C# Image and Base64 Conversion and Storage

        /// <summary>
        /// base64转为图片存储到本地
        /// </summary>
        /// <param name="base64"></param>
	    /// <param name="imagesPath"></param>
        /// <returns></returns>
        public static async Task<string> ImageToFile(string base64,string imagesPath)
        {
            if (String.IsNullOrEmpty(base64)) return null;
			
			// 修改字符串操作部分
            int base64Index = base64.IndexOf("base64,");
            if (base64Index < 0)
                return null;

            string imageType = base64.Substring(0, base64Index);
            string imageContent = base64.Substring(base64Index + 7); // Skip "base64,"

            if (!Directory.Exists(imagesPath))
                Directory.CreateDirectory(imagesPath);

            byte[] response = Convert.FromBase64String(imageContent);
            if (response.Length <= 0) return null;

            string name = DateTime.Now.Ticks.ToString();

            if (imageType == "data:image/jpg;")
                name += ".jpg";
            else if (imageType == "data:image/png;")
                name += ".png";
            else
                return null;

            using (FileStream fs = new FileStream(Path.Combine(imagesPath, "/", name), FileMode.Create, FileAccess.Write))
            {
                await fs.WriteAsync(response);
                await fs.FlushAsync();
                fs.Close();
            }
            return name;
        }

获取图片 md5 值

        /// <summary>
        /// 获取文件MD5值
        /// </summary>
        /// <param name="fileName">文件绝对路径</param>
        /// <returns>MD5值</returns>
        public static string GetMD5HashFromFile(string fileName)
        {
            try
            {
                FileStream file = new FileStream(fileName, FileMode.Open);
                System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
                byte[] retVal = md5.ComputeHash(file);
                file.Close();

                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < retVal.Length; i++)
                {
                    sb.Append(retVal[i].ToString("x2"));
                }
                return sb.ToString();
            }
            catch (Exception ex)
            {
                throw new Exception("GetMD5HashFromFile() fail,error:" + ex.Message);
            }
        }

图片文件生成base64：

        private static string GetBase64(string imagePath)
        {
            string result = Convert.ToBase64String(File.ReadAllBytes(imagePath));
            // 不需要替换了，因为返回的字符串不包含前缀
            return result;
        }

base64转存图片到本地

static async Task Test(string base64){
 if (String.IsNullOrEmpty(base64)) return;
            byte[] response = Convert.FromBase64String(base64);

            if (!(response.Length > 0)) return;
            if (!Directory.Exists(dirpath)) Directory.CreateDirectory(dirpath);

            using (FileStream fs = new FileStream(dirpath + "/" + "原图" + aa + ".jpg", FileMode.Create, FileAccess.Write))
            {
                await fs.WriteAsync(response);
                await fs.FlushAsync();
                fs.Close();
            }
}