var time = ‘@ViewBag.Share.timestamp‘;
      wx.config({
        debug: false, // 开启调试模式,调用的所有api的返回值会在客户端alert出来，若要查看传入的参数，可以在pc端打开，参数信息会通过log打出，仅在pc端时才会打印。
        appId: ‘@ViewBag.Share.appId‘, // 必填，公众号的唯一标识
        timestamp: parseInt(time), // 必填，生成签名的时间戳
        nonceStr: ‘@ViewBag.Share.nonceStr‘, // 必填，生成签名的随机串
        signature: ‘@ViewBag.Share.signature‘,// 必填，签名，见附录1
          jsApiList: ["chooseImage", "previewImage", "uploadImage", "downloadImage"] // 必填，需要使用的JS接口列表，所有JS接口列表见附录2
      });
        wx.ready(function() {
            $(document).on("click", ".ctcon", function() {
                wx.chooseImage({
                    count: 1, // 默认9
                    sizeType: [‘original‘, ‘compressed‘], // 可以指定是原图还是压缩图，默认二者都有
                    sourceType: [‘album‘, ‘camera‘], // 可以指定来源是相册还是相机，默认二者都有
                    success: function (res) {
                        var localIds = res.localIds; // 返回选定照片的本地ID列表，localId可以作为img标签的src属性显示图片
                        uploadimg(localIds[0].toString());

                    }
                });
            });

　　　　　　　　　　　　　　　　
function uploadimg(lid) {
                wx.uploadImage({
                    localId: lid, // 需要上传的图片的本地ID，由chooseImage接口获得
                    isShowProgressTips: 1, // 默认为1，显示进度提示
                    success: function (res) {
                        var serverId = res.serverId; // 返回图片的服务器端ID
                        //alert(serverId);
                        $.post("/Question/DownWxImage", { serverId: serverId }, function(res) {
                            //alert(res.SaveName);
                            if (res.Success === true) {
                                 // 显示图片
                            }
                           
                        });
                });
            }

        });

  public ActionResult DownWxImage(string serverId)
        {
            var token = getToken();
             var url = string.Format("http://file.api.weixin.qq.com/cgi-bin/media/get?access_token={0}&media_id={1}",
                 token, serverId);//图片下载地址

             HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);

             req.Method = "GET";
             using (WebResponse wr = req.GetResponse())
             {
                 HttpWebResponse myResponse = (HttpWebResponse)req.GetResponse();

                var strpath = myResponse.ResponseUri.ToString();
                 WebClient mywebclient = new WebClient();

                 var path = "/Content/UploadFiles/mobile/";
                 var uploadpath = Server.MapPath(path);
                 if (!Directory.Exists(uploadpath))
                 {
                     Directory.CreateDirectory(uploadpath);
                 }
                 string saveName = Encrypt.GenerateOrderNumber() + ".jpg";
                 var savePath = uploadpath + saveName;

                 try
                 {
                     mywebclient.DownloadFile(strpath, savePath);
                     return Json(new { Success = true, SaveName = path + saveName });
                 }
                 catch (Exception ex)
                 {
                     savePath = ex.ToString();
                 }

             }
             return Json(new {Success = false, Message = "上传失败！"});
        }