c# MD5校驗文件

 private string GetMd5Hash(string pathName)
        {
            string strResult = "";
            string strHashData = "";
            byte[] arrbytHashValue;

            System.IO.FileStream oFileStream = null;

            System.Security.Cryptography.MD5CryptoServiceProvider oMD5Hasher =
                new System.Security.Cryptography.MD5CryptoServiceProvider();

            try
            {
                oFileStream = new System.IO.FileStream(pathName, System.IO.FileMode.Open,
                                                       System.IO.FileAccess.Read, System.IO.FileShare.ReadWrite);

                arrbytHashValue = oMD5Hasher.ComputeHash(oFileStream); //計算指定Stream 對象的哈希值

                oFileStream.Close();

                //由以連字符分隔的十六進制對構成的String，其中每一對表示value 中對應的元素；例如“F-2C-4A”

                strHashData = System.BitConverter.ToString(arrbytHashValue);

                //替換-
                strHashData = strHashData.Replace("-", "");

                strResult = strHashData;
            }

            catch (System.Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            return strResult;
        }