protected long readLongValue() {
            int beginIndex = pos - 1;
            if (ch == '+' || ch == '-') {
                next();
            }

            while (ch >= '0' && ch <= '9') {
                next();
            }

            int endIndex = pos - 1;
            String text = path.substring(beginIndex, endIndex);
            long value = Long.parseLong(text);
            return value;
        }
@since 1.2.51
@param json
@param path
@return
src/main/java/com/alibaba/fastjson/JSONPath.java