code: public UploadMaterialResponse uploadMaterialNews(List<Article> articles){
          UploadMaterialResponse response;
          String url = BASE_API_URL + "cgi-bin/material/add_news?access_token=#";
          final Map<String, Object> params = new HashMap<String, Object>();
          params.put("articles", articles);
          BaseResponse r = executePost(url, JSONUtil.toJson(params));
          String resultJson = isSuccess(r.getErrcode()) ? r.getErrmsg() : r.toJsonString();
          response = JSONUtil.toBean(resultJson, UploadMaterialResponse.class);
          return response;
      }
docs: 上传图文消息素材
  @param articles 图文消息列表
  @return 上传结果