Qt通信之Udp(客户端和服务端)20.11.27

可以看出，在UDP方式下客户端并不与服务器建立连接，它只负责调用发送函数向服务器发送数据报。相同，服务器也不从客户端接收连接，只负责调用接收函数，等待来自某客户端的数据到达。
Qt中通过QUdpSocket类实现UDP协议的编程。接下来通过一个实例，介绍如何实现基于UDP协议的广播应用，它由UDP服务器和UDP客户端两部分组成。

首先是客户端（Client）

这个是接收到服务端返回的消息–渲染。
服务端(Server)

Edit是我发送给客户端的内容。

这个demo的目的–
我在服务端输入任意内容，并点击开始。他会把内容发给客户端。（我在服务端加了定时器，所以他会每秒发一次，所以客户端也会每秒接收一次内容）。

UdpClient.h

#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();

public slots:
    void CloseBtnClicked();
    void dataReceived();

private:
    QTextEdit *ReceiveTextEdit;
    QPushButton *CloseBtn;
    QVBoxLayout *mainLayout;

    int port;
    QUdpSocket *udpSocket;

};

#endif // UDPCLIENT_H

UdpClient.cpp

#include "udpclient.h"

#include <QMessageBox>
#include <QHostAddress>
UdpClient::UdpClient(QWidget *parent, Qt::WindowFlags f)
    : QDialog(parent, f)
{
    setWindowTitle(tr("UDP Client"));

    ReceiveTextEdit = new QTextEdit(this);
    CloseBtn = new QPushButton(tr("Close"), this);

    mainLayout = new QVBoxLayout(this);
    mainLayout->addWidget(ReceiveTextEdit);
    mainLayout->addWidget(CloseBtn);

    connect(CloseBtn, SIGNAL(clicked()), this, SLOT(CloseBtnClicked()));

    port = 555;

    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;
    }
}

UdpClient::~UdpClient()
{

}

void UdpClient::CloseBtnClicked()
{
    close();
}

void UdpClient::dataReceived()
{
    while(udpSocket->hasPendingDatagrams())
    {
        QByteArray datagram;
        datagram.resize(udpSocket->pendingDatagramSize());

        udpSocket->readDatagram(datagram.data(),datagram.size());
        QString msg = datagram.data();
        ReceiveTextEdit->insertPlainText(msg);
    }
}

UdpServer.h

#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);
    ~UdpServer();
public slots:
    void StartBtnClicked();
    void timeout();
private:
    QLabel *TimerLabel;
    QLineEdit *TextLineEdit;
    QPushButton *StartBtn;
    QVBoxLayout *mainLayout;

    int port;
    bool isStarted;
    QUdpSocket *udpSocket;
    QTimer *timer;
};

#endif // UDPSERVER_H

UdpServer.cpp

#include "udpserver.h"
#include <QHostAddress>
UdpServer::UdpServer(QWidget *parent)
    : QDialog(parent)
{
    setWindowTitle(tr("UDP Server"));

    TimerLabel = new QLabel(tr("计算器："), this);
    TextLineEdit = new QLineEdit(this);
    StartBtn = new QPushButton(tr("开始"), this);

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

    connect(StartBtn, SIGNAL(clicked()), this, SLOT(StartBtnClicked()));
    port = 555;
    isStarted=false;
    udpSocket = new QUdpSocket(this);
    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(timeout()));
}

UdpServer::~UdpServer()
{

}

void UdpServer::StartBtnClicked()
{
    if(!isStarted)
    {
        StartBtn->setText(tr("停止"));
        timer->start(1000);
        isStarted = true;
    }
    else
    {
        StartBtn->setText(tr("开始"));
        isStarted = false;
        timer->stop();
    }
}

void UdpServer::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;
    }
}

同时运行UdpServer和UdpClient工程。记住，要分为两个工程实现！
需要完整源码请移步我的CSDN资源。