从FTP下载文件时遇到如下问题,如何破?

/// <summary>

/// 从Ftp下载文件

/// </summary>

/// <param name="fileName">文件名(完整名,如test.rar)</param>

/// <param name="bufferSize">每次下载大小(byte)</param>

public static void Download(string fileName,int bufferSize)

{			

	FtpFileUploadConfig config=new FtpFileUploadConfig();

	string path = ConfigurationManager.AppSettings["UploadPath"];

	HttpResponse httpResponse=HttpContext.Current.Response;

	FtpWebRequest ftpRequest = WebRequest.Create(config.GetFtpUri(path)+"/"+fileName) as FtpWebRequest;

	ftpRequest.Credentials = new NetworkCredential(config.UserName, config.Password);

	ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile;

	

	using (FtpWebResponse ftpResponse = ftpRequest.GetResponse() as FtpWebResponse)

	{

		Stream data = ftpResponse.GetResponseStream();

		//文件总大小

		long dataLength = ftpResponse.ContentLength;

		//每次下载的大小

		byte[] buffer = new byte[bufferSize];

		httpResponse.Clear();

		httpResponse.ContentType = "application/octet-stream";

		httpResponse.AddHeader("Content-Disposition", "attachment; filename=" + fileName);

		int readCount;

		do

		{

			readCount = data.Read(buffer, 0, bufferSize);

			httpResponse.OutputStream.Write(buffer, 0, readCount);

			httpResponse.Flush();

		}

		while (readCount > 0);



		httpResponse.Close();

	}

}