<input type="file" lay-type="file" id="xxxxx" name="file" class="layui-upload-file">

layui.upload({
  url: '/pay_channel/upload'
  ,before: function(input){
   //返回的参数item，即为当前的input DOM对象
   $(input).after('<input type="hidden" name="mchId-file" value="11111"/>');
   //layer.msg('文件上传中',{zIndex:20180509});
  }
  ,success: function(res){
  if(res.code == 'success'){
   layer.msg(res.message,{zIndex:20180510});
   certLocalPath = res.filePath
  }else{
   layer.msg(res.message,{zIndex:20180510});
  }
  }

});

  @RequestMapping("/upload")
  @ResponseBody
  public String importFile(MultipartFile file, HttpServletRequest request) {
   JSONObject object = new JSONObject();
      try {
       String mchId = request.getParameter("mchId-file");
       String originalFilename = file.getOriginalFilename();
//       String dirPath = System.getProperty("user.dir")+"/wx";
//       String dirPath = this.getClass().getClassLoader().getResource("").getPath()+"wx";
       String dirPath = "/xxxx/java/pay/wx/cert";
       _log.info("证书上传的文件目录{}", dirPath);
       String filePath = "/"+mchId+"_"+originalFilename;
  boolean b = new File(dirPath).mkdirs();
  file.transferTo(new File(dirPath + filePath).getAbsoluteFile());
  
  object.put("filePath", filePath);
  object.put("code", "success");
  object.put("message", "文件上传成功");
  } catch (IOException e) {
  e.printStackTrace();
  object.put("code", "fail");
  object.put("message", "文件上传失败");
  }
      return object.toJSONString();

  }