图片和字节数组的相互转换

为存储和读取方便，经常需要将图片以字节数组形式存储到数据库，或者从数据库读取图片的字节数组数据还原为图片，可以定义一个转换类，方便调用。

public static class Img2Byte
    {
        /// <summary>
        /// 从图像转换为字节数组
        /// </summary>
        /// <param name="img">Image对象</param>
        /// <returns>字节数组</returns>
        public static byte[] getByteFromImage(Image img)
        {
            byte[] imgByte = null;
            using (MemoryStream ms = new MemoryStream())
            {
                img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                imgByte = ms.GetBuffer();
            }
            return imgByte;
        }

        /// <summary>
        /// 从字节数组转换为图像
        /// </summary>
        /// <param name="imgByte">字节数组</param>
        /// <returns>Image对象</returns>
        public static Image getImageFromByte(byte[] imgByte)
        {
            Image img = null;
            if (imgByte.Length == 0)
                return null;
            using (MemoryStream ms = new MemoryStream(imgByte))
            {
                img = Image.FromStream(ms);
            }
            return img;
        }

        /// <summary>
        /// 从图片路径转为字节数组
        /// </summary>
        /// <param name="imgFilePath">图片完整路径</param>
        /// <returns>字节数组</returns>
        public static byte[] getByteFromImgFile(string imgFilePath)
        {
            if(!File.Exists(imgFilePath))
                return null;
            FileStream fs = new FileStream(imgFilePath, FileMode.Open, FileAccess.Read);
            long length = fs.Length;
            byte[] imgByte = new byte[length];
            fs.Read(imgByte, 0, imgByte.Length);
            fs.Close();
            return imgByte;
        }

    }