code: public DownloadMaterialResponse getMaterial(String mediaId) {
  		DownloadMaterialResponse materialresponse = null;
          String url = BASE_API_URL + "cgi-bin/material/get_material?access_token=#";
          Map<String, String> param = new HashMap<String, String>();
          param.put("media_id", mediaId);
          BaseResponse r = executePost(url, JSONUtil.toJson(param));
          String resultJson = isSuccess(r.getErrcode()) ? r.getErrmsg() : r.toJsonString();
          materialresponse = JSONUtil.toBean(resultJson, DownloadMaterialResponse.class);
          return materialresponse;
  	}
docs: 获得永久素材的信息、只获取信息、不进行下载
  @param mediaId
  @return