Setting connect timeout for FtpClient

Question

When using ftpClient.connect with an existing host who has no ftp service active, timeout occurs only after 5 minutes, which is much too long.

I tried setting diverse timeouts (setDefaultTimeout, setDataTimeout) which did not change anything.

FtpClient inherits from SocketClient which has a setConnectTimeout method, but when I use this I get a java.lang.NoSuchMethodError: org/apache/commons/net/ftp/FTPClient.setConnectTimeout when running it. This seems to be because of some J2SW 1.2 compatibility, as described in Commons-net FAQ:

Q: How can I set a connection timeout? http://wiki.apache.org/commons/Net/FrequentlyAskedQuestions

They suggest to implement an own SocketFactory creating objects from an extended Socket class using a specific timeout. However, when trying to use ftpClient.setSocketFactory I also get a java.lang.NoSuchMethodError.

Any help how I can reduce the connect timeout?

Answer 1

    FTPClient ftp = new FTPClient();

    ftp.setDefaultTimeout();
    ftp.setDataTimeout();
    ftp.setConnectTimeout();
    ftp.setSoTimeout();
    ftp.setControlKeepAliveTimeout();
    ftp.setControlKeepAliveReplyTimeout();

From Apache docs:

   /**
     * Set the default timeout in milliseconds to use when opening a socket.
     * This value is only used previous to a call to
     * {@link #connect connect()}
     * and should not be confused with {@link #setSoTimeout setSoTimeout()}
     * which operates on an the currently opened socket.  _timeout_ contains
     * the new timeout value.
     * <p>
     * @param timeout  The timeout in milliseconds to use for the socket
     *                 connection.
     */
    void setDefaultTimeout(int timeout);


    /**
     * Sets the timeout in milliseconds to use when reading from the
     * data connection.  This timeout will be set immediately after
     * opening the data connection, provided that the value is &ge; 0.
     * <p>
     * <b>Note:</b> the timeout will also be applied when calling accept()
     * whilst establishing an active local data connection.
     * @param  timeout The default timeout in milliseconds that is used when
     *        opening a data connection socket. The value 0 means an infinite timeout.
     */
    void setDataTimeout(int timeout)
    /**
     * Sets the connection timeout in milliseconds, which will be passed to the {@link java.net.Socket} object's
     * connect() method.
     * @param connectTimeout The connection timeout to use (in ms)
     * @since 2.0
     */
    void setConnectTimeout(int connectTimeout);
    /**
     * Set the timeout in milliseconds of a currently open connection.
     * Only call this method after a connection has been opened
     * by {@link #connect connect()}.
     * <p>
     * To set the initial timeout, use {@link #setDefaultTimeout(int)} instead.
     *
     * @param timeout  The timeout in milliseconds to use for the currently
     *                 open socket connection.
     * @exception SocketException If the operation fails.
     * @throws NullPointerException if the socket is not currently open
     */
    void setSoTimeout(int timeout) throws SocketException;
    /**
     * Set the time to wait between sending control connection keepalive messages
     * when processing file upload or download.
     *
     * @param controlIdle the wait (in secs) between keepalive messages. Zero (or less) disables.
     * @since 3.0
     * @see #setControlKeepAliveReplyTimeout(int)
     */
    void setControlKeepAliveTimeout(long controlIdle);

    /**
     * Set how long to wait for control keep-alive message replies.
     *
     * @param timeout number of milliseconds to wait (defaults to 1000)
     * @since 3.0
     * @see #setControlKeepAliveTimeout(long)
     */
    void setControlKeepAliveReplyTimeout(int timeout)