org.apache.commons.net.ftp.FTPClient listFiles() 的问题 [英] Issue with org.apache.commons.net.ftp.FTPClient listFiles()

问题描述

org.apache.commons.net.ftp.FTPClient 的 listFiles() 方法在 127.0.0.1 上的 Filezilla 服务器上运行良好，但返回 null在belnet.be等公共FTP服务器的根目录下.

The listFiles() method of org.apache.commons.net.ftp.FTPClient works fine with Filezilla server on 127.0.0.1 but returns null on the root directory of public FTP servers such as belnet.be.

下面的链接上有一个相同的问题，但 enterRemotePassiveMode() 似乎没有帮助.Apache Commons FTPClient.listFiles

There is an identical question on the link below but enterRemotePassiveMode() doesn't seem to help. Apache Commons FTPClient.listFiles

会不会是列表解析的问题?如果是这样，如何解决这个问题?

Could it be an issue with list parsing? If so, how can go about solving this?

这是一个目录缓存转储:

Here's a directory cache dump:

FileZilla 目录缓存转储

FileZilla Directory Cache Dump

转储 1 个缓存目录

Entry 1:
Path: /
Server: [e-mail]: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

这是我使用我制作的包装器的代码(在包装器内部测试产生相同的结果):

Here's my code using a wrapper I've made (testing inside the wrapper produces the same results):

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" );
    }
}

产生这个输出:

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

在包装器内部(尝试同时使用 listNames() 和 listFiles() ):

Inside the wrapper (attempted using both 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;
        }

对于FTPClient，处理如下:

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;
}

推荐答案

每个 FTP 服务器都有不同的文件列表布局(是的，它不是 FTP 标准的一部分，它很愚蠢)，因此您必须使用正确的 FTPFileEntryParser，通过手动指定，或允许 CommonsFTP 自动检测.

Each FTP server has a different file list layout (yes, it's not part of the FTP standard, it's dumb), and so you have to use the correct FTPFileEntryParser, either by specifying it manually, or allowing CommonsFTP to auto-detect it.

自动检测通常工作正常，但有时它不会，并且您必须明确指定它，例如

Auto-detection usually works fine, but sometimes it doesn't, and you have to specify it explicitly, e.g.

FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);

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

这将预期的 FTP 服务器类型明确设置为 UNIX.尝试各种类型，看看效果如何.我试图找出自己，但 ftp.belnet.be 拒绝我的联系 :(

This explicitly sets the expected FTP server type to UNIX. Try the various types, see how it goes. I tried finding out myself, but ftp.belnet.be is refusing my connections :(

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