图片与byte相互转换

一、图片转byte

 public byte[]  ImageToByte()
        {
            string imagefile = @"http://192.168.0.212/pass/T-1.jpg";//互联网图片地址
            Image img = UrlToImage(imagefile);
            Bitmap bmp = new Bitmap(img);
            MemoryStream ms = new MemoryStream();
            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            byte[] arr = new byte[ms.Length];
            ms.Position = 0;
            ms.Read(arr, 0, (int)ms.Length);
            ms.Close();
            var a = Convert.ToBase64String(arr);
            string strbaser64 = "";
            WebClient mywebclient = new WebClient();
            byte[] Bytes = mywebclient.DownloadData(imagefile);
            return Bytes

        }
        public  Image UrlToImage(string url)
        {
            WebClient mywebclient = new WebClient();
            byte[] Bytes = mywebclient.DownloadData(url);
            using (MemoryStream ms = new MemoryStream(Bytes))
            {
                Image outputImg = Image.FromStream(ms);
                return outputImg;
            }
        }

二、byte转图片

将byte数组保存成图片：

方式一：System.IO.File.WriteAllBytes(@"c:\test.jpg", bytes);

方式二：MemoryStream ms=new MemoryStream(Byte[] b);  把那个byte[]数组传进去,然后
           FileStream fs=new FileStream(路径 例如:"E:\image\1.jpg");
　　　　ms.writeto(fs);
　　　　ms.close();
　　　　fs.close();

方法三：

       //得到图片地址
       var stringFilePath = context.Server.MapPath(string.Format("~/Image/{0}{1}.jpg", imageName, id));
       //声明一个FileStream用来将图片暂时放入流中
       FileStream stream = new FileStream(stringFilePath, FileMode.Open);
       using (stream)
       {
           //透过GetImageFromStream方法将图片放入byte数组中
           byte[] imageBytes = this.GetImageFromStream(stream,context);
           //上下文确定写到客户短时的文件类型
           context.Response.ContentType = "image/jpeg";
           //上下文将imageBytes中的数据写到前段
           context.Response.BinaryWrite(imageBytes);
           stream.Close();
        }