问题：android调用sendReq返回false，无法启动微信支付

1. 应用包名与开放平台一致

2. appid与开放平台一致
   

3. 签名已检验，和生成工具一致，且小写去了分号

4. 后台返回的sign用检验工具检测也是正确的

req.sign = weixinreq.sign;
req.timeStamp = weixinreq.timeStamp;
req.nonceStr = weixinreq.nonceStr;
req.prepayId = weixinreq.prepayId;
req.packageValue = weixinreq.packageValue;
req.appId = Constant.WEIXIN_APP_ID;
req.partnerId = weixinreq.partnerId;
boolean b = api.sendReq(req);