WebSockets MQTT 订阅范例

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#include "clientsubscription.h"
#include <QtCore/QCoreApplication>
#include <QtCore/QCommandLineParser>
#include <QtCore/QLoggingCategory>
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QCoreApplication::setApplicationVersion("1.0");
    QCommandLineParser parser;
    parser.setApplicationDescription(QLatin1String("Websocket MQTT subscription tool"));
    auto help = parser.addHelpOption();
    // Use http://www.hivemq.com/demos/websocket-client/ in browser to publish
    QCommandLineOption urlOption(QStringList() << "host" << "url" << "broker",
                                 QStringLiteral("Host to connect to, eg ws://broker.hivemq.com:8000/mqtt"),
                                 "host");
    parser.addOption(urlOption);
    QCommandLineOption subscriptionOption(QStringList() << "t" << "topic",
                                          QStringLiteral("Topic to subscribe to"), "topic");
    parser.addOption(subscriptionOption);
    QCommandLineOption debugOption(QStringList() << "d" << "debug",
                                   QStringLiteral("Enable Debug mode"));
    parser.addOption(debugOption);
    QCommandLineOption versionOption(QStringList() << "v" << "version",
                                     QStringLiteral("MQTT protocol version.\n3: MQTT 3.1\n4: MQTT 3.1.1"),
                                     "version", "3");
    parser.addOption(versionOption);
    parser.process(a.arguments());
    const QString debugLog = QString::fromLatin1("qtdemo.websocket.mqtt*=%1").arg(
                                parser.isSet(debugOption) ? "true" : "false");
    QLoggingCategory::setFilterRules(debugLog);
    ClientSubscription clientsub;
    clientsub.setUrl(QUrl(parser.value(urlOption)));
    clientsub.setTopic(parser.value(subscriptionOption));
    const QString versionString = parser.value(versionOption);
    if (versionString == "4") {
        clientsub.setVersion(4);
    } else if (versionString == "3") {
        clientsub.setVersion(3);
    } else {
        qInfo() << "Unknown MQTT version";
        return -2;
    }
    clientsub.connectAndSubscribe();
    return a.exec();
}