如何在 C# 中从数据库检索时将 varBinary 转换为图像或视频

Question

我正在使用 Visual Studio 2010（桌面应用程序）并使用 LINQ to SQL 将图像/视频或音频文件保存到数据类型 VarBinary (MAX) 的数据库中。我可以做到这一点...问题是，我无法获取它们并在 xaml 中显示它们，因为我无法正确获取转换部分。这是我到目前为止所拥有的（尽管它不起作用）；

    private void bt_Click (object sender, RoutedEventArgs e)
    {
       databaseDataContext context = new databaseDataContext();

        var imageValue = from s in context.Images
                            where s.imageID == 2
                            select s.imageFile;

        value = imageValue.Single().ToString();        
        //convert to string and taking down to next method to get converted in image
    }

    public string value { get; set; }


    public object ImageSource //taking from http://stackoverflow.com/
    {
        get
        {
            BitmapImage image = new BitmapImage();
            try
            {
                image.BeginInit();
                image.CacheOption = BitmapCacheOption.OnLoad;
                image.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
                image.UriSource = new Uri(value, UriKind.Absolute);
                image.EndInit();

                Grid.Children.Add(image);
            }
            catch { return DependencyProperty.UnsetValue; } return image;
        }

    } 

我什至不确定我是否走在正确的轨道上？我假设视频或音频是非常相似的方法？

Answer 1

由于图像以二进制格式存储在数据库中，因此您希望通过利用 MemoryStream 对象将其“流”到图像对象中。

查看您的代码，您的解决方案将如下所示：

BitmapImage bmpImage = new BitmapImage();
MemoryStream msImageStream = new MemoryStream();    

msImageStream.Write(value, 0, value.Length);

bmpCardImage.BeginInit();
bmpCardImage.StreamSource = new MemoryStream(msImageStream.ToArray());
bmpCardImage.EndInit();

image.Source = bmpCardImage;

Answer 2

这很简单，如果您有二进制数据并想要创建 Image 对象，请使用以下代码：

public Image BinaryToImage(byte[] binaryData)
{
     MemoryStream ms = new MemoryStream(binaryData);
     Image img = Image.FromStream(ms);
     return img;
}

Answer 3

如果您已经有了字节，要验证您保存的内容是否正确，您可以将字节保存到文件中并打开它......

string tempFile = Path.GetTempFileName();
MemoryStream ms = new MemoryStream(bytes); //bytes that was read from the db
//Here I assume that you're reading a png image, you can put any extension you like is a file name
FileStream stream = new FileStream(tempFile + ".png", FileMode.Create);
ms.WriteTo(stream);
ms.Close();
stream.Close();
//And here we open the file with the default program
Process.Start(tempFile + ".png");

稍后您可以使用 Dillie-O 的答案和流......

Answer 4

Dillie-O 的代码构成了一个非常好的扩展方法：

    // from http://stackoverflow.com/questions/5623264/how-to-convert-varbinary-into-image-or-video-when-retrieved-from-database-in-c:
    public static BitmapImage ToImage(this Binary b)
    {
        if (b == null)
            return null;

        var binary = b.ToArray();
        var image = new BitmapImage();
        var ms = new MemoryStream();

        ms.Write(binary, 0, binary.Length);

        image.BeginInit();
        image.StreamSource = new MemoryStream(ms.ToArray());
        image.EndInit();

        return image;
    }