com.trolltech.qt.network
Class QUdpSocket

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.core.QIODevice
                      extended by com.trolltech.qt.network.QAbstractSocket
                          extended by com.trolltech.qt.network.QUdpSocket
All Implemented Interfaces:
QtJambiInterface

public class QUdpSocket
extends QAbstractSocket

The QUdpSocket class provides a UDP socket. UDP (User Datagram Protocol) is a lightweight, unreliable, datagram-oriented, connectionless protocol. It can be used when reliability isn't important. QUdpSocket is a subclass of QAbstractSocket that allows you to send and receive UDP datagrams.

The most common way to use this class is to bind to an address and port using bind(), then call writeDatagram() and readDatagram() to transfer data. If you want to use the standard QIODevice functions read(), readLine(), write(), etc., you must first connect the socket directly to a peer by calling connectToHost().

The socket emits the bytesWritten() signal every time a datagram is written to the network. If you just want to send datagrams, you don't need to call bind().

The readyRead() signal is emitted whenever datagrams arrive. In that case, hasPendingDatagrams() returns true. Call pendingDatagramSize() to obtain the size of the first pending datagram, and readDatagram() to read it.

Example:

    public class Server extends QObject {
    private QUdpSocket udpSocket;

        public void initSocket()
        {
            udpSocket = new QUdpSocket(this);
            udpSocket.bind(new QHostAddress(QHostAddress.SpecialAddress.LocalHost), 7755);

            udpSocket.readyRead.connect(this, "readPendingDatagrams()");
        }

        public void readPendingDatagrams()
        {
            while (udpSocket.hasPendingDatagrams()) {
                byte[] datagram = new byte[(int)udpSocket.pendingDatagramSize()];
        QUdpSocket.HostInfo senderInfo = new QUdpSocket.HostInfo();

                udpSocket.readDatagram(datagram, senderInfo);

                // process the datagram
            }
        }
    }
With QUdpSocket, you can also establish a virtual connection to a UDP server using connectToHost() and then use read() and write() to exchange datagrams without specifying the receiver for each datagram.

The Broadcast Sender and Broadcast Receiver examples illustrate how to use QUdpSocket in applications.

See also:
QTcpSocket.


Nested Class Summary
static class QUdpSocket.BindFlag
          This enum describes the different flags you can pass to modify the behavior of QUdpSocket::bind().
static class QUdpSocket.BindMode
           
static class QUdpSocket.HostInfo
           
 
Nested classes/interfaces inherited from class com.trolltech.qt.network.QAbstractSocket
QAbstractSocket.NetworkLayerProtocol, QAbstractSocket.SocketError, QAbstractSocket.SocketState, QAbstractSocket.SocketType
 
Nested classes/interfaces inherited from class com.trolltech.qt.core.QIODevice
QIODevice.OpenMode, QIODevice.OpenModeFlag
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, 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
 
Fields inherited from class com.trolltech.qt.network.QAbstractSocket
connected, disconnected, error, hostFound, proxyAuthenticationRequired, stateChanged
 
Fields inherited from class com.trolltech.qt.core.QIODevice
aboutToClose, bytesWritten, readChannelFinished, readyRead
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QUdpSocket()
          Creates a QUdpSocket object.
QUdpSocket(QObject parent)
          Creates a QUdpSocket object.
 
Method Summary
 boolean bind()
           
 boolean bind(int port)
          Binds to QHostAddress.Any on port port.
 boolean bind(int port, QUdpSocket.BindFlag[] mode)
          Binds to address on port port, using the BindModemode.
 boolean bind(int port, QUdpSocket.BindMode mode)
          Binds to address on port port, using the BindModemode.
 boolean bind(QHostAddress address, int port)
          Binds this socket to the address address and the port port.
 boolean bind(QHostAddress address, int port, QUdpSocket.BindFlag[] mode)
          Binds to address on port port, using the BindModemode.
 boolean bind(QHostAddress address, int port, QUdpSocket.BindMode mode)
          Binds to address on port port, using the BindModemode.
 boolean hasPendingDatagrams()
          Returns true if at least one datagram is waiting to be read; otherwise returns false.
 long pendingDatagramSize()
          Returns the size of the first pending UDP datagram.
 int readDatagram(byte[] data)
          Receives a datagram no larger than maxSize bytes and stores it in data.
 int readDatagram(byte[] data, QUdpSocket.HostInfo info)
          Receives a datagram no larger than maxSize bytes and stores it in data.
 int writeDatagram(byte[] data, QHostAddress address, int port)
          Sends the datagram at data of size size to the host address address at port port.
 int writeDatagram(QByteArray data, QHostAddress address, int port)
          Sends the datagram datagram to the host address host and at port port.
 
Methods inherited from class com.trolltech.qt.network.QAbstractSocket
abort, connectToHost, connectToHost, connectToHost, connectToHost, connectToHost, connectToHost, disconnectFromHost, disconnectFromHostImplementation, error, flush, isValid, localAddress, localPort, peerAddress, peerName, peerPort, proxy, readBufferSize, setLocalAddress, setLocalPort, setPeerAddress, setPeerName, setPeerPort, setProxy, setReadBufferSize, setSocketDescriptor, setSocketDescriptor, setSocketDescriptor, setSocketDescriptor, setSocketError, setSocketState, socketDescriptor, socketType, state, waitForConnected, waitForConnected, waitForDisconnected, waitForDisconnected
 
Methods inherited from class com.trolltech.qt.core.QIODevice
atEnd, bytesAvailable, bytesToWrite, canReadLine, close, errorString, getByte, isOpen, isReadable, isSequential, isTextModeEnabled, isWritable, open, open, openMode, peek, peek, pos, putByte, read, read, readAll, readData, readLine, readLine, readLine, readLineData, reset, seek, setErrorString, setOpenMode, setOpenMode, setTextModeEnabled, size, ungetByte, waitForBytesWritten, waitForReadyRead, write, write, writeData
 
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
 

Constructor Detail

QUdpSocket

public QUdpSocket()
Creates a QUdpSocket object.

parent is passed to the QObject constructor.

See also:
socketType().


QUdpSocket

public QUdpSocket(QObject parent)
Creates a QUdpSocket object.

parent is passed to the QObject constructor.

See also:
socketType().

Method Detail

hasPendingDatagrams

public final boolean hasPendingDatagrams()
Returns true if at least one datagram is waiting to be read; otherwise returns false.

See also:
pendingDatagramSize(), and readDatagram().


pendingDatagramSize

public final long pendingDatagramSize()
Returns the size of the first pending UDP datagram. If there is no datagram available, this function returns -1.

See also:
hasPendingDatagrams(), and readDatagram().


bind

public final boolean bind(QHostAddress address,
                          int port)
Binds this socket to the address address and the port port. When bound, the signal readyRead() is emitted whenever a UDP datagram arrives on the specified address and port. This function is useful to write UDP servers.

On success, the functions returns true and the socket enters BoundState; otherwise it returns false.

The socket is bound using the DefaultForPlatform BindMode.


bind

public final boolean bind()

bind

public final boolean bind(int port)
Binds to QHostAddress.Any on port port.


bind

public final boolean bind(QHostAddress address,
                          int port,
                          QUdpSocket.BindFlag[] mode)
Binds to address on port port, using the BindModemode.


bind

public final boolean bind(QHostAddress address,
                          int port,
                          QUdpSocket.BindMode mode)
Binds to address on port port, using the BindModemode.


bind

public final boolean bind(int port,
                          QUdpSocket.BindFlag[] mode)
Binds to address on port port, using the BindModemode.


bind

public final boolean bind(int port,
                          QUdpSocket.BindMode mode)
Binds to address on port port, using the BindModemode.


readDatagram

public final int readDatagram(byte[] data,
                              QUdpSocket.HostInfo info)
Receives a datagram no larger than maxSize bytes and stores it in data. The sender's host address and port is stored in *address and *port (unless the pointers are 0).

Returns the size of the datagram on success; otherwise returns -1.

If maxSize is too small, the rest of the datagram will be lost. To avoid loss of data, call pendingDatagramSize() to determine the size of the pending datagram before attempting to read it. If maxSize is 0, the datagram will be discarded.

See also:
writeDatagram(), hasPendingDatagrams(), and pendingDatagramSize().


readDatagram

public final int readDatagram(byte[] data)
Receives a datagram no larger than maxSize bytes and stores it in data. The sender's host address and port is stored in *address and *port (unless the pointers are 0).

Returns the size of the datagram on success; otherwise returns -1.

If maxSize is too small, the rest of the datagram will be lost. To avoid loss of data, call pendingDatagramSize() to determine the size of the pending datagram before attempting to read it. If maxSize is 0, the datagram will be discarded.

See also:
writeDatagram(), hasPendingDatagrams(), and pendingDatagramSize().


writeDatagram

public final int writeDatagram(byte[] data,
                               QHostAddress address,
                               int port)
Sends the datagram at data of size size to the host address address at port port. Returns the number of bytes sent on success; otherwise returns -1.

Datagrams are always written as one block. The maximum size of a datagram is highly platform-dependent, but can be as low as 8192 bytes. If the datagram is too large, this function will return -1 and error() will return DatagramTooLargeError .

Sending datagrams larger than 512 bytes is in general disadvised, as even if they are sent successfully, they are likely to be fragmented by the IP layer before arriving at their final destination.

Warning: Calling this function on a connected UDP socket may result in an error and no packet being sent. If you are using a connected socket, use write() to send datagrams.

See also:
readDatagram(), and write().


writeDatagram

public final int writeDatagram(QByteArray data,
                               QHostAddress address,
                               int port)
Sends the datagram datagram to the host address host and at port port.