how to download only specific file from ftp server

i am downloading file from ftp server to local folder and after that i am reading those file from the folder to ax table

the problem is i want to filter some file on the basis of file extension while downloading 

i am using the code to download file from ftp server.

private void ftpDownloadAllFiles()
{
str fileNameType;

FilePath filePathDest;
;
saveToFilePath= local file path;
fileNameType=".R102";
ftpHostName= "ftp path";
// info("weqd");
this.getFTPDirFilesList();
//info("weq1");
ftpFilesListEnum = ftpFilesList.getEnumerator();
ftpFilesListEnum.reset();

while (ftpFilesListEnum.moveNext())
{
fileNameType = ftpFilesListEnum.current();
//info("weq");
// Marshaling .NET to X++
ftpObject = System.Net.WebRequest::Create(ftpHostName + @"/" + fileNameType);
ftpWebRequest = ftpObject;

if (ftpWebRequest)
{
ftpWebRequest.set_KeepAlive(false);
ftpWebRequest.set_UsePassive(true);
ftpWebRequest.set_UseBinary(true);
//ftpWebRequest.set_Timeout(ftpTimeOut);
ftpWebRequest.set_Method(#DownloadFile);
//ftpWebRequest.set_ReadWriteTimeout(ftpTimeOut);
this.setFTPCredentials();

ftpWebResponse = ftpWebRequest.GetResponse();
//info("weqq4");
// BP Deviation Documented
ioStreamReader = new System.IO.StreamReader(ftpWebResponse.GetResponseStream());

if (ioStreamReader)
{
strReadLine = ioStreamReader.ReadToEnd();

if (strReadLine)
{
filePathDest = saveToFilePath + @"\" + fileNameType;
this.writeFile(filePathDest);

info(strfmt("Downloaded file %1 to %2", fileNameType, saveToFilePath));
}

ioStreamReader.Close();
}
}
}
}