C# 二进制图片串互转

C# byte数组与Image的相互转换

 

功能需求：

1、把一张图片（png bmp jpeg bmp gif）转换为byte数组存放到数据库。

2、把从数据库读取的byte数组转换为Image对象，赋值给相应的控件显示。

3、从图片byte数组得到对应图片的格式，生成一张图片保存到磁盘上。

这里的Image是System.Drawing.Image。

    //Get an image from file
     Image image = Image.FromFile("D:\\test.jpg");
     Bitmap bitmap = new Bitmap("D:\\test.jpg");

以下三个函数分别实现了上述三个需求：

 using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
 using System.Linq;
 using System.Text;

 namespace NetUtilityLib
 {
     public static class ImageHelper
     {
         /// <summary>
         /// Convert Image to Byte[]
         /// </summary>
         /// <param name="image"></param>
         /// <returns></returns>
         public static byte[] ImageToBytes(Image image)
         {
             ImageFormat format = image.RawFormat;
             using (MemoryStream ms = new MemoryStream())
             {
                 if (format.Equals(ImageFormat.Jpeg))
                 {
                     image.Save(ms, ImageFormat.Jpeg);
                 }
                 else if (format.Equals(ImageFormat.Png))
                 {
                     image.Save(ms, ImageFormat.Png);
                 }
                 else if (format.Equals(ImageFormat.Bmp))
                 {
                     image.Save(ms, ImageFormat.Bmp);
                 }
                 else if (format.Equals(ImageFormat.Gif))
                 {
                     image.Save(ms, ImageFormat.Gif);
                 }
                 else if (format.Equals(ImageFormat.Icon))
                 {
                     image.Save(ms, ImageFormat.Icon);
                 }
                 byte[] buffer = new byte[ms.Length];
                 //Image.Save()会改变MemoryStream的Position，需要重新Seek到Begin
                 ms.Seek(, SeekOrigin.Begin);
                 ms.Read(buffer, , buffer.Length);
                 return buffer;
             }
         }

         /// <summary>
         /// Convert Byte[] to Image
         /// </summary>
         /// <param name="buffer"></param>
         /// <returns></returns>
         public static Image BytesToImage(byte[] buffer)
         {
             MemoryStream ms = new MemoryStream(buffer);
             Image image = System.Drawing.Image.FromStream(ms);
             return image;
         }

         /// <summary>
         /// Convert Byte[] to a picture and Store it in file
         /// </summary>
         /// <param name="fileName"></param>
         /// <param name="buffer"></param>
         /// <returns></returns>
         public static string CreateImageFromBytes(string fileName, byte[] buffer)
         {
             string file = fileName;
             Image image = BytesToImage(buffer);
             ImageFormat format = image.RawFormat;
             if (format.Equals(ImageFormat.Jpeg))
             {
                 file += ".jpeg";
             }
             else if (format.Equals(ImageFormat.Png))
             {
                 file += ".png";
             }
             else if (format.Equals(ImageFormat.Bmp))
             {
                 file += ".bmp";
             }
             else if (format.Equals(ImageFormat.Gif))
             {
                 file += ".gif";
             }
             else if (format.Equals(ImageFormat.Icon))
             {
                 file += ".icon";
             }
             System.IO.FileInfo info = new System.IO.FileInfo(file);
             System.IO.Directory.CreateDirectory(info.Directory.FullName);
             File.WriteAllBytes(file, buffer);
             return file;
         }
     }
 }