com.cyberway.issue.net.ClientFTP.java Source code

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Here is the source code for com.cyberway.issue.net.ClientFTP.java

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/* ClientFTP.java
 *
 * $Id: ClientFTP.java 4573 2006-08-31 22:31:23Z paul_jack $
 *
 * Created on Jun 5, 2003
 *
 * Copyright (C) 2003 Internet Archive.
 *
 * This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 * Heritrix is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * any later version.
 *
 * Heritrix is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser Public License
 * along with Heritrix; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.cyberway.issue.net;

import java.io.IOException;
import java.net.Socket;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;

/**
 * Client for FTP operations.  This class is necessary only because the
 * {@link #_openDataConnection_(int, String)} method is protected in 
 * the superclass, and we need to call it directly to handle directory
 * listings.  (The code that provides directory listings in the 
 * superclass doesn't scale:  It reads the entire directory into
 * an in-memory list).
 * 
 * <p>Additionally, "strict" methods are provided for the other operations
 * we use.  Maddeningly, the superclass never raises exceptions.  If an 
 * FTP operation fails, then the superclass methods generally return false.
 * A developer then needs to check the {@link FTP#getReplyCode()}
 * method to see what actually went wrong.  The "strict" methods provided
 * by this class invoke the superclass method, check if the success flag
 * is false, and then raise an {@link FTPException} with the value of
 * {@link FTP#getReplyCode()}.
 *
 * @author pjack
 */
public class ClientFTP extends FTPClient {

    /**
     * Constructs a new <code>ClientFTP</code>.
     */
    public ClientFTP() {
    }

    /**
     * Connects to the FTP server at the given host and port.
     * 
     * @param host    the host of the FTP server to connect to
     * @param port    the port the FTP server listens on
     * @throws IOException  if the connection cannot be made due to IO error
     * @throws FTPException  if the server refuses the connection
     */
    public void connectStrict(String host, int port) throws IOException {
        this.connect(host, port);
        int reply = this.getReplyCode();
        if (!FTPReply.isPositiveCompletion(reply)) {
            throw new FTPException(reply);
        }
    }

    /**
     * Login to the FTP server with the given username and password.
     * 
     * @param user   the username to login under
     * @param pass   the password to use
     * @throws IOException   if a network error occurs
     * @throws FTPException  if the login is rejected by the server
     * @throws org.apache.commons.net.ftp.FTPConnectionClosedException   
     *   if the FTP server prematurely closes the connection (for 
     *   instance, if the client was idle for too long)
     */
    public void loginStrict(String user, String pass) throws IOException {
        boolean r = this.login(user, pass);
        if (!r) {
            throw new FTPException(this.getReplyCode());
        }
    }

    /**
     * Tells the FTP server to send binary files.
     *
     * @throws IOException   if a network error occurs
     * @throws FTPException  if the server rejects the command
     * @throws org.apache.commons.net.ftp.FTPConnectionClosedException   
     *   if the FTP server prematurely closes the connection (for 
     *   instance, if the client was idle for too long)
     */
    public void setBinary() throws IOException {
        boolean r = super.setFileType(BINARY_FILE_TYPE);
        if (!r) {
            throw new FTPException(getReplyCode());
        }
    }

    /**
     * Opens a data connection. 
     * 
     * @param command  the data command (eg, RETR or LIST)
     * @param path     the path of the file to retrieve
     * @return  the socket to read data from
     * @throws  IOException  if a network error occurs
     * @throws  FTPException  if a protocol error occurs
     */
    public Socket openDataConnection(int command, String path) throws IOException {
        Socket socket = _openDataConnection_(command, path);
        if (socket == null) {
            throw new FTPException(this.getReplyCode());
        }
        return socket;
    }

}