.net c# 修改视频md5

修改视频的md5方法

[HttpPost]
        public dynamic GetData([FromBody]Model model)
        {
            try
            {
                string fileName = "D:/file/20200220231945.mp4";
                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"));
                }
                string url = "https://mvvideoshare2.meitudata.com/5dda4bec8817cone366kye5346_H264_4_b32d9269f3335a.mp4?k=248316b0ee01e2f28566d3fbee4fb59e&t=5e52972d";
                string newDate = DateTime.Now.ToString("yyyyMMddHHmmss");
                string tempPath = !string.IsNullOrEmpty(System.Configuration.ConfigurationManager.AppSettings["tempPath"]) ? System.Configuration.ConfigurationManager.AppSettings["tempPath"] : "D:\\video\\resource\\";
                string videoUrl = @tempPath + newDate + ".mp4";
                byte[] temp = GetBytesFromUrl(url);
                byte[] temp3 = new byte[temp.Length + 1];
                byte[] temp2 = new byte[1];
                temp.CopyTo(temp3, 0);
                temp2.CopyTo(temp3, temp.Length);
                string path = videoUrl;
                WriteBytesToFile(videoUrl, temp3);
                return sb.ToString();
            }
            catch (Exception ex)
            {
                throw new Exception("GetMD5HashFromFile() fail,error:" + ex.Message);
            }
            return null;
        }

        /// 

        /// 获取文件MD5值
        /// 
        /// 文件绝对路径
        /// MD5值

        [HttpPost]
        public string GetMD5HashFromFile()
        {
            try
            {
                string fileName = "D:/file/20200220231945.mp4";
                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);
            }
        }