public static 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.Replace("\\"", ""), System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.ReadWrite);
  
        arrbytHashValue = oMD5Hasher.ComputeHash(oFileStream); //计算指定Stream 对象的哈希值
  
        oFileStream.Close();
  
        //由以连字符分隔的十六进制对构成的String，其中每一对表示value 中对应的元素；例如“F-2C-4A”
  
        strHashData = System.BitConverter.ToString(arrbytHashValue);
  
        //替换-
        strHashData = strHashData.Replace("-", "");
  
        strResult = strHashData;
    }
  
    catch (System.Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
    return strResult;
}