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        #region base64转图片

        /// <summary>

        /// 图片上传 Base64解码

        /// </summary>

        /// <param name="dataURL">Base64数据</param>

        /// <param name="imgName">图片名字</param>

        /// <returns>返回一个相对路径</returns>

        public string decodeBase64ToImage(string dataURL,string imgName)

        {

            string filename = "";//声明一个string类型的相对路径

            String base64 = dataURL.Substring(dataURL.IndexOf(",") + 1);      //将‘，’以前的多余字符串删除

            System.Drawing.Bitmap bitmap = null;//定义一个Bitmap对象，接收转换完成的图片

            try//会有异常抛出，try，catch一下

            {

                byte[] arr = Convert.FromBase64String(base64);//将纯净资源Base64转换成等效的8位无符号整形数组

                System.IO.MemoryStream ms = new System.IO.MemoryStream(arr);//转换成无法调整大小的MemoryStream对象

                bitmap = new System.Drawing.Bitmap(ms);//将MemoryStream对象转换成Bitmap对象

                filename ="Knowledge_" + imgName + ".jpg";//所要保存的相对路径及名字

                string url =HttpRuntime.AppDomainAppPath.ToString();

                string tmpRootDir = System.Web.HttpContext.Current.Server.MapPath(System.Web.HttpContext.Current.Request.ApplicationPath.ToString()); //获取程序根目录 

                string imagesurl2 = tmpRootDir + filename; //转换成绝对路径 

                bitmap.Save(imagesurl2, System.Drawing.Imaging.ImageFormat.Jpeg);//保存到服务器路径

                //bitmap.Save(filePath + ".bmp", System.Drawing.Imaging.ImageFormat.Bmp);

                //bitmap.Save(filePath + ".gif", System.Drawing.Imaging.ImageFormat.Gif);

                //bitmap.Save(filePath + ".png", System.Drawing.Imaging.ImageFormat.Png);

                ms.Close();//关闭当前流，并释放所有与之关联的资源

                bitmap.Dispose();

            }

            catch (Exception e)

            {

               string massage= e.Message;

            }

            return filename;//返回相对路径

        }

        #endregion

        #region 图片转base64

        /// <summary>

        /// 图片转base64

        /// </summary>

        /// <param name="path">图片路径</param><br>        /// <returns>返回一个base64字符串</returns>

        public string decodeImageToBase64(string path) {

            path = "E:/vs 2015/newaqtcprj/WEB/UpFile/2018/12/20181229174708_7471722c425a2ec08fa513ddf4f8c76306d55fbb0fbd9d8.jpg";

            string base64str = "";

            //站点文件目录

            string fileDir = HttpContext.Current.Server.MapPath("/");

            string[] arrfileDir = fileDir.Split('\\');

            fileDir = arrfileDir[0] + "\\" + arrfileDir[1] + "\\" + arrfileDir[2];

            try

            {

                //读图片转为Base64String

                System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(Path.Combine(fileDir, "WEB\\UpFile\\2018\\12\\20181229174708_7471722c425a2ec08fa513ddf4f8c76306d55fbb0fbd9d8.jpg"));

                //System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(path);

                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();

                bmp.Dispose();

                base64str = Convert.ToBase64String(arr);

            }

            catch (Exception e)

            {

                string mss = e.Message;

            }

            return "data:image/jpg;base64," + base64str;

        }

        #endregion