获取微信企业号media_id

protected void Button1_Click(object sender, EventArgs e)
        {
            if (File1.PostedFile.ContentLength != 0)
            {
                //获取 ACCESS_TOKEN
                string accessjson = pub.Weixin.GetAccessToken();
                M.accessstring access_model = pub.json.JsonDeserializeBySingleData(accessjson);
                string ACCESS_TOKEN = access_model.access_token;                //获取ACCESS_TOKEN
                string type = "image";
                //发送请求url
                string sUrl = "https://qyapi.weixin.qq.com/cgi-bin/material/add_material?type="+ type + "&access_token=" + ACCESS_TOKEN;

                if (File1.PostedFile.ContentLength!=0)
                {
                    string filename = File1.PostedFile.FileName;
                    string path = Server.MapPath("./");
                    path += filename;

                    if (File.Exists(path)) {
                        Response.Write("文件已经存在");
                        return;
                    }
                    File1.PostedFile.SaveAs(path);

                    WebClient myWebClient = new WebClient();
                    myWebClient.Credentials = CredentialCache.DefaultCredentials;
                    try {
                        //上传数据获得字符
                        byte[] responseArray = myWebClient.UploadFile(sUrl,"POST",path);
                        //转换字符
                        string ret = System.Text.Encoding.Default.GetString(responseArray,0,responseArray.Length);
                        //解析json
                        M.material mymaterial = pub.json.JsonDeserializeBySingleData(ret);
                        Response.Write(mymaterial.media_id);
                    }
                    catch(Exception ex) {
                    }
                }
            }
        }

参考网址：

http://bbs.csdn.net/topics/391014694/