微信小程序外部API调用方法，遇到的一个小问题

最近对微信小程序比较感兴趣，想写一个查询车辆违章记录的小程序。在调用外部接口时需要，appcode 这种authoriztion。发现微信小程序的

ajax请求使用这种方式不起作用。改为直接在header中赋值生效了，不知道什么原因，希望遇到同样问题的伙伴可以不用弯路。

 beforeSend: function (xhr){
        console.log('授权码');
        xhr.setRequestHeader("Authorization", "APPCODE "+"XXXXXXXXXXXXXXXXXXX");
      },

解决方法

 header: {
        'content-type': 'application/json',
        'Authorization': "APPCODE " + "XXXXXXXXXXXXXXXXXXX"
      },

详细代码如下

confirm: function () {
    console.log("clicked confirm");
    this.setData({
      hidden: true
    });

    var timestamp = new Date().getTime();

    var apiUrl = "http://ddycapi.market.alicloudapi.com/violation/query";

    //注释掉的代码为废弃车首页和路帮网的免费接口，使用阿里云的api收费服务
    //var appId = "129";
    //var appKey = "4263c4f0-4f56-0135-3375-0242c0a80006";
    //var carInfo = "{plate_num=" + this.data.plateNo + "&body_num=" + this.data.frameNo + "&engine_num=" + this.data.engineNo + "&city_id=190&car_type=02}";
   // var signStr = appId + carInfo + timestamp + appKey;
   // var sign = util.md5(signStr);
    //console.log("carInfo:" + carInfo);
    //console.log("signStr:" + signStr);
    //console.log("sign:" + sign);
    //var url = apiUrl + "car_info=" + carInfo + "&api_id=" + appId + "&sign=" + sign + "×tamp=" + timestamp;
   // console.log("url:" + url);

    var that = this;
    wx.request({
      url: apiUrl,
      method:'post',
      data: { "plateNumber": "陕AD3738", "engineNo": "695176712", "vin": "662722", "carType": "02" },
      header: {
        'content-type': 'application/json',
        'Authorization': "APPCODE " + "XXXXXXXXXXXXXXXXXXX"
      },
      beforeSend: function (xhr){
        console.log('授权码');
        xhr.setRequestHeader("Authorization", "APPCODE "+"XXXXXXXXXXXXXXXXXXX");
      },
      success: function (res) {
        if (res.statusCode != 200) {
          console.log('接口调用异常');
          that.setData({
            resultModalHidden: false,
            resultMsg: '接口调用异常'
          });
        }
        var obj = res.data;
        var status = Number(obj.status);
        that.setData({
          resultModalHidden: false
        });
        switch (status) {

          case 1002:
            console.log('app_id有误');
            break;
          case 1003:
            console.log('	sign加密有误');
            break;
          case 1004:
            console.log('车牌号，汽车类型，违章城市 等字段不能为空');
            break;
          case 1005:
            that.setData({
              resultMsg: '输入的车辆信息有误，请查证后重新输入'
            });
            console.log('车辆信息有误');
            break;
          case 2000:
            that.setData({
              resultMsg: '恭喜，当前城市交管局暂无您的违章记录'
            });
            console.log('正常(无违章记录)');
            break;
          case 2001:
            console.log('正常（有违章记录）');
            break;
          case 5000:
            console.log('请求超时，请稍后重试');
            break;
          case 5001:
            console.log('交管局系统连线忙碌中，请稍后再试');
            break;
          case 5002:
            console.log('恭喜，当前城市交管局暂无您的违章记录');
            break;
          case 5003:
            console.log('数据异常，请重新查询');
            break;
          case 5004:
            console.log('系统错误，请稍后重试');
            break;
          case 5005:
            console.log('	车辆查询数量超过限制');
            break;
          case 5006:
            console.log('你访问的速度过快, 请后再试');
            break;
          case 5008:
            that.setData({
              resultMsg: '输入的车辆信息有误，请查证后重新输入'
            });
            console.log('输入的车辆信息有误，请查证后重新输入');
            break;
          default:
            console.log('未知错误');
        }

        console.log(res)
      }
    })

  },