public static class Base64Helper
    {
        /// <summary>
        /// base64字符保存图片到本
        /// </summary>
        /// <param name="filePath">保存的图片完整路径</param>
        /// <param name="base64String">base64字符串</param>
        public static void Base64SaveImage(string filePath, string base64String)
        {
            try
            {
                //如果base64是通过http传过来的，要注意其中的%、，、空格等转换，C#规定base64的长度必须是4的倍数，有个别语言是2的倍数，补上==。
                base64String = base64String.Trim().Replace("%", "").Replace(",", "").Replace(" ", "+");
                if (base64String.Length % 4 != 0)
                {
                    base64String += "==";
                }
                byte[] arr2 = Convert.FromBase64String(base64String);
                using (MemoryStream ms2 = new MemoryStream(arr2))
                {
                    System.Drawing.Bitmap bmp2 = new System.Drawing.Bitmap(ms2);
                    bmp2.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
                    bmp2.Dispose();
                }
            }
            catch (Exception ex)
            {
                LogHelper.WriteLog("图片保存异常：" + ex.ToString());
            }
        }
        public static string ImgToBase64String(string Imagefilename)
        {
            try
            {
                Bitmap bmp = new Bitmap(Imagefilename);
                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)
            {
                LogHelper.WriteLog("图片读取异常：" + ex.ToString());
                return null;
            }
        }
        public static string ImageToBase64(string path)
        {
            byte[] bytes = GetPictureData(path);
            string base64 = Convert.ToBase64String(bytes);
            return base64;
        }
        public static Bitmap Base64ToImage(string base64)
        {
            byte[] arr = Convert.FromBase64String(base64);
            MemoryStream ms = new MemoryStream(arr);
            Bitmap bmp = new Bitmap(ms);
            ms.Close();
            return bmp;
        }
        public static byte[] GetPictureData(string imagePath)
        {
            FileStream fs = new FileStream(imagePath, FileMode.Open);
            byte[] byData = new byte[fs.Length];
            fs.Read(byData, 0, byData.Length);
            fs.Close();
            return byData;
        }
    }