APPID = 'wx426b3015555a46be';
MCHID = '1900009851';
KEY = '8934e7d15453e97507ef794cf7b0519d';
APPSECRET = '7813490da6f1265e4901ffb80afaa36f';

<?php
require_once __DIR__ . '/BaseController.php';
require_once __DIR__ . '/../third_party/wxpay/WxPay.Api.php';

class WXPay extends BaseController {
  function index() {
  }
}

function index() {
//     初始化值对象
    $input = new WxPayUnifiedOrder();
//     文档提及的参数规范：商家名称-销售商品类目
    $input->SetBody("灵动商城-手机");
//     订单号应该是由小程序端传给服务端的，在用户下单时即生成，demo中取值是一个生成的时间戳
    $input->SetOut_trade_no('123123123');
//     费用应该是由小程序端传给服务端的，在用户下单时告知服务端应付金额，demo中取值是1，即1分钱
    $input->SetTotal_fee("1");
    $input->SetNotify_url("http://paysdk.weixin.qq.com/example/notify.php");
    $input->SetTrade_type("JSAPI");
//     由小程序端传给服务端
    $input->SetOpenid($this->input->post('openId'));
//     向微信统一下单，并返回order，它是一个array数组
    $order = WxPayApi::unifiedOrder($input);
//     json化返回给小程序端
    header("Content-Type: application/json");
    echo json_encode($order);
  }

$inputObj->SetNonce_str(self::getNonceStr());//随机字符串

 /**
   * 生成签名
   * @return 签名，本函数不覆盖sign成员变量，如要设置签名需要调用SetSign方法赋值
   */
  public function MakeSign()
  {
    //签名步骤一：按字典序排序参数
    ksort($this->values);
    $string = $this->ToUrlParams();
    //签名步骤二：在string后加入KEY
    $string = $string . "&key=".WxPayConfig::KEY;
    //签名步骤三：MD5加密
    $string = md5($string);
    //签名步骤四：所有字符转为大写
    $result = strtoupper($string);
    return $result;
  }

wx.login({
     success: function(res) {
      if (res.code) {
       //发起网络请求
       wx.request({
        url: 'https://api.weixin.qq.com/sns/jscode2session?appid=wx9114b997bd86f***&secret=d27551c7803cf16015e536b192******&js_code='+res.code+'&grant_type=authorization_code',
        data: {
         code: res.code
        },
        success: function (response) {
          console.log(response);
        }
       })
      } else {
       console.log('获取用户登录态失败！' + res.errMsg)
      }
     }
    });

    //统一下单接口对接
          wx.request({
            url: 'https://lendoo.leanapp.cn/index.php/WXPay',
            data: {
              openId: openId
            },
            success: function (response) {
              console.log(response);

            },
                header: {
            'content-type': 'application/x-www-form-urlencoded'
        },
          });

{
 "appid": "wx9114b997bd86f8ed",
 "mch_id": "1414142302",
 "nonce_str": "eEICgYFuGqxFRK6f",
 "prepay_id": "wx201701022235141fc713b8f80137935406",
 "result_code": "SUCCESS",
 "return_code": "SUCCESS",
 "return_msg": "OK",
 "sign": "63E60C8CD90394FB50E612D085F5362C",
 "trade_type": "JSAPI"
}

// 发起支付
var appId = response.data.appid;
var timeStamp = (Date.parse(new Date()) / 1000).toString();
var pkg = 'prepay_id=' + response.data.prepay_id;
var nonceStr = response.data.nonce_str;
var paySign = md5.hex_md5('appId='+appId+'&nonceStr='+nonceStr+'&package='+pkg+'&signType=MD5&timeStamp='+timeStamp+"&key=d27551c7803cf16***e536b192d5d03b").toUpperCase();
console.log(paySign);
console.log(appId);
wx.requestPayment({
  'timeStamp': timeStamp,
  'nonceStr': nonceStr,
  'package': pkg,
  'signType': 'MD5',
  'paySign': paySign,
  'success':function(res){
    console.log('success');
    console.log(res);
  }
});

errMsg:"requestPayment:fail"
err_code:2
err_desc:"支付验证签名失败"