目錄

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Multicast Receiver Example

Multicast Sender Example

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Multicast Receiver Example

多播接收實(shí)例！

要注意幾點(diǎn)：

1.這個(gè)組播QHostAddress最好是填寫(xiě)D類(lèi)IP，填A(yù)BC類(lèi)在某些情況下可以的，因?yàn)槁酚善髂J(rèn)D類(lèi)是組播地址，所以為了避免不必要的麻煩，最好是D類(lèi)！

2.QHostAddress配的D類(lèi)地址，與真實(shí)IP地址一般是不一樣的；

3.調(diào)用joinMulticastGroup()函數(shù)把組播地址加入到socket中，使得數(shù)據(jù)包能夠成功接收！

4.bind()的時(shí)候，記得QHostAddress::AnyIPv4讓其接收所有的組播包！

5.每一組組播源最好設(shè)置同一個(gè)QHostAddress（可以設(shè)成不一樣，但可能會(huì)不通，這里關(guān)鍵看路由器，交換機(jī)的配置狀態(tài)）！

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源碼如下：

receiver.h

#ifndef RECEIVER_H #define RECEIVER_H#include <QDialog> #include <QHostAddress>QT_BEGIN_NAMESPACE class QLabel; class QPushButton; class QUdpSocket; QT_END_NAMESPACEclass Receiver : public QDialog {Q_OBJECTpublic:Receiver(QWidget *parent = 0);private slots:void processPendingDatagrams();private:QLabel *statusLabel;QPushButton *quitButton;QUdpSocket *udpSocket;QHostAddress groupAddress; };#endif

main.cpp

#include <QApplication>#include "receiver.h"int main(int argc, char *argv[]) {QApplication app(argc, argv);Receiver receiver;receiver.show();return app.exec(); }

receiver.cpp

#include <QtWidgets> #include <QtNetwork>#include "receiver.h"Receiver::Receiver(QWidget *parent): QDialog(parent) {groupAddress = QHostAddress("239.255.43.21");statusLabel = new QLabel(tr("Listening for multicasted messages"));quitButton = new QPushButton(tr("&Quit"));udpSocket = new QUdpSocket(this);udpSocket->bind(QHostAddress::AnyIPv4, 45454, QUdpSocket::ShareAddress);udpSocket->joinMulticastGroup(groupAddress);connect(udpSocket, SIGNAL(readyRead()),this, SLOT(processPendingDatagrams()));connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));QHBoxLayout *buttonLayout = new QHBoxLayout;buttonLayout->addStretch(1);buttonLayout->addWidget(quitButton);buttonLayout->addStretch(1);QVBoxLayout *mainLayout = new QVBoxLayout;mainLayout->addWidget(statusLabel);mainLayout->addLayout(buttonLayout);setLayout(mainLayout);setWindowTitle(tr("Multicast Receiver")); }void Receiver::processPendingDatagrams() {while (udpSocket->hasPendingDatagrams()) {QByteArray datagram;datagram.resize(udpSocket->pendingDatagramSize());udpSocket->readDatagram(datagram.data(), datagram.size());statusLabel->setText(tr("Received datagram: \"%1\"").arg(datagram.data()));} }

Multicast Sender Example

組播發(fā)送案例

注意點(diǎn)：

1.要設(shè)置TTL（Time To Live），這個(gè)是只在三層才有的，每經(jīng)過(guò)一個(gè)路由器TTL減1，廣播一般是二層的，所以沒(méi)有TTL這個(gè)概念，TTL這個(gè)的好處，可以避免網(wǎng)絡(luò)風(fēng)暴等，讓路由器開(kāi)銷(xiāo)過(guò)大！

2.setSocketOption()第一個(gè)參數(shù)是告訴socket發(fā)送的是什么包，比如廣播包！

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源碼如下：

sender.h

#ifndef SENDER_H #define SENDER_H#include <QDialog> #include <QHostAddress>QT_BEGIN_NAMESPACE class QDialogButtonBox; class QLabel; class QPushButton; class QTimer; class QUdpSocket; class QSpinBox; QT_END_NAMESPACEclass Sender : public QDialog {Q_OBJECTpublic:Sender(QWidget *parent = 0);private slots:void ttlChanged(int newTtl);void startSending();void sendDatagram();private:QLabel *statusLabel;QLabel *ttlLabel;QSpinBox *ttlSpinBox;QPushButton *startButton;QPushButton *quitButton;QDialogButtonBox *buttonBox;QUdpSocket *udpSocket;QTimer *timer;QHostAddress groupAddress;int messageNo; };#endif

main.cpp

#include <QApplication>#include "sender.h"int main(int argc, char *argv[]) {QApplication app(argc, argv);Sender sender;sender.show();return app.exec(); }

sender.cpp

#include <QtWidgets> #include <QtNetwork>#include "sender.h"Sender::Sender(QWidget *parent): QDialog(parent) {groupAddress = QHostAddress("239.255.43.21");statusLabel = new QLabel(tr("Ready to multicast datagrams to group %1 on port 45454").arg(groupAddress.toString()));ttlLabel = new QLabel(tr("TTL for multicast datagrams:"));ttlSpinBox = new QSpinBox;ttlSpinBox->setRange(0, 255);QHBoxLayout *ttlLayout = new QHBoxLayout;ttlLayout->addWidget(ttlLabel);ttlLayout->addWidget(ttlSpinBox);startButton = new QPushButton(tr("&Start"));quitButton = new QPushButton(tr("&Quit"));buttonBox = new QDialogButtonBox;buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);timer = new QTimer(this);udpSocket = new QUdpSocket(this);messageNo = 1;connect(ttlSpinBox, SIGNAL(valueChanged(int)), this, SLOT(ttlChanged(int)));connect(startButton, SIGNAL(clicked()), this, SLOT(startSending()));connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));connect(timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));QVBoxLayout *mainLayout = new QVBoxLayout;mainLayout->addWidget(statusLabel);mainLayout->addLayout(ttlLayout);mainLayout->addWidget(buttonBox);setLayout(mainLayout);setWindowTitle(tr("Multicast Sender"));ttlSpinBox->setValue(1); }void Sender::ttlChanged(int newTtl) {udpSocket->setSocketOption(QAbstractSocket::MulticastTtlOption, newTtl); }void Sender::startSending() {startButton->setEnabled(false);timer->start(1000); }void Sender::sendDatagram() {statusLabel->setText(tr("Now sending datagram %1").arg(messageNo));QByteArray datagram = "Multicast message " + QByteArray::number(messageNo);udpSocket->writeDatagram(datagram.data(), datagram.size(),groupAddress, 45454);++messageNo; }

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