在這資源更新的進度條顯示時

            using (WebClient client = new WebClient()) {
                sw.Start();
                client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);
                client.DownloadFileAsync(new System.Uri(url), currDownFile);
            }

註冊上進度條下載的委託和下載完成的委託就可以了

在更新進度條的委託中可以得到下載的進度條和下載的總大小以及已經下載的大小。

用e.UserState可以取到傳入的引數，由於是下載檔案有可能下載多個但是更新進度條的方法都走的一個方法所以需要用UserState來取得對應下載任務的進度條。

下面貼一下這兩個委託的實現方法，我將WebClient簡單封裝了一下。

private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e) {
        //下載的總量
        PrecentData preData = new PrecentData();
        preData.total = string.Format("{0} MB / {1} MB"
 
, (e.BytesReceived / 1024d / 1024d).ToString("0.00"),  (e.TotalBytesToReceive / 1024d / 1024d).ToString("0.00"));
        preData.precent = (float)e.BytesReceived / (float)e.TotalBytesToReceive;



            string value = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));

        preData.speed = value;

        Loom.QueueOnMainThread((param) =>
        {
            NotificationCenter.Get().ObjDispatchEvent(KEventKey.m_evDownload, preData);
        }, null
 
);


            NotiData data = new NotiData(NotiConst.UPDATE_PROGRESS, value);
            if (m_SyncEvent != null) m_SyncEvent(data);

            if (e.ProgressPercentage == 100 && e.BytesReceived == e.TotalBytesToReceive) {
                sw.Reset();

                data = new NotiData(NotiConst.UPDATE_DOWNLOAD, currDownFile);
                if (m_SyncEvent != null) m_SyncEvent(data);
            }
        }

要顯示下載百分比使用

string.Format("{0} MB / {1} MB", (e.BytesReceived / 1024d / 1024d).ToString("0.00"),  (e.TotalBytesToReceive / 1024d / 1024d).ToString("0.00"));

要顯示當前的下載速度

string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));