javaWeb 实现文件下载的功能

@RequestMapping(value = "/downloadQrcode",method = RequestMethod.GET)
@ResponseBody
public void download(HttpServletRequest request,HttpServletResponse response){
String Qfile = request.getParameter("Qfile");
try{
QRCodeUtil.fileDownLoad(request,response, Qfile);
}catch (IOException e) {
e.printStackTrace();
Log.error(TAG, e.toString());
}
}

public static void fileDownLoad(HttpServletRequest request, HttpServletResponse response, String srcname) throws IOException{
OutputStream os = null;
try {
os = new BufferedOutputStream(response.getOutputStream());
response.reset();
response.setHeader("Content-Disposition", "attachment; filename="+srcname);
response.setContentType("application/octet-stream; charset=utf-8");
String filename = FileConstants.getLocalDir() +"/"+ srcname;//FileConstants.getLocalDir()为服务器上文件的全路径
if(!f.exists()){
//文件不存在
return;
}
os.write(FileUtils.readFileToByteArray(f));
os.flush();
}
finally {
if (os != null) {
os.close();
}
}
}