FTP Connection Timed out 421 : parser error

问题:

The question has beed edited. I am trying to list all the files in a FTP directory - and though the code works fine when run in a normal Netbeans project, when using the same code in a Maven project its results in a connection timed out 421 . How can I get rid of this?

Code:

FTPClient ftpClient = new FTPClient();
ftpClient.connect(host, 21);
ftpClient.login(user, pass);
ftpClient.enterLocalPassiveMode();
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);
ftpClient.configure(conf);
inputStream = FTPUtil.downloadSingleFile(ftpClient, filePath);
ftpClient.list();                         // It works
ftpClient.listNames("/");                 // It works
ftpClient.changeWorkingDirectory("/");    // It works
FTPFile[] files = ftpClient.listFiles("/");// It hangs and stops 421 connection timed out

The FileZilla log is:-

    (000370)04-04-2013 16:04:32 - (not logged in) (127.0.0.1)> Connected, sending welcome message...
    (000370)04-04-2013 16:04:32 - (not logged in) (127.0.0.1)> 220 ftp connection started...
    (000370)04-04-2013 16:04:32 - (not logged in) (127.0.0.1)> USER raja
    (000370)04-04-2013 16:04:32 - (not logged in) (127.0.0.1)> 331 Password required for raja
    (000370)04-04-2013 16:04:32 - (not logged in) (127.0.0.1)> PASS ****
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> 230 Logged on
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> TYPE I
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> 200 Type set to I
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> PASV
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> 227 Entering Passive Mode (127,0,0,1,237,187)
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> SYST
    (000370)04-04-2013 16:04:32 - raja (127.0.0.1)> 215 UNIX emulated by FileZilla
    (000366)04-04-2013 16:04:33 - raja (127.0.0.1)> 421 Connection timed out.

The Client side exceptions are:-

回答1:

There is a serious issue in the apache-commons 1.4.1 in handling the parsing exception when the FTP server returns null against SYST command . I tried using version 3.2 and the issue got resolved.