C# 网络图片转base64

#region Image To base64
        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>
        /// Image 转成 base64
        /// </summary>
        /// <param name="fileFullName"></param>
        public static string ImageToBase64(Image img)
        {
            try
            {
                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();
                return Convert.ToBase64String(arr);
            }
            catch (Exception ex)
            {
                return null;
            }
        }
        public static string ImageToBase64(string url)
        {
            return ImageToBase64(UrlToImage(url));
        }
        #endregion

调用

ImageToBase64(url)