Qt第十九章 网络编程

主机（Host）

QHostInfo

    // 阻塞获取网址信息QHostInfo info = QHostInfo::fromName("www.bilibili.com");qDebug() << info.hostName(); // 主机名即域名qDebug() << info.addresses(); // Ip地址// 异步获取，如果网址不存在会报错QHostInfo::lookupHost("www.baidu.com", &a, [=](const QHostInfo info1) { // a是 QCoreApplication a(argc, argv)qDebug() << info1.hostName();qDebug() << info1.addresses();});// 获取本地主机名qDebug() << "本地主机名" << QHostInfo::localHostName();

QHostAddress

枚举	描述	相当于
QHostAddress::Null	空地址对象	QHostAddress()
QHostAddress::LocalHost	IPv4本地主机地址	QHostAddress(127.0.0.1)
QHostAddress::LocalHostIPv6	IPv6本地主机地址	QHostAddress(“::1”)
QHostAddress::Broadcast	IPv4广播地址	QHostAddress(“255.255.255.255”)
QHostAddress::AnyIPv4	任意IPv4地址,与此绑定的套接字将只侦听iPV4接口	QHostAddress(“0.0.0.0”)
QHostAddress::AnyIPv6	任意IPv6地址	QHostAddress(“::”)
QHostAddress::Any	双栈任意地址。

QNetworkInterface

    QList<QNetworkInterface> netlist = QNetworkInterface::allInterfaces();for (auto& net : netlist) {if (!net.isValid())continue;qDebug() << "名称" << net.name();qDebug() << "描述" << net.humanReadableName();qDebug() << "类型" << net.type();qDebug() << "mac地址" << net.hardwareAddress();for (auto& ip : net.addressEntries())qDebug() << ip.ip();qDebug() << "==========================";        }

低级接口

QAbstractSocket

QTcpServer

创建服务器

#include <QCoreApplication>
#include <QHostInfo>
#include <QTcpServer>
#include <QTcpSocket>int main(int argc, char* argv[])
{QCoreApplication a(argc, argv);QTcpServer* server = new QTcpServer;server->listen(QHostAddress::LocalHost, 6666);QObject::connect(server, &QTcpServer::newConnection, [=] {while (server->hasPendingConnections()) { // 如果有连接，读取套接字QTcpSocket* socket = server->nextPendingConnection();socket->write("hello world!");qDebug() << "有新的连接来了";}});return a.exec();
}

QTcpSocket

// 创建客户端

    QTcpSocket* tcp = new QTcpSocket;QObject::connect(tcp, &QTcpSocket::errorOccurred, [=](QAbstractSocket::SocketError err) {qDebug() << err << '\t' << tcp->errorString();}); // 连接发生错误，报错误原因QObject::connect(tcp, &QTcpSocket::stateChanged, [=](auto state) {qDebug() << state;});QObject::connect(tcp, &QTcpSocket::connected, [] { qDebug("连接成功"); });QObject::connect(tcp, &QTcpSocket::readyRead, [=] {if (tcp->bytesAvailable() > 0)qDebug() << tcp->readAll();}); // 如果有可读取数据，读取所有并输出tcp->connectToHost(QHostAddress::LocalHost, 6666); // 连接本地地址，端口0-1023是被占用的，程序员可用1024-65535

QUdpSocket

单播

#include <QCoreApplication>
#include <QNetworkDatagram>
#include <QUdpSocket>int main(int argc, char* argv[])
{QCoreApplication a(argc, argv);QUdpSocket* udp1 = new QUdpSocket;QUdpSocket* udp2 = new QUdpSocket;udp2->bind(QHostAddress::LocalHost, 6666); // 绑定端口号QObject::connect(udp2, &QUdpSocket::readyRead, [=] {while (udp2->hasPendingDatagrams()) {qDebug() << udp2->receiveDatagram().data();}}); // 如果udp2里有接收到数据报，就打印udp1->writeDatagram("hello,world", QHostAddress::LocalHost, 6666); // 发送数据return a.exec();
}

多播

多播是一对多，与单播步骤是一样的，只有IP地址有区别
多播的地址是D类地址，即224.0.0.0到239.255.255.255之间的IP地址，并被划分为局部连接多播地址、预留多播地址和管理权限多播地址3类

1. 局部多播地址：224.0.0.0~224.0.0.255之间，这是为路由协议和其他用途保留的地址，路由器并不转发此范围的IP包
2. 预留多播地址：224.0.1.0~238.255.255.255之间，可用于全球范围（如Internet）或网络协议。
3. 管理权限多播地址：239.0.0.0~239.255.255.255之间，可供组织内部使用，类似于私有IP地址，不能用于Internet，可限制多播范围。

#include <QCoreApplication>
#include <QNetworkDatagram>
#include <QUdpSocket>int main(int argc, char* argv[])
{QCoreApplication a(argc, argv);QUdpSocket* udp1 = new QUdpSocket;QUdpSocket* udp2 = new QUdpSocket;// 组播udp2->bind(QHostAddress::AnyIPv4, 6666, QUdpSocket::ShareAddress | QUdpSocket::ReuseAddressHint);udp2->joinMulticastGroup(QHostAddress("224.1.1.1"));QObject::connect(udp2, &QUdpSocket::readyRead, [=] {while (udp2->hasPendingDatagrams()) {qDebug() << udp2->receiveDatagram().data();}}); // 如果udp2里有接收到数据报，就打印udp1->writeDatagram("hello,world", QHostAddress("224.1.1.1"), 6666); // 发送数据return a.exec();
}

广播

广播就是把多播发送地址改成255.255.255.255,并且客户端 不需要加入多播组，其他操作一样

#include <QCoreApplication>
#include <QNetworkDatagram>
#include <QUdpSocket>int main(int argc, char* argv[])
{QCoreApplication a(argc, argv);// 广播QUdpSocket* udp1 = new QUdpSocket;QUdpSocket* udp2 = new QUdpSocket;udp2->bind(QHostAddress::AnyIPv4, 6666, QUdpSocket::ShareAddress | QUdpSocket::ReuseAddressHint);QObject::connect(udp2, &QUdpSocket::readyRead, [=] {while (udp2->hasPendingDatagrams()) {qDebug() << udp2->receiveDatagram().data();}}); // 如果udp2里有接收到数据报，就打印udp1->writeDatagram("hello,world", QHostAddress("255.255.255.255"), 6666); // 发送数据return a.exec();
}

网络访问

QNetworkAccessManager

QNetworkRequest

QNetworkReply

实操

类似于python爬虫的request请求

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>int main(int argc, char* argv[])
{QCoreApplication a(argc, argv);QNetworkAccessManager* manager = new QNetworkAccessManager;QNetworkRequest request;request.setUrl(QUrl("https://baike.baidu.com/item/12/1016?fr=ge_ala"));manager->get(request);QObject::connect(manager, &QNetworkAccessManager::finished, [=](QNetworkReply* reply) {qDebug() << QString::fromUtf8(reply->readAll());});return a.exec();
}