坑一：调用支付jsapi缺少参数 total_fee

修正后的uniapp代码如下：

uni.requestPayment({provider: 'wxpay',timeStamp: String(data.timestamp),nonceStr: data.nonceStr,package: 'prepay_id=' + data.prepayId,signType: 'HMAC-SHA256',paySign: data.sign,success: (res) => {console.log('success:' + JSON.stringify(res));uni.showToast({title: '支付成功！',duration: 2000});uni.reLaunch({url: '/pages/order/list'})},fail: (err) => {console.log('fail:' + JSON.stringify(err));uni.showToast({title: '已取消支付！',icon: 'none',duration: 2000});}});

解决方案：

其中package: ‘prepay_id=’ + data.prepayId,这一行代码，必须拼接‘prepay_id=’

坑二：小程序支付报错：支付签名验证失败

修正后的后台代码：

    /*** 按照前端签名文档规范进行排序，\n是换行** @param appid* @param timestamp* @param nonceStr* @param prepay_id* @return*/public static String buildMessage(String appid, long timestamp, String nonceStr, String prepay_id) {return appid + "\n"+ timestamp + "\n"+ nonceStr + "\n"+ "prepay_id=" + prepay_id + "\n";}

文档官方文档：
https://pay.weixin.qq.com/docs/merchant/apis/jsapi-payment/jsapi-transfer-payment.html

$ echo -n -e \
"wx8888888888888888\n1414561699\n5K8264ILTKCH16CQ2502SI8ZNMTM67VS\nprepay_id=wx201410272009395522657a690389285100\n" \| openssl dgst -sha256 -sign apiclient_key.pem \| openssl base64 -AuOVRnA4qG/MNnYzdQxJanN+zU+lTgIcnU9BxGw5dKjK+VdEUz2FeIoC+D5sB/LN+nGzX3hfZg6r5wT1pl2ZobmIc6p0ldN7J6yDgUzbX8Uk3sD4a4eZVPTBvqNDoUqcYMlZ9uuDdCvNv4TM3c1WzsXUrExwVkI1XO5jCNbgDJ25nkT/c1gIFvqoogl7MdSFGc4W4xZsqCItnqbypR3RuGIlR9h9vlRsy7zJR9PBI83X8alLDIfR1ukt1P7tMnmogZ0cuDY8cZsd8ZlCgLadmvej58SLsIkVxFJ8XyUgx9FmutKSYTmYtWBZ0+tNvfGmbXU7cob8H/4nLBiCwIUFluw==

解决方案：

注意看，后台生成sign时候，拼接的字符串中，也需要加上"prepay_id="

tips：

app支付和小程序支付的代码之前还有这种差别和坑…腾讯的开发文档真是抵不上阿里文档的一个脚趾头…