如何通过webclient下载图像(jpg)并保存到Windows Phone 7上的独立存储？

using System.IO;
using System.IO.IsolatedStorage;
using System.Net;

private void downloadButton_Click(object sender, RoutedEventArgs e)
{
    string imageUrl = imageUrlTextBox.Text;
    WebClient webClient = new WebClient();
    webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(webClient_OpenReadCompleted);
    webClient.OpenReadAsync(new Uri(imageUrl));
}

private void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
    if (e.Error == null && !e.Cancelled)
    {
        Stream imageStream = e.Result;
        IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication();
        string imagePath = "isolatedStorage/myImage.jpg";
        using (IsolatedStorageFileStream fileStream = storage.CreateFile(imagePath))
        {
            int byteSize = 4096;
            byte[] bytes = new byte[byteSize];
            int bytesRead = 0;
            while ((bytesRead = imageStream.Read(bytes, 0, byteSize)) != 0)
            {
                fileStream.Write(bytes, 0, bytesRead);
            }
        }
        imageControl.Source = new BitmapImage(new Uri(imagePath, UriKind.Relative));
    }
}