Qt--基于UDP的网络广播

 用户数据报协议（User Data Protocol，UDP）是一种简单轻量级、不可靠、面向数据报、无连接的传输协议，可以应用在可靠性不是十分重要的场合，如短消息、广播信息等。
 UDP客户端向UDP服务器发送一定长度的请求报文，报文大小的限制于各系统的协议实现有关，但不得超过其下层IP协议规定的64KB；UDP服务器同样以报文形式作出响应。如果服务器未收到此请求，客户端进行重发，因此报文的传输是不可靠的。
Qt中通过QUdpSocket类实现UDP协议的编程。
UDP适用于以下几种情况：

• 网络数据大多是短消息
• 拥有大量的 客户端
• 对数据安全性无特殊要求
• 网络负担非常重，但对响应速度要求高

服务器端编程

MainWindow.h 头文件

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QDialog>#include <QLabel>#include <QLineEdit>#include <QPushButton>#include <QVBoxLayout>#include <QUdpSocket>#include <QTimer>class UDP_Server : public QDialog{    Q_OBJECTpublic:    UDP_Server(QWidget *parent = 0,Qt::WindowFlags f=0);    ~UDP_Server();public slots:    void StartBtnClicked();//按键点击槽函数声明    void timeout();private:    int port;//端口声明    bool isStarted;    QUdpSocket *udpSocket;//网络Socket声明    QTimer *timer;    QLabel *TimerLabel;    QLineEdit *TextLineEdit;    QPushButton *StartBtn;    QVBoxLayout *mainLayout;};#endif // MAINWINDOW_H

main.cpp 的内容

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[]){    QApplication a(argc, argv);    UDP_Server w;    w.show();    return a.exec();}

Mainwindow.cpp 内容

#include "mainwindow.h"#include <QHostAddress>UDP_Server::UDP_Server(QWidget *parent,Qt::WindowFlags f)    : QDialog(parent,f){    setWindowTitle("UDP Server");//设置窗体的标题    /*初始化各个控件*/    TimerLabel = new QLabel(tr("Timer:"),this);    TextLineEdit = new QLineEdit(this);    StartBtn = new QPushButton(tr("Start"),this);    /*设置布局*/    mainLayout = new QVBoxLayout(this);    mainLayout ->addWidget(TimerLabel);    mainLayout ->addWidget(TextLineEdit);    mainLayout ->addWidget(StartBtn);    connect(StartBtn,SIGNAL(clicked()),this,SLOT(StartBtnClicked()));    port =5555;    isStarted=false;    udpSocket = new QUdpSocket(this);    timer = new QTimer(this);    connect(timer,SIGNAL(timeout()),this,SLOT(timeout()));}UDP_Server::~UDP_Server(){}void UDP_Server::StartBtnClicked(){    if(!isStarted)    {        StartBtn->setText(tr("Stop"));        timer->start(1000);        isStarted =true;    }    else    {        StartBtn->setText(tr("Start"));        isStarted = false;        timer->stop();    }}void UDP_Server::timeout(){    QString msg = TextLineEdit->text();    int length=0;    if(msg=="")    {       return;    }    if((length=udpSocket->writeDatagram(msg.toLatin1(),msg.length(),QHostAddress::Broadcast,port))!=msg.length())    {        return;    }}

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客户端编程

MainWindow.h的程序：

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QMainWindow>#include <QDialog>#include <QVBoxLayout>#include <QTextEdit>#include <QPushButton>#include <QUdpSocket>class UDP_Client : public QDialog{    Q_OBJECTpublic:    UDP_Client(QWidget *parent = 0);    ~UDP_Client();public slots:    void CloseBtnClicked();    void dataReceived();    void CleanBtnClicked();private:    int port;    QUdpSocket *udpSocket;    QTextEdit *ReceiveTextEdit;    QPushButton *CloseBtn;    QPushButton *CleanBtn;    QVBoxLayout *mainLayout;};#endif // MAINWINDOW_H

main.cpp的程序：

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[]){    QApplication a(argc, argv);    UDP_Client w;    w.show();    return a.exec();}

MainWindow.cpp程序：

#include "mainwindow.h"#include <QMessageBox>#include <QHostAddress>UDP_Client::UDP_Client(QWidget *parent)    : QDialog(parent){    setWindowTitle(tr("UDP Client"));    /*初始化各个控件*/    ReceiveTextEdit = new QTextEdit(this);    CloseBtn = new QPushButton(tr("Close"),this);    CleanBtn = new QPushButton(tr("Clean"),this);    /*设置布局*/    mainLayout = new QVBoxLayout(this);    mainLayout->addWidget(ReceiveTextEdit);    mainLayout->addWidget(CloseBtn);    mainLayout->addWidget(CleanBtn);    connect(CloseBtn,SIGNAL(clicked()),this,SLOT(CloseBtnClicked()));    connect(CleanBtn,SIGNAL(clicked()),this,SLOT(CleanBtnClicked()));    port =5555;    udpSocket = new QUdpSocket(this);    connect(udpSocket,SIGNAL(readyRead()),this,SLOT(dataReceived()));    bool result=udpSocket->bind(port);    if(!result)    {        QMessageBox::information(this,tr("error"),tr("udp socket create error!"));        return;    }}UDP_Client::~UDP_Client(){}void UDP_Client::CloseBtnClicked(){    close();}void UDP_Client::CleanBtnClicked()//清空数据显示{    ReceiveTextEdit->clear();}void UDP_Client::dataReceived(){    while(udpSocket->hasPendingDatagrams())    {        QByteArray datagram;        datagram.resize(udpSocket->pendingDatagramSize());        udpSocket->readDatagram(datagram.data(),datagram.size());        QString msg=datagram.data();        ReceiveTextEdit->insertPlainText(msg);    }}