本系列所有文章可以在这里查看[http://blog.csdn.net/cloud_castle/article/category/2123873](http://blog.csdn.net/cloud_castle/article/category/2123873)
上次在该系列第一篇博文里提到QTcp的同步构建方式，这个例子涉及线程等，知识点比较多。我们还是由浅入深，今天再看个简单的例子吧~
按例看下Broadcast Sender Example的介绍吧，这对第一时间了解这个例程是有好处的~
Demonstrates how to broadcast information to multiple clients on a local network.
This example uses Qt Network APIs to demonstrate how to broadcast messages to multiple clients over a local network.
main主函数没有特别的东西，来看sender.h:
~~~
#ifndef SENDER_H
#define SENDER_H
#include <QWidget>
QT_BEGIN_NAMESPACE
class QDialogButtonBox;
class QLabel;
class QPushButton;
class QTimer;
class QUdpSocket;
QT_END_NAMESPACE
class Sender : public QWidget
{
Q_OBJECT
public:
Sender(QWidget *parent = 0);
private slots:
void startBroadcasting();
void broadcastDatagram();
private:
QLabel *statusLabel;
QPushButton *startButton;
QPushButton *quitButton;
QDialogButtonBox *buttonBox;
QUdpSocket *udpSocket;
QTimer *timer;
int messageNo;
};
#endif
~~~
可以发现这个头文件像Multicast Sender的头文件一样简单，甚至比它更简单。因为它连QHostAddress成员都没有。
sender.cpp:
~~~
#include <QtWidgets>
#include <QtNetwork>
#include "sender.h"
Sender::Sender(QWidget *parent)
: QWidget(parent)
{
statusLabel = new QLabel(tr("Ready to broadcast datagrams on port 45454"));
statusLabel->setWordWrap(true); // 这个属性的设置使得statusLabel的文字可以在合适的位置换行
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);
//! [0]
udpSocket = new QUdpSocket(this);
//! [0]
messageNo = 1;
connect(startButton, SIGNAL(clicked()), this, SLOT(startBroadcasting()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
connect(timer, SIGNAL(timeout()), this, SLOT(broadcastDatagram()));
QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(statusLabel);
mainLayout->addWidget(buttonBox);
setLayout(mainLayout);
setWindowTitle(tr("Broadcast Sender"));
}
void Sender::startBroadcasting()
{
startButton->setEnabled(false);
timer->start(1000);
}
void Sender::broadcastDatagram()
{
statusLabel->setText(tr("Now broadcasting datagram %1").arg(messageNo));
//! [1]
QByteArray datagram = "Broadcast message " + QByteArray::number(messageNo);
udpSocket->writeDatagram(datagram.data(), datagram.size(), // 第（1）点
QHostAddress::Broadcast, 45454);
//! [1]
++messageNo;
}
~~~
第一点，发送数据的语句就这一条，与Multicast唯一的区别在于使用了一个QHostAddress的枚举变量Broadcast，它相当于QHostAddress（“255,255,255,255”）。
好了，来看Broadcast Receiver的实现。receiver.h:
~~~
#ifndef RECEIVER_H
#define RECEIVER_H
#include <QWidget>
QT_BEGIN_NAMESPACE
class QLabel;
class QPushButton;
class QUdpSocket;
class QAction;
QT_END_NAMESPACE
class Receiver : public QWidget
{
Q_OBJECT
public:
Receiver(QWidget *parent = 0);
private slots:
void processPendingDatagrams();
private:
QLabel *statusLabel;
QPushButton *quitButton;
QUdpSocket *udpSocket;
};
#endif
~~~
receiver.cpp:
~~~
#include <QtWidgets> // 第（1）点
#include <QtNetwork>
#include "receiver.h"
Receiver::Receiver(QWidget *parent)
: QWidget(parent)
{
statusLabel = new QLabel(tr("Listening for broadcasted messages"));
statusLabel->setWordWrap(true);
quitButton = new QPushButton(tr("&Quit"));
//! [0]
udpSocket = new QUdpSocket(this);
udpSocket->bind(45454, QUdpSocket::ShareAddress); // 绑定端口，共享地址模式
//! [0]
//! [1]
connect(udpSocket, SIGNAL(readyRead()),
this, SLOT(processPendingDatagrams()));
//! [1]
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
QHBoxLayout *buttonLayout = new QHBoxLayout; // 以控件为Layout命名，而不是Layout1,Layout2...
buttonLayout->addStretch(1);
buttonLayout->addWidget(quitButton);
buttonLayout->addStretch(1);
QVBoxLayout *mainLayout = new QVBoxLayout; // 最外层的布局mainLayout
mainLayout->addWidget(statusLabel);
mainLayout->addLayout(buttonLayout);
setLayout(mainLayout);
setWindowTitle(tr("Broadcast Receiver"));
}
void Receiver::processPendingDatagrams() // 接收端的处理函数与Multicast一模一样
{
//! [2]
while (udpSocket->hasPendingDatagrams()) {
QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
udpSocket->readDatagram(datagram.data(), datagram.size());
statusLabel->setText(tr("Received datagram: \"%1\"")
.arg(datagram.data()));
}
//! [2]
}
~~~
第一点，个人不推荐这种头文件的包含方式，官方Demo为了简明这样做了，但这样会使包含的文件过多，最好用到什么包含什么，虽然会多写几个#include，但是预编译结束后文件体积会小很多。而且#include优于#include，这样头文件的层次更清晰。
好了，其实这个例子与上一个Multicast Sender/Receiver 基本没有多大区别，但是我们读例程并不只是关注它核心功能的实现，更多的在于细节的处理。细节决定成败嘛~
- 前言
- 1——Fortune Server/Client
- 2——Multicast Sender/Receiverz
- 3——Broadcast Sender/Receiver
- 4——Blocking Fortune Client
- 5——Threaded Fortune Server
- 5(总结)——Fortune例程的各个实现区别
- 6——Loopback Example
- 7——Analog Clock Example
- 8——Shaped Clock Example
- 9——Analog Clock Window Example
- 10——Qt Quick Particles Examples - Emitters
- 11——Qt Quick Particles Examples - Affectors
- 12——Qt Quick Particles Examples - CustomParticles
- 13——Qt Quick Particles Examples - Image Particles
- 14——Qt Quick Particles Examples - System
- 15——Chapter 1: Creating a New Type
- 16——Chapter 2: Connecting to C++ Methods and Signals
- 17——Chapter 3: Adding Property Bindings
- 18——Chapter 4: Using Custom Property Types
- 19——Chapter 5: Using List Property Types
- 20——Chapter 6: Writing an Extension Plugin
- 21——Extending QML - Adding Types Example
- 22——Extending QML - Object and List Property Types Example
- 23——Extending QML - Inheritance and Coercion Example
- 24——Extending QML - Default Property Example
- 25——Extending QML - Methods Example
- 26——Extending QML - Grouped Properties Example
- 27——Extending QML - Attached Properties Example
- 28——Extending QML - Signal Support Example
- 29——Extending QML - Property Value Source Example
- 30——Extending QML - Binding Example
- 31——StocQt
- 32——Qt Quick Examples - Threading
- 33——Qt Quick Examples - Window and Screen
- 34——Concentric Circles Example
- 35——Music Player
- 36——Wiggly Example
- 37——Vector Deformation