将网络资源写入WP7隔离存储空间

private void DownloadFile(string uri, string filename)
{
 var wc = new WebClient();
 wc.OpenReadAsync(new Uri(uri), filename);
 wc.OpenReadCompleted += new OpenReadCompletedEventHandler(wc_OpenReadCompleted);
}

void wc_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
 if (e.Error != null) return;

 var filename = e.UserState.ToString();
 var str = e.Result;

 using (var myStore = IsolatedStorageFile.GetUserStoreForApplication())
 {
  if (myStore.FileExists(filename)) myStore.DeleteFile(filename);

  var buffer = new byte[1024];
  using (var isoStorStr = myStore.OpenFile(filename, FileMode.CreateNew))
  {
   int bytesRead = 0;
   while ((bytesRead = str.Read(buffer, 0, 1024)) > 0)
    isoStorStr.Write(buffer, 0, bytesRead);
  }
 }
}