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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.core.QIODevice
com.trolltech.qt.network.QAbstractSocket
public class QAbstractSocket
The QAbstractSocket class provides the base functionality common to all socket types.
QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. If you need a socket, you have two options:
TCP (Transmission Control Protocol) is a reliable, stream-oriented, connection-oriented transport protocol. UDP (User Datagram Protocol) is an unreliable, datagram-oriented, connectionless protocol. In practice, this means that TCP is better suited for continuous transmission of data, whereas the more lightweight UDP can be used when reliability isn't important.
QAbstractSocket's API unifies most of the differences between the two protocols. For example, although UDP is connectionless, connectToHost() establishes a virtual connection for UDP sockets, enabling you to use QAbstractSocket in more or less the same way regardless of the underlying protocol. Internally, QAbstractSocket remembers the address and port passed to connectToHost(), and functions like read and write use these values.
At any time, QAbstractSocket has a state (returned by state). The initial state is UnconnectedState. After calling connectToHost(), the socket first enters HostLookupState. If the host is found, QAbstractSocket enters ConnectingState and emits the hostFound signal. When the connection has been established, it enters ConnectedState and emits connected. If an error occurs at any stage, error is emitted. Whenever the state changes, stateChanged is emitted. For convenience, isValid returns true if the socket is ready for reading and writing, but note that the socket's state must be ConnectedState before reading and writing can occur.
Read or write data by calling read or write, or use the convenience functions readLine and readAll. QAbstractSocket 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 QAbstractSocket's internal read buffer. To limit the size of the read buffer, call setReadBufferSize.
To close the socket, call disconnectFromHost. QAbstractSocket enters QAbstractSocket::ClosingState, then emits closing(). After all pending data has been written to the socket, QAbstractSocket actually closes the socket, enters QAbstractSocket::ClosedState, and emits disconnected. If you want to abort a connection immediately, discarding all pending data, call abort instead. If the remote host closes the connection, QAbstractSocket will emit error(QAbstractSocket::RemoteHostClosedError), during which the socket state will still be ConnectedState, and then the disconnected signal will be emitted.
The port and address of the connected peer is fetched by calling peerPort() and peerAddress. peerName returns the host name of the peer, as passed to connectToHost(). localPort() and localAddress return the port and address of the local socket.
QAbstractSocket provides a set of functions that suspend the calling thread until certain signals are emitted. These functions can be used to implement blocking sockets:
We show an example:
int numRead = 0, numReadTotal = 0;
char buffer[50];
forever {
numRead = socket.read(buffer, 50);
// do whatever with array
numReadTotal += numRead;
if (numRead == 0 && !socket.waitForReadyRead())
break;
}
If waitForReadyRead() returns false, the connection has been closed or an error has occurred.
Programming with a blocking socket is radically different from programming with a non-blocking socket. A blocking socket doesn't require an event loop and typically leads to simpler code. However, in a GUI application, blocking sockets should only be used in non-GUI threads, to avoid freezing the user interface. See the network/fortuneclient and network/blockingfortuneclient examples for an overview of both approaches.
QAbstractSocket can be used with QTextStream and QDataStream's stream operators (operator<<() and operator>>()). There is one issue to be aware of, though: You must make sure that enough data is available before attempting to read it using operator>>().
Nested Class Summary | |
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static class |
QAbstractSocket.NetworkLayerProtocol
This enum describes the network layer protocol values used in Qt. |
static class |
QAbstractSocket.SocketError
This enum describes the socket errors that can occur. |
static class |
QAbstractSocket.SocketState
This enum describes the different states in which a socket can be. |
static class |
QAbstractSocket.SocketType
This enum describes the transport layer protocol. |
Nested classes/interfaces inherited from class com.trolltech.qt.core.QIODevice |
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QIODevice.OpenMode, QIODevice.OpenModeFlag |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
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QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Field Summary | |
---|---|
QSignalEmitter.Signal0 |
connected
This signal is emitted after connectToHost() has been called and a connection has been successfully established. |
QSignalEmitter.Signal0 |
disconnected
This signal is emitted when the socket has been disconnected. |
QSignalEmitter.Signal1<QAbstractSocket.SocketError> |
error
This signal is emitted after an error occurred. |
QSignalEmitter.Signal0 |
hostFound
This signal is emitted after connectToHost() has been called and the host lookup has succeeded. |
QSignalEmitter.Signal2<QNetworkProxy,QAuthenticator> |
proxyAuthenticationRequired
|
QSignalEmitter.Signal1<QAbstractSocket.SocketState> |
stateChanged
This signal is emitted whenever QAbstractSocket's state changes. |
Fields inherited from class com.trolltech.qt.core.QIODevice |
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aboutToClose, bytesWritten, readyRead |
Constructor Summary | |
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QAbstractSocket(QAbstractSocket.SocketType socketType,
QObject parent)
Creates a new abstract socket of type socketType. |
Method Summary | |
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void |
abort()
Aborts the current connection and resets the socket. |
boolean |
atEnd()
This function is reimplemented for internal reasons. |
long |
bytesAvailable()
Returns the number of incoming bytes that are waiting to be read. |
long |
bytesToWrite()
Returns the number of bytes that are waiting to be written. |
boolean |
canReadLine()
Returns true if a line of data can be read from the socket; otherwise returns false. |
void |
close()
Disconnects the socket's connection with the host. |
void |
connectToHost(QHostAddress host,
int port,
QIODevice.OpenMode mode)
Attempts to make a connection to address on port port with open mode mode. |
void |
connectToHost(java.lang.String host,
int port,
QIODevice.OpenMode mode)
Attempts to make a connection to host on the given port. |
protected void |
connectToHostImplementation(java.lang.String host,
int port,
QIODevice.OpenMode mode)
Contains the implementation of connectToHost(). |
void |
disconnectFromHost()
Attempts to close the socket. |
protected void |
disconnectFromHostImplementation()
Contains the implementation of disconnectFromHost. |
QAbstractSocket.SocketError |
error()
Returns the type of error that last occurred. |
boolean |
flush()
This function writes as much as possible from the internal write buffer to the underlying network socket, without blocking. |
static QAbstractSocket |
fromNativePointer(QNativePointer nativePointer)
This function returns the QAbstractSocket instance pointed to by nativePointer |
boolean |
isSequential()
This function is reimplemented for internal reasons. |
boolean |
isValid()
Returns true if the socket is valid and ready for use; otherwise returns false. |
QHostAddress |
localAddress()
Returns the host address of the local socket if available; otherwise returns QHostAddress::Null. |
int |
localPort()
Returns the host port number (in native byte order) of the local socket if available; otherwise returns 0. |
QHostAddress |
peerAddress()
Returns the address of the connected peer if the socket is in ConnectedState; otherwise returns QHostAddress::Null. |
java.lang.String |
peerName()
Returns the name of the peer as specified by connectToHost(), or an empty QString if connectToHost() has not been called. |
int |
peerPort()
Returns the port of the connected peer if the socket is in ConnectedState; otherwise returns 0. |
QNetworkProxy |
proxy()
Returns the network proxy for this socket. |
long |
readBufferSize()
Returns the size of the internal read buffer. |
protected int |
readData(byte[] data)
Equivalent to readData(data, ). |
protected int |
readLineData(byte[] data)
Equivalent to readLineData(data, ). |
protected void |
setLocalAddress(QHostAddress address)
Sets the address on the local side of a connection to address. |
protected void |
setLocalPort(int port)
Sets the local port of this QAbstractSocket to port. |
protected void |
setPeerAddress(QHostAddress address)
Sets the address of the remote side of the connection to address. |
protected void |
setPeerName(java.lang.String name)
Sets the host name of the remote peer to name. |
protected void |
setPeerPort(int port)
Sets the peer port of this QAbstractSocket to port. |
void |
setProxy(QNetworkProxy networkProxy)
Sets the explicit network proxy for this socket to networkProxy. |
void |
setReadBufferSize(long size)
Sets the size of QAbstractSocket's internal read buffer to be size bytes. |
boolean |
setSocketDescriptor(int socketDescriptor)
Equivalent to setSocketDescriptor(socketDescriptor, ConnectedState, ReadWrite). |
boolean |
setSocketDescriptor(int socketDescriptor,
QAbstractSocket.SocketState state)
Equivalent to setSocketDescriptor(socketDescriptor, state, ReadWrite). |
boolean |
setSocketDescriptor(int socketDescriptor,
QAbstractSocket.SocketState state,
QIODevice.OpenMode openMode)
Initializes QAbstractSocket with the native socket descriptor socketDescriptor. |
boolean |
setSocketDescriptor(int socketDescriptor,
QAbstractSocket.SocketState state,
QIODevice.OpenModeFlag... openMode)
Initializes QAbstractSocket with the native socket descriptor socketDescriptor. |
protected void |
setSocketError(QAbstractSocket.SocketError socketError)
Sets the type of error that last occurred to socketError. |
protected void |
setSocketState(QAbstractSocket.SocketState state)
Sets the state of the socket to state. |
int |
socketDescriptor()
Returns the native socket descriptor of the QAbstractSocket object if this is available; otherwise returns -1. |
QAbstractSocket.SocketType |
socketType()
Returns the socket type (TCP, UDP, or other). |
QAbstractSocket.SocketState |
state()
Returns the state of the socket. |
boolean |
waitForBytesWritten(int msecs)
This function is reimplemented for internal reasons. |
boolean |
waitForConnected()
Equivalent to waitForConnected(30000). |
boolean |
waitForConnected(int msecs)
Waits until the socket is connected, up to msecs milliseconds. |
boolean |
waitForDisconnected()
Equivalent to waitForDisconnected(30000). |
boolean |
waitForDisconnected(int msecs)
Waits until the socket has disconnected, up to msecs milliseconds. |
boolean |
waitForReadyRead(int msecs)
This function blocks until data is available for reading and the readyRead() signal has been emitted. |
protected int |
writeData(byte[] data)
Equivalent to writeData(data, ). |
Methods inherited from class com.trolltech.qt.core.QIODevice |
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errorString, getByte, isOpen, isReadable, isTextModeEnabled, isWritable, open, open, openMode, peek, peek, pos, putByte, read, read, readAll, readLine, readLine, readLine, reset, seek, setErrorString, setOpenMode, setOpenMode, setTextModeEnabled, size, ungetByte, write, write |
Methods inherited from class com.trolltech.qt.core.QObject |
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blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread, timerEvent |
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
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disconnect, disconnect, signalSender |
Methods inherited from class java.lang.Object |
---|
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Field Detail |
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public final QSignalEmitter.Signal0 connected
This signal is emitted after connectToHost() has been called and a connection has been successfully established.
public final QSignalEmitter.Signal0 disconnected
This signal is emitted when the socket has been disconnected.
public final QSignalEmitter.Signal1<QAbstractSocket.SocketError> error
This signal is emitted after an error occurred. The arg__1 parameter describes the type of error that occurred.
QAbstractSocket::SocketError is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE.
public final QSignalEmitter.Signal0 hostFound
This signal is emitted after connectToHost() has been called and the host lookup has succeeded.
public final QSignalEmitter.Signal1<QAbstractSocket.SocketState> stateChanged
This signal is emitted whenever QAbstractSocket's state changes. The arg__1 parameter is the new state.
QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE.
public QSignalEmitter.Signal2<QNetworkProxy,QAuthenticator> proxyAuthenticationRequired
Constructor Detail |
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public QAbstractSocket(QAbstractSocket.SocketType socketType, QObject parent)
Creates a new abstract socket of type socketType. The parent argument is passed to QObject's constructor.
Method Detail |
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public final void abort()
Aborts the current connection and resets the socket. Unlike disconnectFromHost, this function immediately closes the socket, clearing any pending data in the write buffer.
public final void disconnectFromHost()
Attempts to close the socket. If there is pending data waiting to be written, QAbstractSocket will enter ClosingState and wait until all data has been written. Eventually, it will enter UnconnectedState and emit the disconnected signal.
protected final void disconnectFromHostImplementation()
Contains the implementation of disconnectFromHost.
public final QAbstractSocket.SocketError error()
Returns the type of error that last occurred.
public final boolean flush()
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.
Call this function if you need QAbstractSocket to start sending buffered data immediately. The number of bytes successfully written depends on the operating system. In most cases, you do not need to call this function, because QAbstractSocket will start sending data automatically once control goes back to the event loop. In the absence of an event loop, call waitForBytesWritten instead.
public final boolean isValid()
Returns true if the socket is valid and ready for use; otherwise returns false.
Note: The socket's state must be ConnectedState before reading and writing can occur.
public final QHostAddress localAddress()
Returns the host address of the local socket if available; otherwise returns QHostAddress::Null.
This is normally the main IP address of the host, but can be QHostAddress::LocalHost (127.0.0.1) for connections to the local host.
public final QHostAddress peerAddress()
Returns the address of the connected peer if the socket is in ConnectedState; otherwise returns QHostAddress::Null.
public final java.lang.String peerName()
Returns the name of the peer as specified by connectToHost(), or an empty QString if connectToHost() has not been called.
public final QNetworkProxy proxy()
Returns the network proxy for this socket. By default QNetworkProxy::DefaultProxy is used.
public final long readBufferSize()
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.
protected final void setLocalAddress(QHostAddress address)
Sets the address on the local side of a connection to address.
You can call this function in a subclass of QAbstractSocket to change the return value of the localAddress function after a connection has been established. This feature is commonly used by proxy connections for virtual connection settings.
Note that this function does not bind the local address of the socket prior to a connection (e.g., QUdpSocket::bind()).
protected final void setPeerAddress(QHostAddress address)
Sets the address of the remote side of the connection to address.
You can call this function in a subclass of QAbstractSocket to change the return value of the peerAddress function after a connection has been established. This feature is commonly used by proxy connections for virtual connection settings.
protected final void setPeerName(java.lang.String name)
Sets the host name of the remote peer to name.
You can call this function in a subclass of QAbstractSocket to change the return value of the peerName function after a connection has been established. This feature is commonly used by proxy connections for virtual connection settings.
public final void setProxy(QNetworkProxy networkProxy)
Sets the explicit network proxy for this socket to networkProxy.
To disable the use of a proxy for this socket, use the QNetworkProxy::NoProxy proxy type:
socket->setProxy(QNetworkProxy::NoProxy);
public final void setReadBufferSize(long size)
Sets the size of QAbstractSocket's internal read buffer to be size bytes.
If the buffer size is limited to a certain size, QAbstractSocket won't buffer more than this size of data. Exceptionally, a buffer size of 0 means that the read buffer is unlimited and all incoming data is buffered. This is the default.
This option is useful if you only read the data at certain points in time (e.g., in a real-time streaming application) or if you want to protect your socket against receiving too much data, which may eventually cause your application to run out of memory.
Only QTcpSocket uses QAbstractSocket's internal buffer; QUdpSocket does not use any buffering at all, but rather relies on the implicit buffering provided by the operating system. Because of this, calling this function on QUdpSocket has no effect.
public final boolean setSocketDescriptor(int socketDescriptor, QAbstractSocket.SocketState state, QIODevice.OpenModeFlag... openMode)
Initializes QAbstractSocket with the native socket descriptor socketDescriptor. Returns true if socketDescriptor is accepted as a valid socket descriptor; otherwise returns false. The socket is opened in the mode specified by openMode, and enters the socket state specified by state.
Note: It is not possible to initialize two abstract sockets with the same native socket descriptor.
public final boolean setSocketDescriptor(int socketDescriptor, QAbstractSocket.SocketState state)
Equivalent to setSocketDescriptor(socketDescriptor, state, ReadWrite).
public final boolean setSocketDescriptor(int socketDescriptor)
Equivalent to setSocketDescriptor(socketDescriptor, ConnectedState, ReadWrite).
public final boolean setSocketDescriptor(int socketDescriptor, QAbstractSocket.SocketState state, QIODevice.OpenMode openMode)
Initializes QAbstractSocket with the native socket descriptor socketDescriptor. Returns true if socketDescriptor is accepted as a valid socket descriptor; otherwise returns false. The socket is opened in the mode specified by openMode, and enters the socket state specified by state.
Note: It is not possible to initialize two abstract sockets with the same native socket descriptor.
protected final void setSocketError(QAbstractSocket.SocketError socketError)
Sets the type of error that last occurred to socketError.
protected final void setSocketState(QAbstractSocket.SocketState state)
Sets the state of the socket to state.
public final int socketDescriptor()
Returns the native socket descriptor of the QAbstractSocket object if this is available; otherwise returns -1.
If the socket is using QNetworkProxy, the returned descriptor may not be usable with native socket functions.
The socket descriptor is not available when QAbstractSocket is in UnconnectedState.
public final QAbstractSocket.SocketType socketType()
Returns the socket type (TCP, UDP, or other).
public final QAbstractSocket.SocketState state()
Returns the state of the socket.
public final boolean waitForConnected()
Equivalent to waitForConnected(30000).
public final boolean waitForConnected(int msecs)
Waits until the socket is connected, up to msecs milliseconds. If the connection has been established, this function returns true; otherwise it returns false. In the case where it returns false, you can call error to determine the cause of the error.
The following example waits up to one second for a connection to be established:
socket->connectToHost("imap", 143); if (socket->waitForConnected(1000)) qDebug("Connected!");
If msecs is -1, this function will not time out.
Note: This function may wait slightly longer than msecs, depending on the time it takes to complete the host lookup.
public final boolean waitForDisconnected()
Equivalent to waitForDisconnected(30000).
public final boolean waitForDisconnected(int msecs)
Waits until the socket has disconnected, up to msecs milliseconds. If the connection has been disconnected, this function returns true; otherwise it returns false. In the case where it returns false, you can call error to determine the cause of the error.
The following example waits up to one second for a connection to be closed:
socket->disconnectFromHost(); if (socket->state() == QAbstractSocket::UnconnectedState || socket->waitForDisconnected(1000)) qDebug("Disconnected!");
If msecs is -1, this function will not time out.
public boolean atEnd()
This function is reimplemented for internal reasons.
atEnd
in class QIODevice
public long bytesAvailable()
Returns the number of incoming bytes that are waiting to be read.
bytesAvailable
in class QIODevice
public long bytesToWrite()
Returns the number of bytes that are waiting to be written. The bytes are written when control goes back to the event loop or when flush is called.
bytesToWrite
in class QIODevice
public boolean canReadLine()
Returns true if a line of data can be read from the socket; otherwise returns false.
canReadLine
in class QIODevice
public void close()
Disconnects the socket's connection with the host.
close
in class QIODevice
public boolean isSequential()
This function is reimplemented for internal reasons.
isSequential
in class QIODevice
protected int readData(byte[] data)
Equivalent to readData(data, ).
readData
in class QIODevice
protected int readLineData(byte[] data)
Equivalent to readLineData(data, ).
readLineData
in class QIODevice
public boolean waitForBytesWritten(int msecs)
This function is reimplemented for internal reasons.
waitForBytesWritten
in class QIODevice
public boolean waitForReadyRead(int msecs)
This function blocks until data is available for reading and the readyRead() signal has been emitted. The function will timeout after msecs milliseconds; the default timeout is 3000 milliseconds.
The function returns true if the readyRead signal is emitted and there is data available for reading; otherwise it returns false (if an error occurred or the operation timed out).
waitForReadyRead
in class QIODevice
protected int writeData(byte[] data)
Equivalent to writeData(data, ).
writeData
in class QIODevice
public static QAbstractSocket fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.public final void connectToHost(java.lang.String host, int port, QIODevice.OpenMode mode)
The socket is opened in the given mode and first enters HostLookupState, then performs a host name lookup of host. If the lookup succeeds, hostFound() is emitted and QAbstractSocket enters ConnectingState. It then attempts to connect to the address or addresses returned by the lookup. Finally, if a connection is established, QAbstractSocket enters ConnectedState and emits connected().
At any point, the socket can emit error() to signal that an error occurred.
host may be an IP address in string form (e.g., "43.195.83.32"), or it may be a host name (e.g., "www.trolltech.com"). QAbstractSocket will do a lookup only if required. port is in native byte order.
public final void connectToHost(QHostAddress host, int port, QIODevice.OpenMode mode)
protected final void connectToHostImplementation(java.lang.String host, int port, QIODevice.OpenMode mode)
Attempts to make a connection to host on the given port. The socket is opened in the given mode.
public final int localPort()
public final int peerPort()
protected final void setLocalPort(int port)
protected final void setPeerPort(int port)
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