在浏览器中从FTP下载文件

 1     public static class FTPHelper

 2     {

 3         /// <summary>

 4         /// 得到特定FTP目录的文件列表

 5         /// </summary>

 6         /// <param name="uri">ftp://{username}:{password}@ftp.baidu.com/{folderName}</param>

 7         public static List<String> ListFiles(Uri serverUri)

 8         {

 9             // The serverUri parameter should start with the ftp:// scheme.

10             if (serverUri.Scheme != Uri.UriSchemeFtp)

11             {

12                 throw new ArgumentException("uri must be ftp scheme");

13             }

14 

15             FtpWebRequest ftpRequest = null;

16             StreamReader reader = null;

17             try

18             {

19                 // Get the object used to communicate with the server.

20                 ftpRequest = (FtpWebRequest)FtpWebRequest.Create(serverUri);

21 

22                 ftpRequest.Method = WebRequestMethods.Ftp.ListDirectory;

23 

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

25 

26                 //read data.

27                 List<String> fileNames = new List<String>();

28                 string line = reader.ReadLine();

29                 while (line != null)

30                 {

31 

32                     fileNames.Add(line);

33                     line = reader.ReadLine();

34                 }

35 

36                 return fileNames;

37 

38             }

39             catch(Exception ex)

40             {

41                 throw ex;

42             }

43             finally

44             { 

45               if(reader != null)

46               {

47                   reader.Close();

48               }

49               if (ftpRequest != null)

50               {

51                   ftpRequest.Abort();

52               }

53             }

54         }

55 

56         /// <summary>

57         /// 得到特定文件的大小

58         /// </summary>

59         /// <param name="uri">ftp://{username}:{password}@ftp.baidu.com/{fileName}</param>

60         public static long GetFileSize(Uri serverUri)

61         {

62             // The serverUri parameter should start with the ftp:// scheme.

63             if (serverUri.Scheme != Uri.UriSchemeFtp)

64             {

65                 throw new ArgumentException("uri must be ftp scheme");

66             }

67 

68             FtpWebRequest ftpRequest = null;

69             StreamReader reader = null;

70             try

71             {

72                 // Get the object used to communicate with the server.

73                 ftpRequest = (FtpWebRequest)FtpWebRequest.Create(serverUri);

74 

75                 ftpRequest.Method = WebRequestMethods.Ftp.GetFileSize;

76 

77                 return ftpRequest.GetResponse().ContentLength;

78             }

79             catch (Exception ex)

80             {

81                 throw ex;

82             }

83             finally

84             {

85                 if (reader != null)

86                 {

87                     reader.Close();

88                 }

89                 if (ftpRequest != null)

90                 {

91                     ftpRequest.Abort();

92                 }

93             }

94         }

95     }

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 = 10000;



            // 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, 0, bytesToRead);



                        // and write it out to the response's output stream

                        resp.OutputStream.Write(buffer, 0, length);



                        // Flush the data

                        resp.Flush();



                        //Clear the buffer

                        buffer = new Byte[bytesToRead];

                    }

                    else

                    {

                        // cancel the download if client has disconnected

                        length = -1;

                    }

                } while (length > 0); //Repeat until no data is read

            }

            finally

            {

                if (stream != null)

                {

                    //Close the input stream

                    stream.Close();

                }

            }

        }