struts1 文件下载

//实现文件下载public ActionForward downLoad(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception { String fname  = request.getParameter("fname") ; String path = request.getSession().getServletContext().getRealPath("/upload")+"/"+fname; InputStream is  = new FileInputStream(new File(path)) ; OutputStream os  = response.getOutputStream() ; response.setHeader("Content-disposition", "attachment;filename="+URLEncoder.encode(path,"utf-8")); int len = 0 ; byte[] b = new byte[1024] ;  while((len=is.read(b))!=-1){ os.write(b,0,len) ; }  os.flush() ; os.close() ; is.close() ;  System.out.println("下载完毕 "); return null;}