/// <summary>
 /// 暂停,继续下载
 /// </summary>
 /// <param name="bstop"></param>
 public void myTaskReStart(bool bstop)
 {
     try
     {
         if (bstop)
         {
             if (bolDownloadingFlag)
             {
                 //webcDownloading.Suspend()
                 if (webcDownloading.IsBusy)
                 {
                     //取消异步下载
                     webcDownloading.CancelAsync();
                     //异步取消,直到IsBusy为False
                     while (webcDownloading.IsBusy)
                     {
                         //do something
                         if (bolItemDestroyed)
                         {
                             break;
                         }
                     }
                 }
             }
         }
         else
         {
             // '如果开启了下载,且下载任务EventDone状态不为已完成,则继续下载,
             // 'WebClient的异步下载文件已修改为支持断点续传
             if (bolDownloadingFlag)
             {
                 //已修改WebClient增加断点续传
                 DownloadFileAsync(this.DownloadUrl);
             }
         }
     }
     catch (Exception ex)
     {
     }
 }