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java.lang.Objectcom.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.core.QSocketNotifier
public class QSocketNotifier
The QSocketNotifier class provides support for monitoring activity on a file descriptor. The QSocketNotifier makes it possible to integrate Qt's event loop with other event loops based on file descriptors. For example, the CORBA Framework uses it to process CORBA events. File descriptor action is detected in Qt's main event loop (QCoreApplication::exec()
). Once you have opened a device using a low-level (usually platform-specific) API, you can create a socket notifier to monitor the file descriptor. The socket notifier is enabled by default, i.e. it emits the activated()
signal whenever a socket event corresponding to its type occurs. Connect the activated()
signal to the slot you want to be called when an event corresponding to your socket notifier's type occurs.
There are three types of socket notifiers: read, write, and exception. The type is described by the Type
enum, and must be specified when constructing the socket notifier. After construction it can be determined using the type()
function. Note that if you need to monitor both reads and writes for the same file descriptor, you must create two socket notifiers. Note also that it is not possible to install two socket notifiers of the same type (Read
, Write
, Exception
) on the same socket.
The setEnabled()
function allows you to disable as well as enable the socket notifier. It is generally advisable to explicitly enable or disable the socket notifier, especially for write notifiers. A disabled notifier ignores socket events (the same effect as not creating the socket notifier). Use the isEnabled()
function to determine the notifier's current status.
Finally, you can use the socket()
function to retrieve the socket identifier. Although the class is called QSocketNotifier, it is normally used for other types of devices than sockets. QTcpSocket
and QUdpSocket
provide notification through signals, so there is normally no need to use a QSocketNotifier on them.Notes for Windows Users
The socket passed to QSocketNotifier will become non-blocking, even if it was created as a blocking socket. The activated()
signal is sometimes triggered by high general activity on the host, even if there is nothing to read. A subsequent read from the socket can then fail, the error indicating that there is no data available (e.g., WSAEWOULDBLOCK). This is an operating system limitation, and not a bug in QSocketNotifier.
To ensure that the socket notifier handles read notifications correctly, follow these steps when you receive a notification:
QFile
, QProcess
, QTcpSocket
, and QUdpSocket
.
Nested Class Summary | |
---|---|
static class |
QSocketNotifier.Type
This enum describes the various types of events that a socket notifier can recognize. |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9 |
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal |
Field Summary | |
---|---|
QSignalEmitter.Signal1 |
activated
This signal takes 1 generic argument(s). |
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
currentSender |
Constructor Summary | |
---|---|
QSocketNotifier(int socket,
QSocketNotifier.Type arg__2)
Constructs a socket notifier with the given parent. |
|
QSocketNotifier(int socket,
QSocketNotifier.Type arg__2,
QObject parent)
Constructs a socket notifier with the given parent. |
Method Summary | |
---|---|
boolean |
isEnabled()
Returns true if the notifier is enabled; otherwise returns false. |
void |
setEnabled(boolean arg__1)
If enable is true, the notifier is enabled; otherwise the notifier is disabled. |
int |
socket()
Returns the socket identifier specified to the constructor. |
QSocketNotifier.Type |
type()
Returns the socket event type specified to the constructor. |
Methods inherited from class com.trolltech.qt.core.QObject |
---|
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty |
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
__qt_signalInitialization |
Methods inherited from class java.lang.Object |
---|
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Field Detail |
---|
public final QSignalEmitter.Signal1 activated
This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <java.lang.Integer(named: socket)>:
This signal is emitted whenever the socket notifier is enabled and a socket event corresponding to its type
occurs.
The socket identifier is passed in the socket parameter.
type()
, and socket()
.
Constructor Detail |
---|
public QSocketNotifier(int socket, QSocketNotifier.Type arg__2)
It is generally advisable to explicitly enable or disable the socket notifier, especially for write notifiers.
Note for Windows users: The socket passed to QSocketNotifier will become non-blocking, even if it was created as a blocking socket.
setEnabled()
, and isEnabled()
.
public QSocketNotifier(int socket, QSocketNotifier.Type arg__2, QObject parent)
It is generally advisable to explicitly enable or disable the socket notifier, especially for write notifiers.
Note for Windows users: The socket passed to QSocketNotifier will become non-blocking, even if it was created as a blocking socket.
setEnabled()
, and isEnabled()
.
Method Detail |
---|
public final boolean isEnabled()
setEnabled()
.
public final void setEnabled(boolean arg__1)
The notifier is enabled by default, i.e. it emits the activated()
signal whenever a socket event corresponding to its type
occurs. If it is disabled, it ignores socket events (the same effect as not creating the socket notifier).
Write notifiers should normally be disabled immediately after the activated()
signal has been emitted
isEnabled()
, and activated()
.
public final int socket()
type()
.
public final QSocketNotifier.Type type()
socket()
.
|
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