java – org. apache. commons. net. ftp. Problem with ftpclient listfiles()

org. apache. commons. net. ftp. The listfiles() method of ftpclient is applicable to 127.0 0.1, but returns null under the root directory of a public FTP server (such as belnet. Be)

There is the same problem on the link below, but enterremotepassivemode() doesn't seem to help Apache Commons FTPClient. listFiles

Could this be a problem with list parsing? If so, how can we solve this problem?

Edit: This is a directory cache dump:

FileZilla directory cache dump

Dump 1 cache directory

Entry 1:
Path: /
Server: anonymous@ftp.belnet.be:21,type: 4096
Directory contains 7 items:
  lrw-r--r-- ftp ftp      D          28      2009-06-17   debian
  lrw-r--r-- ftp ftp      D          31      2009-06-17   debian-cd
  -rw-r--r-- ftp ftp                  0 2010-03-04 13:30  keepalive.txt
  drwxr-xr-x ftp ftp      D        4096 2010-02-18 14:22  mirror
  lrw-r--r-- ftp ftp      D           6      2009-06-17   mirrors
  drwxr-xr-x ftp ftp      D        4096      2009-06-23   packages
  lrw-r--r-- ftp ftp      D           1      2009-06-17   pub

This is the code that I use the wrapper I made (the test in the wrapper produces the same result):

public static void main(String[] args) {        
    FTPUtils ftpUtils = new FTPUtils();
    String ftpURL = "ftp.belnet.be";
    Connection connection = ftpUtils.getFTPClientManager().getConnection( ftpURL );

    if( connection == null ){
        System.out.println( "Could not connect" );
        return; 
    }

    FTPClientManager manager = connection.getFptClientManager();
    FTPClient client = manager.getClient();

    try {
        client.enterRemotePassiveMode();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    if( connection != null ){
        System.out.println( "Connected to FTP" );
        connection.login("Anonymous","Anonymous");
        if( connection.isLoggedIn() ){
            System.out.println( "Login successful" );
            LoggedInManager loggedin = connection.getLoggedInManager(); 
            System.out.println( loggedin );
            String[] fileList = loggedin.getFileList();

            System.out.println( loggedin.getWorkingDirectory() );

            if( fileList == null || fileList.length == 0 )
                System.out.println( "No files found" );
            else{
                for (String name : fileList ) {
                    System.out.println( name );
                }
            }

            connection.disconnect();

            if( connection.isDisconnected() )
                System.out.println( "Disconnection successful" );
            else
                System.out.println( "Error disconnecting" );
        }else{
            System.out.println( "Unable to login" );
        }
    } else {
        System.out.println( "Could not connect" );
    }
}

Generate this output:

Connected to FTP
Login succesful
utils.ftp.FTPClientManager$Connection$LoggedInManager@156ee8e
null
No files found
Disconnection successful

Inside the wrapper (try listnames() and listfiles()):

public String[] getFileList() {
            String[] fileList = null;
            FTPFile[] ftpFiles = null;

            try {
                ftpFiles = client.listFiles();
                //fileList = client.listNames();
                //System.out.println( client.listNames() );
            } catch (IOException e) {
                return null;
            }

            fileList = new String[ ftpFiles.length ];

            for( int i = 0; i < ftpFiles.length; i++ ){
                fileList[ i ] = ftpFiles[ i ].getName();
            }

            return fileList;
        }

As for ftpclient, it is handled as follows:

public class FTPUtils {

private FTPClientManager clientManager;

public FTPClientManager getFTPClientManager(){
    clientManager = new FTPClientManager();
    clientManager.setClient( new FTPClient() );

    return clientManager;
}

Solution

Each FTP server has a different file list layout (yes, it's not part of the FTP standard, it's stupid), so you must use the correct ftpfileentryparser, specify it manually, or allow commonsftp to detect it automatically

Automatic detection usually works, but sometimes it doesn't. You must specify it explicitly, such as

FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);

FTPClient client = FTPClient();
client.configure(conf);

This explicitly sets the expected FTP server type to UNIX Try various types and see how it works I tried to find myself, but FTP belnet. Be declined my contact:（