如何存储从网络接收的图像并将其显示在Windows Phone 7应用程序中

这是有关如何执行此操作的示例。逻辑如下：

1. 在页面的构造函数中，调用LoadImage方法。
2. 如果可用，该方法会将imageBrush的ImageSource设置为独立存储中的图像。
3. 如果隔离存储中不存在该映像，则LoadImage方法将从Web下载该映像，并在下载完成后调用事件处理程序。
4. 然后，事件处理程序（DownloadCompleted方法）将图像保存到隔离存储中，然后LoadImage再次调用。下一步将参考第2点。

您可能需要稍后对其进行改进，以实现MVVM和使用DataBinding。

参考：nickharris.net，geekchamp.com

string imageName = "myImage.jpg";
string imageUrl = "http://political-leader.vzons.com/ArvindKejriwal/images/icons/landing.png";

public MainPage()
{
    InitializeComponent();
    LoadImage();
}

private void LoadImage()
{
    BitmapImage bi = new BitmapImage();
    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //load image from Isolated Storage if it already exist
        if (myIsolatedStorage.FileExists(imageName))
        {
            using (IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile(imageName, FileMode.Open, FileAccess.Read))
            {
                bi.SetSource(fileStream);
                imageBrushName.ImageSource = bi;
            }
        }
        //else download image to Isolated Storage
        else
        {
            WebClient wc = new WebClient();
            wc.OpenReadCompleted += new OpenReadCompletedEventHandler(DownloadCompleted);
            wc.OpenReadAsync(new Uri(imageUrl, UriKind.Absolute), wc);
        }
    }
}

private void DownloadCompleted(object sender, OpenReadCompletedEventArgs e)
{
    if (e.Error == null && !e.Cancelled)
    {
        try
        {
            using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(imageName);

                BitmapImage bitmap = new BitmapImage();
                bitmap.SetSource(e.Result);
                WriteableBitmap wb = new WriteableBitmap(bitmap);

                // Encode WriteableBitmap object to a JPEG stream.
                Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
                fileStream.Close();
            }
            //after image saved to Iso storage, call LoadImage method again
            //so the method will set imageBrush's ImageSource to image in Iso storage
            LoadImage();
        }
        catch (Exception ex)
        {
            //Exception handle appropriately for your app  
        }
    }
    else
    {
        //Either cancelled or error handle appropriately for your app  
    }
}