/// <summary>
    /// 上传多媒体文件,返回 MediaId
    /// </summary>
    /// <param name="ACCESS_TOKEN"></param>
    /// <param name="Type"></param>
    /// <returns></returns>
    public string UploadMultimedia(string ACCESS_TOKEN, string Type)
    {
        string result = "";
        string wxurl = "http://file.api.weixin.qq.com/cgi-bin/media/upload?access_token=" + ACCESS_TOKEN + "&type=" + Type;
        string filepath = Server.MapPath("image") + "\\hemeng80.jpg";(本地服务器的地址)
        WriteLog("上传路径:" + filepath);
        WebClient myWebClient = new WebClient();
        myWebClient.Credentials = CredentialCache.DefaultCredentials;
        try
        {
            byte[] responseArray = myWebClient.UploadFile(wxurl, "POST", filepath);
            result = System.Text.Encoding.Default.GetString(responseArray, 0, responseArray.Length);
            WriteLog("上传result:" + result);
            UploadMM _mode = JsonHelper.ParseFromJson<UploadMM>(result);
            result = _mode.media_id;
        }
        catch (Exception ex)
        {
            result = "Error:" + ex.Message;
        }
        WriteLog("上传MediaId:" + result);
        return result;
    }