QT网络与通信：UDP客户端和服务端小实例

在.Pro文件中添加

QT += network

服务端：
在udpserver.h中添加

#ifndef UDPSERVER_H
#define UDPSERVER_H

#include <QDialog>
#include <QLabel>
#include<QLineEdit>
#include<QPushButton>
#include<QVBoxLayout>
#include<QUdpSocket>
#include<QTimer>
class udpserver : public QDialog
{
    Q_OBJECT

public:
    udpserver(QWidget *parent = 0,Qt::WindowFlags f=0);
    ~udpserver();
private:
    QLabel *TimeLabel;
    QLineEdit *TextLineEdit;
    QPushButton *StartBtn;
    QVBoxLayout *mainLayout;

    int port;
    bool isStarted;
    QUdpSocket *udpSocket;
    QTimer *timer;
private slots:
    void StartBtnClicked();
    void timeout();


};
#endif // UDPSERVER_H

在udpserver.cpp中添加

#include "udpserver.h"
#include <QHostAddress>
udpserver::udpserver(QWidget *parent,Qt::WindowFlags f)//构造函数
    : QDialog(parent,f)
{
    resize(200,150);
    setWindowTitle(tr("UDP Server"));
    TimeLabel =new QLabel(tr("计时器"),this);
    TextLineEdit =new QLineEdit(this);
    StartBtn =new QPushButton(tr("开始"));

    mainLayout =new QVBoxLayout(this);
    mainLayout->addWidget(TimeLabel);
    mainLayout->addWidget(TextLineEdit);
    mainLayout->addWidget(StartBtn);

    connect(StartBtn,SIGNAL(clicked()),this,SLOT(StartBtnClicked()));
    port=5555;//设置UDP的端口号参数，服务器定时向此端口发送广播参数
    isStarted =false;//开始没有启动
    udpSocket = new QUdpSocket(this);
    timer = new QTimer(this);

    connect(timer,SIGNAL(timeout()),this,SLOT(timeout));//定时发送广播
}
void udpserver::StartBtnClicked()
{
    if(!isStarted)
    {
        StartBtn->setText(tr("停止"));
        timer->start(1000);//开始启动计时器并执行1000毫秒，也就是1秒
        isStarted = true;//启动
    }
    else
    {
        StartBtn->setText(tr("开始"));
        isStarted =false;
        timer->stop();//停止计时
    }
}
void udpserver::timeout()
{
    QString msg=TextLineEdit->text();
    int length=0;
    if(msg=="")//为空则不输出
    {
        return ;
    }
    if((length=udpSocket->writeDatagram(msg.toLatin1(),msg.length(),QHostAddress::Broadcast,port))!=msg.length())
    {
        return ;
    }  //发送数据报到相应的端口
    //writeDatagram返回结果是发送成功的字节数
}
udpserver::~udpserver()
{
}

客户端：
在udpclient.h中添加

#ifndef UDPCLIENT_H
#define UDPCLIENT_H

#include <QDialog>
#include <QVBoxLayout>
#include <QTextEdit>
#include <QPushButton>
#include <QUdpSocket>
class udpclient : public QDialog
{
    Q_OBJECT

public:
    udpclient(QWidget *parent = 0,Qt::WindowFlags f=0);
    ~udpclient();
private:
    QTextEdit *receiveTextEdit;
    QVBoxLayout *mainLayout;
    QPushButton *closeBtn;
private slots:
    void CloseBtnClicked();
    void dataReceived();
private :
    int port;
    QUdpSocket *udpsocket;//操作系统和程序直接的连接

};
#endif // UDPCLIENT_H

在udpclient.cpp中添加

#include "udpclient.h"
#include <QMessageBox>
#include <QHostAddress>
udpclient::udpclient(QWidget *parent,Qt::WindowFlags f)
    : QDialog(parent,f)
{
    setWindowTitle(tr("客户端"));
    receiveTextEdit = new QTextEdit(this);
    closeBtn = new QPushButton(tr("关闭"),this);
    mainLayout =new QVBoxLayout(this);
    mainLayout->addWidget(receiveTextEdit);
    mainLayout->addWidget(closeBtn);

    connect(closeBtn,SIGNAL(clicked()),this,SLOT(CloseBtnClicked()));
    port=5555;
    udpsocket =new QUdpSocket(this);
    connect(udpsocket,SIGNAL(readyRead()),this,SLOT(dataReceived()));
    //readyRead()当有数据到达设备时，就触发这个信号
    bool result =udpsocket->bind(port);
    //用于未连接的数据报或流类套接口，把一本地地址与一套接口捆绑，在connect()或listen()调用前使用。
    if(!result)
    {
        QMessageBox::information(this,tr("error"),tr("udp socket create error!"));
        return ;
    }
    return ;
}
void udpclient::CloseBtnClicked()
{
    close();//关闭
}
void udpclient::dataReceived()
{
    while(udpsocket->hasPendingDatagrams())//判断是否有数据报可读
    {
        QByteArray datagram;
        datagram.resize(udpsocket->pendingDatagramSize());
        udpsocket->readDatagram(datagram.data(),datagram.size());//从操作系统中读出数据
        QString msg=datagram.data();
        receiveTextEdit->insertPlainText(msg);//显示数据内容
    }
}
udpclient::~udpclient()
{
}

具体函数已有注释！！！