// 登录
wx.login({
success: res => {
console.log("getUserremark:"+res.code);

wx.request({
url: 'http://localhost:7655/WebService.asmx/GetCode?json_code='+res.code,
data: {
'json_code': res.code
},
method: 'GET',
header: {
'content-type': 'appication/x-www-form-urlencoded'
},
success: function (res) {
console.log("back Data:"+res.data.data);
}
})
// 发送 res.code 到后台换取 openId, sessionKey, unionId
}
})

#region 获取小程序openid 和session_key
    [WebMethod]  //网页中显示这个方法
    public void GetCode(string json_code)
    {

        string serviceAddress =
            "https://api.weixin.qq.com/sns/jscode2session?appid=自己的&secret=自己的"
             + "&js_code=" + json_code + "&grant_type=authorization_code";
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(serviceAddress);
        request.Method = "GET";
        request.ContentType = "text/html;charset=utf-8";
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream myResponseStream = response.GetResponseStream();
        StreamReader myStreamReader = new StreamReader(myResponseStream, System.Text.Encoding.UTF8);
        string retString = myStreamReader.ReadToEnd();
        myStreamReader.Close();
        myResponseStream.Close();
        var obj = new
        {
            data = retString,
            Success = true
        };
        Formatting microsoftDataFormatSetting = default(Formatting);
        string result = JsonConvert.SerializeObject(obj, microsoftDataFormatSetting);
        HttpContext.Current.Response.Write(result);
    }
    #endregion