StringBuilder sb = new StringBuilder();
sb.append(prepayInfo.getAppid()).append(BaseConsts.LF).append(prepayInfo.getTimestamp()).append(BaseConsts.LF).append(prepayInfo.getNoncestr()).append(BaseConsts.LF).append(prepayInfo.getPrepayid()).append(BaseConsts.LF);
https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=4_3