public static String parser(final String json, final String fieldName) {
        Map<String, Object> map = GsonUtils.getInstance().toObjectMap(json);
        String str = null;
        if (fieldName.contains(".")) {
            String[] split = fieldName.split("\\.");
            JsonObject jsonObject = (JsonObject) map.get(split[0]);
            for (int i = 1; i < split.length; i++) {
                if (i == split.length - 1) {
                    str = jsonObject.getAsJsonPrimitive(split[i]).getAsString();
                } else {
                    jsonObject = jsonObject.getAsJsonObject(split[i]);
                }
            }
        } else {
            return Objects.isNull(map.get(fieldName)) ? null : map.get(fieldName).toString();
        }
        return str;
    }
parser JSON.
@param json json Map
@param fieldName fieldName
@return str.
shenyu-plugin/shenyu-plugin-security/shenyu-plugin-cryptor/src/main/java/org/apache/shenyu/plugin/cryptor/utils/JsonUtil.java