QT 使用QUdpSocket QUdpServer UDP 建立客户端与服务器端

1. 模拟天气监控，每隔两秒从Server发送天气信息到Client.

2. 示例代码 

--------------------------- Server 端 -------------------------------------

修改工程文件.pro , QT += network， 添加net模块

udpsend.h

#ifndef UDPSEND_H
#define UDPSEND_H

#include <QWidget>
#include <QtGui>
#include <QtNetwork>

class udpSend : public QPushButton   //继承自QPushButton 双击退出
{
    Q_OBJECT
    
public:
    udpSend(QWidget *parent = 0);
    ~udpSend();

private slots:
    void sendDatagram();

private:
    QUdpSocket udpSocket;
    QTimer timer;
};

#endif // UDPSEND_H

udpsend.cpp

#include "udpsend.h"

udpSend::udpSend(QWidget *parent)
    : QPushButton(tr("clicked, quit"),parent)
{
    connect(this, SIGNAL(clicked()), this, SLOT(close()));
    connect(&timer, SIGNAL(timeout()), this, SLOT(sendDatagram())); //定时发送

    timer.start(2000);
    setSizeIncrement(100,100);
    setWindowTitle(tr("Weather Balloon"));
}

udpSend::~udpSend()
{    
}

void udpSend::sendDatagram()
{
    QByteArray datagram;
    QDataStream out(&datagram, QIODevice::WriteOnly);
    out.setVersion(QDataStream::Qt_4_7);
    out << QDateTime::currentDateTime() << qrand()/10000000.0 << qrand()/10000000.0 << qrand()/10000000.0 ;
    //发送主机可以用QHostAddress("127.0.0.1")替换
    udpSocket.writeDatagram(datagram, QHostAddress::LocalHost, 13999);  // UDP 发送数据
}

------------------------------- Client 端 ------------------------------------

 udpclient.h

#ifndef UDPCLIENT_H
#define UDPCLIENT_H

#include <QDialog>
#include <QtNetwork>
#include <QtGui>

class udpClient : public QDialog
{
    Q_OBJECT
    
public:
    udpClient(QWidget *parent = 0);
    ~udpClient();

private slots:
    void processPendingDatagrams();

private:
    QUdpSocket udpSocket;

    QLabel *dateLabel;
    QLabel *timeLabel;
    QLabel *tempLabel;
    QLabel *humLabel;
    QLabel *altiLabel;
    QLineEdit *dateEdit;
    QLineEdit *timeEdit;
    QLineEdit *tempEdit;
    QLineEdit *humEdit;
    QLineEdit *altiEdit;
};

#endif // UDPCLIENT_H

udpclient.cpp

#include "udpclient.h"

udpClient::udpClient(QWidget *parent)
    : QDialog(parent)
{
    udpSocket.bind(13999);   //建立监听
    connect(&udpSocket, SIGNAL(readyRead()), this, SLOT(processPendingDatagrams()));   //接收准备

    dateLabel = new QLabel(tr("Date"));
    timeLabel = new QLabel(tr("Time"));
    tempLabel = new QLabel(tr("Temp"));
    humLabel  = new QLabel(tr("Hum"));
    altiLabel = new QLabel(tr("Alti"));
    dateEdit  = new QLineEdit();
    timeEdit  = new QLineEdit();
    tempEdit  = new QLineEdit();
    humEdit   = new QLineEdit();
    altiEdit  = new QLineEdit();

    QGridLayout *gLayout = new QGridLayout;
    gLayout->addWidget(dateLabel, 0, 0);
    gLayout->addWidget(dateEdit, 0, 1);
    gLayout->addWidget(timeLabel, 1, 0);
    gLayout->addWidget(timeEdit, 1, 1);
    gLayout->addWidget(tempLabel, 2, 0);
    gLayout->addWidget(tempEdit, 2, 1);
    gLayout->addWidget(humLabel, 3, 0);
    gLayout->addWidget(humEdit, 3, 1);
    gLayout->addWidget(altiLabel, 4, 0);
    gLayout->addWidget(altiEdit, 4, 1);

    setLayout(gLayout);

}

udpClient::~udpClient()
{    
}

void udpClient::processPendingDatagrams()
{
    QByteArray datagram;
    do{
        datagram.resize(udpSocket.pendingDatagramSize());
        udpSocket.readDatagram(datagram.data(), datagram.size());  //接收数据
    }while( udpSocket.hasPendingDatagrams() );

    QDateTime dateTime;
    double temperature;
    double humidity;
    double altitude;

    QDataStream in(&datagram, QIODevice::ReadOnly);
    in.setVersion(QDataStream::Qt_4_7);
    in >> dateTime >> temperature >> humidity >> altitude;

    dateEdit->setText(dateTime.date().toString());
    timeEdit->setText(dateTime.time().toString());
    tempEdit->setText(tr("%1 C").arg(temperature));
    humEdit->setText(tr("%1 %").arg(humidity));
    altiEdit->setText(tr("%1 m").arg(altitude));

}