(转)重写common-net-ftp以适应内网Passive模式
转自http://www.diybl.com/course/3_program/java/javajs/20100719/453294.html
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需要重写几个地方
i. org.apache.commons.net.SocketClient

/** 用来自定义 Passive 模式的 Host */protected String _set_passive_host = "127.0.0.1";

    /**     * Opens a Socket connected to a remote host at the specified port and     * originating from the current host at a system assigned port.     * Before returning, {@link #_connectAction_  _connectAction_() }     * is called to perform connection initialization actions.     * <p>     * @param hostname  The name of the remote host.     * @param port  The port to connect to on the remote host.     * @exception SocketException If the socket timeout could not be set.     * @exception IOException If the socket could not be opened.  In most     *  cases you will only want to catch IOException since SocketException is     *  derived from it.     * @exception UnknownHostException If the hostname cannot be resolved.     */    public void connect(String hostname, int port)    throws SocketException, IOException    {        // 将连接的hostname赋给_set_passive_host        _set_passive_host = InetAddress.getByName(hostname).getHostAddress();        _socket_= _socketFactory_.createSocket();        _socket_.connect(new InetSocketAddress(hostname, port), connectTimeout);                _connectAction_();    }

ii. org.apache.commons.net.ftp.FTPClient

    private void __parsePassiveModeReply(String reply)    throws MalformedServerReplyException    {        java.util.regex.Matcher m = __parms_pat.matcher(reply);        if (!m.find()) {            throw new MalformedServerReplyException(                "Could not parse passive host information.\nServer Reply: " + reply);        }        reply = m.group();        String parts[] = m.group().split(",");                //__passiveHost = parts[0] + '.' + parts[1] + '.' + parts[2] + '.' + parts[3];        // 此处将_set_passive_host赋给__passiveHost        __passiveHost = _set_passive_host;        System.out.println(">----------->> Real Host IP is : "+__passiveHost);        try        {            int oct1 = Integer.parseInt(parts[4]);            int oct2 = Integer.parseInt(parts[5]);            __passivePort = (oct1 << 8) | oct2;        }        catch (NumberFormatException e)        {            throw new MalformedServerReplyException(                "Could not parse passive host information.\nServer Reply: " + reply);        }    }