QBluetoothAbstractSocket Class Reference
[QtBluetoothModule]

Detailed Description

The QBluetoothAbstractSocket class represents an abstract Bluetooth client socket.

QBluetoothAbstractSocket is a common base class used by all Bluetooth sockets. This class implements functionality common to all socket types.

Clients that need to interact with RFCOMM based services should use the QBluetoothRfcommSocket class. For interacting with L2CAP based services, use the QBluetoothL2CapSocket class. Headset and Handsfree profile implementations might need to use the QBluetoothScoSocket class.

At any time, the QBluetoothAbstractSocket has a state (returned by state()). Upon creation, the initial state is QBluetoothAbstractSocket::UnconnectedState.

After calling connect(), the socket enters the QBluetoothAbstractSocket::ConnectingState. If connection is established, the socket enters QBluetoothAbstractSocket::ConnectedState and emits connected().

If an error occurs at any time, the error() signal is emitted. Whenever the state changes, stateChanged() is emitted. For convenience, isValid() returns true if the socket is ready for reading and writing.

Read or write data to/from the socket by calling read() or write(), or use the convenience functions readLine() and readAll(). QBluetoothAbstractSocket also inherits getChar(), putChar(), and ungetChar() from QIODevice, which work on single bytes. For every chunk of data that has been written to the socket, the bytesWritten() signal is emitted.

The readyRead() signal is emitted every time a new chunk of data has arrived. bytesAvailable() then returns the number of bytes that are available for reading. Typically, you would connect the readyRead() signal to a slot and read all available data there. If you don't read all the data at once, the remaining data will still be available later, and any new incoming data will be appended to QBluetoothAbstractSocket's internal read buffer. To limit the size of the read buffer, call setReadBufferSize().

To close the socket, call disconnect(). Once disconnect() is called, QBluetoothAbstractSocket enters the QBluetoothAbstractSocket::ClosingState and emits the stateChanged() signal. After all pending data has been written to the socket, QBluetoothAbstractSocket actually closes the socket, enters the QBluetoothAbstractSocket::ClosedState, and emits disconnected(). If no data is pending when disconnect() is called, the connection is disconnected immediately. If you want to abort a connection immediately, discarding all pending data, call abort() instead.

QBluetoothAbstractSocket provides a set of functions that suspend the calling thread until certain signals are emitted. These functions can be used to implement blocking sockets:

• waitForConnected() blocks until a connection has been established.
• waitForReadyRead() blocks until new data is available for reading.
• waitForBytesWritten() blocks until one payload of data has been written to the socket.
• waitForDisconnected() blocks until the connection has closed.

See also QBluetoothRfcommSocket, QBluetoothL2CapSocket, QBluetoothScoSocket, and QBluetoothL2CapDatagramSocket.

Member Type Documentation

enum QBluetoothAbstractSocket::SocketError

Error that last occurred on the rfcomm socket.

enum QBluetoothAbstractSocket::SocketState

State of the rfcomm socket.

Member Function Documentation

QBluetoothAbstractSocket::~QBluetoothAbstractSocket ()

Deconstructs a QBluetoothAbstractSocket. If the socket is in any state other than UnconnectedState, the current connection is aborted.

void QBluetoothAbstractSocket::abort ()

Aborts the current connection and resets the socket. Unlike disconnect(), this function immediately closes the socket, clearing any pending data in the write buffer.

See also disconnect() and close().

qint64 QBluetoothAbstractSocket::bytesAvailable () const   [virtual]

Returns the number of bytes that are waiting to be read.

Reimplemented from QIODevice.

See also bytesToWrite() and read().

qint64 QBluetoothAbstractSocket::bytesToWrite () const   [virtual]

Returns the number of bytes which are pending to be written.

Reimplemented from QIODevice.

See also bytesAvailable() and write().

bool QBluetoothAbstractSocket::canReadLine () const   [virtual]

Returns true if a line of data can be read from the socket; otherwise returns false.

Reimplemented from QIODevice.

See also readLine().

void QBluetoothAbstractSocket::close ()   [virtual]

Closes the socket. Pending data will not be flushed first. The socket will be immediately closed.

Reimplemented from QIODevice.

See also abort() and disconnect().

void QBluetoothAbstractSocket::connected ()   [signal]

This signal is emitted once the connect() has been called and the rfcomm socket has been successfully connected.

See also connect() and disconnected().

bool QBluetoothAbstractSocket::disconnect ()   [virtual]

Attempts to close the socket. If there is pending data waiting to be written, the socket will enter ClosingState and wait until all data has been written. Eventually it will enter UnconnectedState and emit the disconnected() signal.

Returns true on successful completion of the request; otherwise returns false.

See also close().

void QBluetoothAbstractSocket::disconnected ()   [signal]

This signal is emitted when the socket has been disconnected.

See also connect(), disconnect(), and abort().

SocketError QBluetoothAbstractSocket::error () const

Returns the last error that has occurred.

See also state().

void QBluetoothAbstractSocket::error ( QBluetoothAbstractSocket::SocketError socketError )   [signal]

This is an overloaded member function, provided for convenience.

This signal is emitted after an error occurred. The socketError parameter describes the type of error that has occurred.

See also error() and errorString().

bool QBluetoothAbstractSocket::flush ()   [virtual]

This function writes as much as possible from the internal write buffer to the underlying network socket, without blocking. If any data was written, this function returns true; otherwise false is returned.

See also write() and waitForBytesWritten().

qint64 QBluetoothAbstractSocket::readBufferSize () const

Returns the size of the internal read buffer. This limits the amount of data that the client can receive before you call read() or readAll().

A read buffer size of 0 (the default) means that the buffer has no size limit, ensuring that no data is lost.

See also setReadBufferSize() and read().

void QBluetoothAbstractSocket::setReadBufferSize ( qint64 size )

Sets the capacity of QBluetoothAbstractSocket's internal read buffer to be size bytes. If size is 0 the buffer has unlimited capacity. This is the default.

See also readBufferSize().

bool QBluetoothAbstractSocket::setSocketDescriptor ( int socketDescriptor, QBluetoothAbstractSocket::SocketState state, QIODevice::OpenMode openMode = QIODevice::ReadWrite )

Initializes the QBluetoothAbstractSocket with the native descriptor socketDescriptor. The socket is put into the state and opened in openMode.

Returns true on successful completion of the request; otherwise returns false.

See also socketDescriptor().

int QBluetoothAbstractSocket::socketDescriptor () const

Returns the socket descriptor for the socket if the socket is currently active (e.g. not in UnconnectedState). Otherwise returns -1.

See also setSocketDescriptor() and state().

SocketState QBluetoothAbstractSocket::state () const

Returns the state of the socket.

See also error().

void QBluetoothAbstractSocket::stateChanged ( QBluetoothAbstractSocket::SocketState socketState )   [signal]

This signal is emitted when the state of the socket has changed. The socketState parameter holds the new state.

See also state().

bool QBluetoothAbstractSocket::waitForConnected ( int msecs = 30000 )

Waits until the socket is connected, up to msecs milliseconds. If the connection has been established, this function returns true; otherwise returns false. In the case where it returns false, you can call error() to determine the cause of the error.

This is a blocking function call. Its use is not advised in a single-threaded GUI application, since the whole application will stop responding until the function returns. waitForNewConnected() is mostly useful when there is no event loop available.

See also connect() and connected().

bool QBluetoothAbstractSocket::waitForDisconnected ( int msecs = 30000 )

Waits until the socket is disconnected, up to msecs milliseconds. If the connection has been terminated, this function returns true; otherwise returns false. In the case where it returns false, you can call error() to determine the cause of the error.

This is a blocking function call. Its use is not advised in a single-threaded GUI application, since the whole application will stop responding until the function returns. waitForDisconnected() is mostly useful when there is no event loop available.

See also disconnect(), close(), and disconnected().