@Override
    public ResponseInfo sendToGroup(String groupId, MessageType messageType, String message) {
        //验证
        if (StringUtils.isEmpty(groupId)) {
            throw new IllegalArgumentException("群发消息时，没有指定组的ID!");
        }
        if (StringUtils.isEmpty(message)) {
            throw new IllegalArgumentException("群发消息时，没有指定消息的内容!");
        }
        if (messageType == null) {
            throw new IllegalArgumentException("群发消息时，没有指定消息类型!");
        }
        //组装消息
        JsonObject jsonObject = new JsonObject();
        jsonObject.add(GROUP, GsonHelper.addElement("group_id", "2"));

        if (MessageType.NEWS.equals(messageType)) {//图文消息
            jsonObject.add("mpnews", GsonHelper.addElement("media_id", message));
            jsonObject.addProperty(MESSAGE_TYPE, "mpnews");
        } else if (MessageType.TEXT.equals(messageType)) {//文本消息
            jsonObject.add("text", GsonHelper.addElement("content", message));
            jsonObject.addProperty(MESSAGE_TYPE, "text");
        } else if (MessageType.VOICE.equals(messageType)) {//语音消息
            jsonObject.add("voice", GsonHelper.addElement("media_id", message));
            jsonObject.addProperty(MESSAGE_TYPE, "voice");
        } else if (MessageType.VIDEO.equals(messageType)) {//视频消息
            jsonObject.add("mpvideo", GsonHelper.addElement("media_id", message));
            jsonObject.addProperty(MESSAGE_TYPE, "mpvideo");
        } else if (MessageType.IMAGE.equals(messageType)) {//图片消息
            jsonObject.add("image", GsonHelper.addElement("media_id", message));
            jsonObject.addProperty(MESSAGE_TYPE, "image");
        }
        //获得要发送的数据
        Gson gson = new Gson();
        String json = gson.toJson(jsonObject);
        String url = RequestWrapper.getUrl(WeChatUrl.SEND_TO_GROUP);
        StringEntity entity = null;
        try {
            entity = new StringEntity(json, "application/json", "utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        //发送
        String result = SimpleRequest.doPost(url, entity);
        return RequestWrapper.getResponseInfo(result);
    }