• 图片和Base64字符串互转


    图片URL转成Base64字符串

    /// <summary>
            /// 通过Url获取到Image格式的文件
            /// </summary>
            /// <param name="url"></param>
            /// <returns></returns>
            public static 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;
                }
            }
            /// <summary>
            /// 再将Iamge文件转为Base64字符串
            /// </summary>
            /// <param name="img"></param>
            /// <returns></returns>
            public static string BitmapToBase64(Image img)
            {
                System.Drawing.Bitmap bitMap = new System.Drawing.Bitmap(img);
                string imgBase64 = string.Empty;
                using (MemoryStream memoryStream = new MemoryStream())
                {
                    bitMap.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                    byte[] buffer = new byte[memoryStream.Length];
                    memoryStream.Position = 0;
                    memoryStream.Read(buffer, 0, (int)memoryStream.Length);
                    memoryStream.Close();
                    imgBase64 = Convert.ToBase64String(buffer);
                }
                return imgBase64;
            }
    

      Base64字符串转成图片并保存

    /// <summary>
            /// 将Base64String转为图片并保存
            /// </summary>
            /// <param name="imgBase64"></param>
            public static void Base64ToImage(string imgBase64)
            {
                string format;
                string imgPath = Directory.GetCurrentDirectory() + "\" + DateTime.Now.ToString("yyyyMMddHHmmss");
                byte[] buffer = Convert.FromBase64String(imgBase64);
                using (MemoryStream memoryStream = new MemoryStream(buffer))
                {
                    System.Drawing.Bitmap bitMap = new System.Drawing.Bitmap(memoryStream);
                    System.Drawing.Imaging.ImageFormat imgFormat = GetImageFormat(memoryStream, out format);
                    imgPath = imgPath + format;
                    bitMap.Save(imgPath, imgFormat);
                    bitMap.Dispose();
                }
            }
            /// <summary>
            /// 获取Image图片格式
            /// </summary>
            /// <param name="file"></param>
            /// <param name="format"></param>
            /// <returns></returns>
            private static System.Drawing.Imaging.ImageFormat GetImageFormat(MemoryStream file, out string format)
            {
                byte[] sb = new byte[2];  //这次读取的就是直接0-1的位置长度了.
                file.Read(sb, 0, sb.Length);
                //根据文件头判断
                string strFlag = sb[0].ToString() + sb[1].ToString();
                //察看格式类型
                switch (strFlag)
                {
                    //JPG格式
                    case "255216":
                        format = ".jpg";
                        return System.Drawing.Imaging.ImageFormat.Jpeg;
                    //GIF格式
                    case "7173":
                        format = ".gif";
                        return System.Drawing.Imaging.ImageFormat.Gif;
                    //BMP格式
                    case "6677":
                        format = ".bmp";
                        return System.Drawing.Imaging.ImageFormat.Bmp;
                    //PNG格式
                    case "13780":
                        format = ".png";
                        return System.Drawing.Imaging.ImageFormat.Png;
                    //其他格式
                    default:
                        format = ".jpg";
                        return System.Drawing.Imaging.ImageFormat.Jpeg;
                }
            } 
    

      调用

     static void Main(string[] args)
            {
                //string imgUrl = "D:\c29e09b0-e5f4-43fa-9ded-8f9865a2e8d4.jpg";
                //string imgUrl = "https://www.baidu.com/img/superlogo_c4d7df0a003d3db9b65e9ef0fe6da1ec.png";
                string imgUrl = "http://file02.16sucai.com/d/file/2015/0408/779334da99e40adb587d0ba715eca102.jpg";//图片可以是本地磁盘地址、可以是http和https地址
                Image img = UrlToImage(imgUrl);//转成Image格式
                string imgBase64 = BitmapToBase64(img); //注意:生成的Base64字符串加上  data:image/jpeg;base64,  可以在前端识别
                Base64ToImage( imgBase64);//生成图片并保存
              
                Console.ReadKey();
            }
    

      

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  • 原文地址:https://www.cnblogs.com/qidakang/p/12022683.html
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