[网络协议] QT笔记——网络通信之 QUdpSocket

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[网络协议]QT笔记——网络通信之 QUdpSocket

UDP(用户数据报协议)，是一个轻量的，不可靠的，面向数据报的，非连接的协议。当通讯要求的可靠性不重要时（可能数据会丢失），可以用UDP通信

.pro文件中添加网络模块 QT += network
头文件：#include<QUdpSocket>
重要函数：

bind()                   //服务器绑定端口
hasPendingDatagrams()    //当数据发来时，至少有一个数据报需要读取。
writeDatagram(const char *data, qint64 size, const QHostAddress &address, quint16 port)        //函数向指定的地址host和端口port发送数据报datagram，返回成功发送的字节数，数据报不要太长，不要超过512Byte
readDatagram(char *data, qint64 maxSize, QHostAddress *address = nullptr, quint16 *port = nullptr) 
pendingDatagramSize()   //函数第一个待读取的数据报的大小Byte。
joinMulticastGroup()	//函数使socket加入一个多播组groupAddress。
leaveMulticastGroup()   //函数使socket离开多播组groupAddress。

设计一下UI：
在这里插入图片描述
服务器：
1.绑定端口

m_udpSocket->bind(QHostAddress::AnyIPv4,8888);

2.发送消息和读取消息
2.1发送消息

//获取信息
QString sendStr = ui.sendTextEdit->toPlainText();
quint16 port = ui.portLineEdit->text().toInt();
QString ip = ui.IPlineEdit->text();
m_udpSocket->writeDatagram(sendStr.toUtf8(), QHostAddress(ip), port);

//连接socket  读取发送过来消息
connect(m_udpSocket, &QUdpSocket::readyRead, this, &QUdpTest::readValue);

2.2读取消息

while (m_udpSocket->hasPendingDatagrams())
{
	QByteArray array;
	//array.resize(m_udpSocket->bytesAvailable());
	array.resize(m_udpSocket->pendingDatagramSize());
	QHostAddress address;
	quint16 port;
	m_udpSocket->readDatagram(array.data(), array.size(),&address,&port);
	qDebug() << QStringLiteral("传过来的大小为：") << array.size();

	//用读取数据流
	//QDataStream read(&array, QIODevice::ReadOnly); 
	//Person p;
	//read >> p.name >> p.age >> p.score ;
	//QString str = QString("%1 %2 %3").arg(QString::number(p.age)).arg(p.name).arg(QString::number(p.score));	
	qDebug() << array.data();
	
	//读取发来的结构体（强转为我们需要转化的结构体）
	Person* p = reinterpret_cast<Person*>(array.data());
	QString str1 = QString(QLatin1String(p->name));
	QString str = QString("%1 %2 %3").arg(QString::number(p->age)).arg(str1).arg(QString::number(p->score));
	ui.recvTextEdit->setText(str);
}

客户端：
1.绑定端口

m_socket->bind(QHostAddress::AnyIPv4,9999);

2.发送消息和读取消息
2.1发送消息

quint16 port = ui.portLineEdit->text().toInt();
QString ip = ui.IPLineEdit->text();
QString sendStr = ui.sendTextEdit->toPlainText();
Person p1;
strcpy(p1.name, "xm");
p1.age = 20;
p1.score = 60;

//发送数据流
//QByteArray text_data;
//QDataStream write(&text_data, QIODevice::WriteOnly);
//write << p1.name << p1.age << p1.score ;
//m_socket->writeDatagram(text_data, text_data.size(), QHostAddress(ip), port);

//发送输入框中的内容
//m_socket->writeDatagram(sendStr.toUtf8(),QHostAddress(ip), port);
//m_socket->writeDatagram(sendStr.toLocal8Bit(), sendStr.size(), QHostAddress(ip), port);	

//发送结构体
m_socket->writeDatagram(( char*)&p1, sizeof(Person), QHostAddress(ip), port);
qDebug() << QStringLiteral("发送的数据大小：") << sizeof(p1);

2.2读取消息

while (m_socket->hasPendingDatagrams())
{
	QByteArray array;
	//array.resize(m_socket->bytesAvailable());//根据可读数据来设置空间大小
	array.resize(m_socket->pendingDatagramSize());
	QHostAddress address;
	quint16 port;
	m_socket->readDatagram(array.data(), array.size(), &address, &port);
	ui.recvTextEdit->setText(array);
}

3.客户端和服务端都加入组播
UDP组播是主机间一对一组的通信模式，当多个客户端加入由一个组播地址定义的多播组后，客户端向这个组播地址和端口发送的UDP数据报，组内成员都可以接收到。

m_socket->joinMulticastGroup(QHostAddress("224.0.0.100"));

完整代码：
QUdpTest.h

#pragma once
#include <QtWidgets/QWidget>
#include "ui_QUdpTest.h"
#include <QUdpSocket>
#include <QDebug>
class QUdpTest : public QWidget
{
	Q_OBJECT
	struct Person
	{
		char  name[20];
		int age;
		int score;
		Person()
		{
			memset(name, 0, 20);
			age = 0;
			score = 0;
		}
	};
public:
	QUdpTest(QWidget *parent = Q_NULLPTR);
	~QUdpTest();

public slots:
	  void readValue();
	  void on_sendBtn_clicked();
	  void on_delBtn_clicked();
private:
	Ui::QUdpTestClass ui;
	QUdpSocket* m_udpSocket;
};

QUdpTest.cpp

#include "QUdpTest.h"
#include <QDebug>
#include <QByteArray>
#include <QString>
#include <QLatin1String>
QUdpTest::QUdpTest(QWidget *parent)
	: QWidget(parent)
{
	ui.setupUi(this);
	m_udpSocket = new QUdpSocket(this);

	this->setWindowTitle(QStringLiteral("绑定端口号为：8888"));
	//绑定端口
	m_udpSocket->bind(QHostAddress::AnyIPv4,8888);
	m_udpSocket->joinMulticastGroup(QHostAddress("224.0.0.100"));
	connect(m_udpSocket, &QUdpSocket::readyRead, this, &QUdpTest::readValue);
	ui.recvTextEdit->setReadOnly(true);
}

QUdpTest::~QUdpTest()
{

}

void QUdpTest::readValue()
{
	while (m_udpSocket->hasPendingDatagrams())
	{
		QByteArray array;
		//array.resize(m_udpSocket->bytesAvailable());
		array.resize(m_udpSocket->pendingDatagramSize());
		QHostAddress address;
		quint16 port;
		m_udpSocket->readDatagram(array.data(), array.size(),&address,&port);
		qDebug() << QStringLiteral("传过来的大小为：") << array.size();

		//QDataStream read(&array, QIODevice::ReadOnly);  //读取数据流
		//Person p;
		//read >> p.name >> p.age >> p.score ;
		//QString str = QString("%1 %2 %3").arg(QString::number(p.age)).arg(p.name).arg(QString::number(p.score));
		qDebug() << array.data();
		Person* p = reinterpret_cast<Person*>(array.data());
		QString str1 = QString(QLatin1String(p->name));
		QString str = QString("%1 %2 %3").arg(QString::number(p->age)).arg(str1).arg(QString::number(p->score));
		ui.recvTextEdit->setText(str);
	}
}

void QUdpTest::on_sendBtn_clicked()
{
	//获取信息
	QString sendStr = ui.sendTextEdit->toPlainText();
	quint16 port = ui.portLineEdit->text().toInt();
	QString ip = ui.IPlineEdit->text();
	m_udpSocket->writeDatagram(sendStr.toUtf8(), QHostAddress(ip), port);
}

void QUdpTest::on_delBtn_clicked()
{
	m_udpSocket->leaveMulticastGroup(QHostAddress("224.0.0.100"));
}

QUdpTest1.h

#pragma once
#include <QWidget>
#include "ui_QUdpTest1.h"
#include <QUdpSocket>
class QUdpTest1 : public QWidget
{
	Q_OBJECT
	struct Person
	{
		char  name[20];
		int age;
		int score;
		Person()
		{
			memset(name, 0, 20);
			age = 0;
			score = 0;
		}
	};
public:
	QUdpTest1(QWidget *parent = Q_NULLPTR);
	~QUdpTest1();
public slots:
	void readValue();
	void on_sendBtn_clicked();
	void on_delBtn_clicked();
private:
	Ui::QUdpTest1 ui;
	QUdpSocket* m_socket;
};

QUdpTest1.cpp

#include "QUdpTest1.h"
#include <string.h>
QUdpTest1::QUdpTest1(QWidget *parent)
	: QWidget(parent)
{
	ui.setupUi(this);
	m_socket = new QUdpSocket(this);
	this->setWindowTitle(QStringLiteral("绑定端口为：9999"));
	m_socket->bind(QHostAddress::AnyIPv4,9999);
	m_socket->joinMulticastGroup(QHostAddress("224.0.0.100"));
	connect(m_socket, &QUdpSocket::readyRead, this, &QUdpTest1::readValue);
	ui.recvTextEdit->setReadOnly(true);
}

QUdpTest1::~QUdpTest1()
{
}

void QUdpTest1::readValue()
{
	while (m_socket->hasPendingDatagrams())
	{
		QByteArray array;
		//array.resize(m_socket->bytesAvailable());//根据可读数据来设置空间大小
		array.resize(m_socket->pendingDatagramSize());
		QHostAddress address;
		quint16 port;
		m_socket->readDatagram(array.data(), array.size(), &address, &port);
		ui.recvTextEdit->setText(array);
	}	
}

void QUdpTest1::on_sendBtn_clicked()
{
	quint16 port = ui.portLineEdit->text().toInt();
	QString ip = ui.IPLineEdit->text();
	QString sendStr = ui.sendTextEdit->toPlainText();
	Person p1;
	strcpy(p1.name, "xm");
	p1.age = 20;
	p1.score = 60;

	//QByteArray text_data;
	//QDataStream write(&text_data, QIODevice::WriteOnly);
	//write << p1.name << p1.age << p1.score ;
	//m_socket->writeDatagram(text_data, text_data.size(), QHostAddress(ip), port);

	//m_socket->writeDatagram(sendStr.toUtf8(),QHostAddress(ip), port);
	//m_socket->writeDatagram(sendStr.toLocal8Bit(), sendStr.size(), QHostAddress(ip), port);
	
	m_socket->writeDatagram(( char*)&p1, sizeof(Person), QHostAddress(ip), port);
	qDebug() << QStringLiteral("发送的数据大小：") << sizeof(p1);
}

void QUdpTest1::on_delBtn_clicked()
{
	m_socket->leaveMulticastGroup(QHostAddress("224.0.0.100"));
}