTask();
   response.setContentType("application/octet-stream");  
            response.setCharacterEncoding("UTF-8");           
         response.setHeader("Content-Disposition", "inline; filename=\""  
                    + URLEncoder.encode("data", "UTF-8") + ".json\"");  
            output = branchObject.toString().getBytes();
   HttpServletResponse res = response;
   OutputStream os = res.getOutputStream();
   os.write(output);   
   os.close();   
  } catch(Exception e) {
   e.printStackTrace();
  } 
  return null;
 }