sql-server - 将 jpg 数据从数据库保存到 jpg 文件

Question

我想获取包含 jpeg 图像的字段中的数据并将其保存到可以使用绘图编辑器打开的实际文件中。我知道我可以在 c# 中创建一个应用程序来执行此操作，但我想知道是否有一种快速简便的方法可以从 sql 查询中执行此操作？

它不需要同时处理所有记录。我只需要能够选择一条记录并将该记录的图像保存到文件中。

Answer 1

您可以在 C# 中使用 MemoryStream 对象，如下所示

MemoryStream memstmSignature = new MemoryStream(InkToBytes(ds.Tables[1].Rows[0]["SIGNATURE"].ToString(), "image/gif", 0, 0));
Image imaSig = Image.FromStream(memstmSignature);
imaSig.RotateFlip(RotateFlipType.Rotate180FlipX);
imaSig.Save(Path.Combine(this.temporaryFilePath, this.signatureFileName));
memstmSignature.Close();

private static byte[] InkToBytes(string inkStrokes, string encoderType, float x, float y) { ArrayList strokes = new ArrayList(); 下面的辅助函数

        // max size for bit map
        int maxX = 0;
        int maxY = 0;

        // intialize the strokes array with text string
        int strokesCount;
        if (inkStrokes.Length > 0)
        {
            if (inkStrokes.EndsWith(";"))
                inkStrokes = inkStrokes.Remove((inkStrokes.Length - 1), 1);

            char[] strokeSeperator = { ';' };
            string[] strokeArray = inkStrokes.Split(strokeSeperator);
            strokesCount = strokeArray.Length;

            for (int i = 0; i < strokesCount; i++)
            {
                Stroke stroke = new Stroke(50);
                stroke.Text = strokeArray[i];
                strokes.Add(stroke);

                Point[] points = stroke.ToPointArray();
                int len = points.Length;
                foreach (Point point in points)
                {
                    maxX = (point.X > maxX ? point.X : maxX);
                    maxY = (point.Y > maxY ? point.Y : maxY);
                }
            }
        }

        // setup the gdi objects
        Bitmap bitMap = new Bitmap(maxX + 20, maxY + 20); // leave some buffer room
        Graphics graphics = Graphics.FromImage(bitMap);
        Rectangle clientRect = new Rectangle(0, 0, bitMap.Width, bitMap.Height);
        Pen pen = new Pen(Color.Black);
        pen.Width = 2; // matches the client capture

        // draw the bit map
        if (x > 0 && y > 0)
            graphics.DrawImage(bitMap, x, y);
        else
            graphics.DrawImage(bitMap, 0, 0);
        graphics.FillRectangle(Brushes.White, clientRect);
        graphics.DrawRectangle(pen, clientRect);
        strokesCount = strokes.Count;
        for (int j = 0; j < strokesCount; j++)
        {
            Stroke stroke = (Stroke)strokes[j];
            if (stroke != null)
            {
                Point[] points = stroke.ToPointArray();
                int len = points.Length;
                if (len > 1)
                {
                    Point prevPoint = points[0];
                    for (int i = 1; i < len; i++)
                    {
                        graphics.DrawLine(pen, prevPoint.X, prevPoint.Y, points[i].X, points[i].Y);
                        prevPoint = points[i];
                    }
                }
            }
        }

        // create the bytes from the bitmap to be returned
        MemoryStream memStream = new MemoryStream(1000);
        ImageCodecInfo imageCodedInfo = GetEncoderInfo(encoderType);
        bitMap.Save(memStream, imageCodedInfo, null);
        byte[] bytes = memStream.GetBuffer();
        memStream.Close();
        return bytes;
    }

    private static ImageCodecInfo GetEncoderInfo(String mimeType)
    {
        int j;
        ImageCodecInfo[] encoders;
        encoders = ImageCodecInfo.GetImageEncoders();
        for (j = 0; j < encoders.Length; ++j)
        {
            if (encoders[j].MimeType == mimeType)
                return encoders[j];
        }
        return null;
    }

希望这可以帮助。注意：我没有考虑优化上面的代码