在浏览器中从FTP下载文件

     public static class FTPHelper
     {
         /// <summary>
         /// 得到特定FTP目录的文件列表
         /// </summary>
         /// <param name="uri">ftp://{username}:{password}@ftp.baidu.com/{folderName}</param>
         public static List<String> ListFiles(Uri serverUri)
         {
             // The serverUri parameter should start with the ftp:// scheme.
             if (serverUri.Scheme != Uri.UriSchemeFtp)
             {
                 throw new ArgumentException("uri must be ftp scheme");
             }

             FtpWebRequest ftpRequest = null;
             StreamReader reader = null;
             try
             {
                 // Get the object used to communicate with the server.
                 ftpRequest = (FtpWebRequest)FtpWebRequest.Create(serverUri);

                 ftpRequest.Method = WebRequestMethods.Ftp.ListDirectory;

                 reader = new StreamReader(ftpRequest.GetResponse().GetResponseStream(), Encoding.Default);

                 //read data.
                 List<String> fileNames = new List<String>();
                 string line = reader.ReadLine();
                 while (line != null)
                 {

                     fileNames.Add(line);
                     line = reader.ReadLine();
                 }

                 return fileNames;

             }
             catch(Exception ex)
             {
                 throw ex;
             }
             finally
             {
               if(reader != null)
               {
                   reader.Close();
               }
               if (ftpRequest != null)
               {
                   ftpRequest.Abort();
               }
             }
         }

         /// <summary>
         /// 得到特定文件的大小
         /// </summary>
         /// <param name="uri">ftp://{username}:{password}@ftp.baidu.com/{fileName}</param>
         public static long GetFileSize(Uri serverUri)
         {
             // The serverUri parameter should start with the ftp:// scheme.
             if (serverUri.Scheme != Uri.UriSchemeFtp)
             {
                 throw new ArgumentException("uri must be ftp scheme");
             }

             FtpWebRequest ftpRequest = null;
             StreamReader reader = null;
             try
             {
                 // Get the object used to communicate with the server.
                 ftpRequest = (FtpWebRequest)FtpWebRequest.Create(serverUri);

                 ftpRequest.Method = WebRequestMethods.Ftp.GetFileSize;

                 return ftpRequest.GetResponse().ContentLength;
             }
             catch (Exception ex)
             {
                 throw ex;
             }
             finally
             {
                 if (reader != null)
                 {
                     reader.Close();
                 }
                 if (ftpRequest != null)
                 {
                     ftpRequest.Abort();
                 }
             }
         }
     }

调用ListFile方法把FTP特定目录的所有文件列表显示在web页面上，当单击名称时，下载文件

        /// <summary>
        /// 下载文件（此方法定义在实现Controller某类的某个MVC Controller中）
        /// </summary>
        /// <param name="uri"></param>
        public void DownLoadFile(Uri uri,string fileName)
        {
            //Create a stream for the file
            Stream stream = null;

            //This controls how many bytes to read at a time and send to the client
            int bytesToRead = ;

            // Buffer to read bytes in chunk size specified above
            byte[] buffer = new Byte[bytesToRead];

            // The number of bytes read
            try
            {
                long fileSize = FTPHelper.GetFileSize(uri);
                //Create a WebRequest to get the file
                FtpWebRequest fileReq = (FtpWebRequest)FtpWebRequest.Create(uri);

                //Create a response for this request
                FtpWebResponse fileResp = (FtpWebResponse)fileReq.GetResponse();

                //Get the Stream returned from the response
                stream = fileResp.GetResponseStream();

                // prepare the response to the client. resp is the client Response
                var resp = HttpContext.Response;

                //Indicate the type of data being sent
                resp.ContentType = "application/octet-stream";

                //Name the file
                resp.AddHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
                resp.AddHeader("Content-Length", fileSize.ToString());

                int length;
                do
                {
                    // Verify that the client is connected.
                    if (resp.IsClientConnected)
                    {
                        // Read data into the buffer.
                        length = stream.Read(buffer, , bytesToRead);

                        // and write it out to the response's output stream
                        resp.OutputStream.Write(buffer, , length);

                        // Flush the data
                        resp.Flush();

                        //Clear the buffer
                        buffer = new Byte[bytesToRead];
                    }
                    else
                    {
                        // cancel the download if client has disconnected
                        length = -;
                    }
                } while (length > ); //Repeat until no data is read
            }
            finally
            {
                if (stream != null)
                {
                    //Close the input stream
                    stream.Close();
                }
            }
        }