QFtp *ftp = new QFtp(parent);
ftp->connectToHost("ftp.qt.nokia.com");
ftp->login();

ftp->connectToHost("ftp.qt.nokia.com");   // id == 1
ftp->login();                             // id == 2
ftp->cd("qt");                            // id == 3
ftp->get("INSTALL");                      // id == 4
ftp->close();                             // id == 5

start(1)
stateChanged(HostLookup)
stateChanged(Connecting)
stateChanged(Connected)
finished(1, false)

start(2)
stateChanged(LoggedIn)
finished(2, false)

start(3)
finished(3, false)

start(4)
dataTransferProgress(0, 3798)
dataTransferProgress(2896, 3798)
readyRead()
dataTransferProgress(3798, 3798)
readyRead()
finished(4, false)

start(5)
stateChanged(Closing)
stateChanged(Unconnected)
finished(5, false)

done(false)

start(1)
stateChanged(HostLookup)
stateChanged(Connecting)
stateChanged(Connected)
finished(1, false)

start(2)
finished(2, true)

done(true)

Member Function Documentation

QFtp::QFtp(QObject * parent = 0)

Constructs a QFtp object with the given parent.

[virtual] QFtp::~QFtp()

Destructor.

[slot] void QFtp::abort()

Aborts the current command and deletes all scheduled commands.

If there is an unfinished command (i.e. a command for which the commandStarted() signal has been emitted, but for which the commandFinished() signal has not been emitted), this function sends an ABORT command to the server. When the server replies that the command is aborted, the commandFinished() signal with the error argument set to true is emitted for the command. Due to timing issues, it is possible that the command had already finished before the abort request reached the server, in which case, the commandFinished() signal is emitted with the error argument set to false.

For all other commands that are affected by the abort(), no signals are emitted.

If you don't start further FTP commands directly after the abort(), there won't be any scheduled commands and the done() signal is emitted.

Warning: Some FTP servers, for example the BSD FTP daemon (version 0.3), wrongly return a positive reply even when an abort has occurred. For these servers the commandFinished() signal has its error flag set to false, even though the command did not complete successfully.

See also clearPendingCommands().

qint64 QFtp::bytesAvailable() const

Returns the number of bytes that can be read from the data socket at the moment.

See also get(), readyRead(), read(), and readAll().

int QFtp::cd(const QString & dir)

Changes the working directory of the server to dir.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

void QFtp::clearPendingCommands()

Deletes all pending commands from the list of scheduled commands. This does not affect the command that is being executed. If you want to stop this as well, use abort().

See also hasPendingCommands() and abort().

int QFtp::close()

Closes the connection to the FTP server.

The stateChanged() signal is emitted when the state of the connecting process changes, e.g. to Closing, then Unconnected.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also stateChanged(), commandStarted(), and commandFinished().

[signal] void QFtp::commandFinished(int id, bool error)

This signal is emitted when processing the command identified by id has finished. error is true if an error occurred during the processing; otherwise error is false.

See also commandStarted(), done(), error(), and errorString().

[signal] void QFtp::commandStarted(int id)

This signal is emitted when processing the command identified by id starts.

See also commandFinished() and done().

int QFtp::connectToHost(const QString & host, quint16 port = 21)

Connects to the FTP server host using port port.

The stateChanged() signal is emitted when the state of the connecting process changes, e.g. to HostLookup, then Connecting, then Connected.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also stateChanged(), commandStarted(), and commandFinished().

Command QFtp::currentCommand() const

Returns the command type of the FTP command being executed or None if there is no command being executed.

See also currentId().

QIODevice * QFtp::currentDevice() const

Returns the QIODevice pointer that is used by the FTP command to read data from or store data to. If there is no current FTP command being executed or if the command does not use an IO device, this function returns 0.

This function can be used to delete the QIODevice in the slot connected to the commandFinished() signal.

See also get() and put().

int QFtp::currentId() const

Returns the identifier of the FTP command that is being executed or 0 if there is no command being executed.

See also currentCommand().

[signal] void QFtp::dataTransferProgress(qint64 done, qint64 total)

This signal is emitted in response to a get() or put() request to indicate the current progress of the download or upload.

done is the amount of data that has already been transferred and total is the total amount of data to be read or written. It is possible that the QFtp class is not able to determine the total amount of data that should be transferred, in which case total is 0. (If you connect this signal to a QProgressBar, the progress bar shows a busy indicator if the total is 0).

Warning: done and total are not necessarily the size in bytes, since for large files these values might need to be "scaled" to avoid overflow.

See also get(), put(), and QProgressBar.

[signal] void QFtp::done(bool error)

This signal is emitted when the last pending command has finished; (it is emitted after the last command's commandFinished() signal). error is true if an error occurred during the processing; otherwise error is false.

See also commandFinished(), error(), and errorString().

Error QFtp::error() const

Returns the last error that occurred. This is useful to find out what went wrong when receiving a commandFinished() or a done() signal with the error argument set to true.

If you start a new command, the error status is reset to NoError.

QString QFtp::errorString() const

Returns a human-readable description of the last error that occurred. This is useful for presenting a error message to the user when receiving a commandFinished() or a done() signal with the error argument set to true.

The error string is often (but not always) the reply from the server, so it is not always possible to translate the string. If the message comes from Qt, the string has already passed through tr().

int QFtp::get(const QString & file, QIODevice * dev = 0, TransferType type = Binary)

Downloads the file file from the server.

If dev is 0, then the readyRead() signal is emitted when there is data available to read. You can then read the data with the read() or readAll() functions.

If dev is not 0, the data is written directly to the device dev. Make sure that the dev pointer is valid for the duration of the operation (it is safe to delete it when the commandFinished() signal is emitted). In this case the readyRead() signal is not emitted and you cannot read data with the read() or readAll() functions.

If you don't read the data immediately it becomes available, i.e. when the readyRead() signal is emitted, it is still available until the next command is started.

For example, if you want to present the data to the user as soon as there is something available, connect to the readyRead() signal and read the data immediately. On the other hand, if you only want to work with the complete data, you can connect to the commandFinished() signal and read the data when the get() command is finished.

The data is transferred as Binary or Ascii depending on the value of type.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

commandFinished()

See also readyRead(), dataTransferProgress(), and commandStarted().

bool QFtp::hasPendingCommands() const

Returns true if there are any commands scheduled that have not yet been executed; otherwise returns false.

The command that is being executed is not considered as a scheduled command.

See also clearPendingCommands(), currentId(), and currentCommand().

int QFtp::list(const QString & dir = QString())

Lists the contents of directory dir on the FTP server. If dir is empty, it lists the contents of the current directory.

The listInfo() signal is emitted for each directory entry found.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also listInfo(), commandStarted(), and commandFinished().

[signal] void QFtp::listInfo(const QUrlInfo & i)

This signal is emitted for each directory entry the list() command finds. The details of the entry are stored in i.

See also list().

int QFtp::login(const QString & user = QString(), const QString & password = QString())

Logs in to the FTP server with the username user and the password password.

The stateChanged() signal is emitted when the state of the connecting process changes, e.g. to LoggedIn.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

int QFtp::mkdir(const QString & dir)

Creates a directory called dir on the server.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

int QFtp::put(QIODevice * dev, const QString & file, TransferType type = Binary)

Reads the data from the IO device dev, and writes it to the file called file on the server. The data is read in chunks from the IO device, so this overload allows you to transmit large amounts of data without the need to read all the data into memory at once.

The data is transferred as Binary or Ascii depending on the value of type.

Make sure that the dev pointer is valid for the duration of the operation (it is safe to delete it when the commandFinished() is emitted).

int QFtp::put(const QByteArray & data, const QString & file, TransferType type = Binary)

This is an overloaded function.

Writes a copy of the given data to the file called file on the server. The progress of the upload is reported by the dataTransferProgress() signal.

The data is transferred as Binary or Ascii depending on the value of type.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

Since this function takes a copy of the data, you can discard your own copy when this function returns.

See also dataTransferProgress(), commandStarted(), and commandFinished().

int QFtp::rawCommand(const QString & command)

Sends the raw FTP command command to the FTP server. This is useful for low-level FTP access. If the operation you wish to perform has an equivalent QFtp function, we recommend using the function instead of raw FTP commands since the functions are easier and safer.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also rawCommandReply(), commandStarted(), and commandFinished().

[signal] void QFtp::rawCommandReply(int replyCode, const QString & detail)

This signal is emitted in response to the rawCommand() function. replyCode is the 3 digit reply code and detail is the text that follows the reply code.

See also rawCommand().

qint64 QFtp::read(char * data, qint64 maxlen)

Reads maxlen bytes from the data socket into data and returns the number of bytes read. Returns -1 if an error occurred.

See also get(), readyRead(), bytesAvailable(), and readAll().

QByteArray QFtp::readAll()

Reads all the bytes available from the data socket and returns them.

See also get(), readyRead(), bytesAvailable(), and read().

[signal] void QFtp::readyRead()

This signal is emitted in response to a get() command when there is new data to read.

If you specify a device as the second argument in the get() command, this signal is not emitted; instead the data is written directly to the device.

You can read the data with the readAll() or read() functions.

This signal is useful if you want to process the data in chunks as soon as it becomes available. If you are only interested in the complete data, just connect to the commandFinished() signal and read the data then instead.

See also get(), read(), readAll(), and bytesAvailable().

int QFtp::remove(const QString & file)

Deletes the file called file from the server.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

int QFtp::rename(const QString & oldname, const QString & newname)

Renames the file called oldname to newname on the server.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

int QFtp::rmdir(const QString & dir)

Removes the directory called dir from the server.

The function does not block and returns immediately. The command is scheduled, and its execution is performed asynchronously. The function returns a unique identifier which is passed by commandStarted() and commandFinished().

When the command is started the commandStarted() signal is emitted. When it is finished the commandFinished() signal is emitted.

See also commandStarted() and commandFinished().

int QFtp::setProxy(const QString & host, quint16 port)

Enables use of the FTP proxy on host host and port port. Calling this function with host empty disables proxying.

QFtp does not support FTP-over-HTTP proxy servers. Use QNetworkAccessManager for this.

int QFtp::setTransferMode(TransferMode mode)

Sets the current FTP transfer mode to mode. The default is QFtp::Passive.

See also QFtp::TransferMode.

State QFtp::state() const

Returns the current state of the object. When the state changes, the stateChanged() signal is emitted.

See also State and stateChanged().

[signal] void QFtp::stateChanged(int state)

This signal is emitted when the state of the connection changes. The argument state is the new state of the connection; it is one of the State values.

It is usually emitted in response to a connectToHost() or close() command, but it can also be emitted "spontaneously", e.g. when the server closes the connection unexpectedly.

See also connectToHost(), close(), state(), and State.