使用 Qthread-Qt5 创建新线程 [英] creating new thread using Qthread-Qt5

问题描述

我正在尝试创建一个应该在后台运行的新线程 gpsthread，并存储该值.

I am trying to create a new thread gpsthread which should run in the back ground, and store the value.

class gpsthread: public QThread{
    Q_OBJECT
private:nrega_status_t status2;

public: 
explicit gpsthread(QObject *parent = 0):QThread(parent) {
    // QTimer *t = new QTimer(this);
    // connect(t, SIGNAL(timeout()), this, SLOT(processgps()));
    // t->start(10000);
 }
 void run(){
    qDebug()<<"inside gps thread\n";
    QTimer *t = new QTimer(this);
     connect(t, SIGNAL(timeout()), this, SLOT(processgps()));
     t->start(10000);
    }

public slots:void processgps(){
    int status2;
    status2=gps_management();
}
};

我的主要课程是快速浏览.

My main class is quickview.

int main(int argc, char *argv[])
{

QString file = "qml/main.qml";
QApplication app(argc, argv);
TranslationTest myObj;
QuickView view;
subthread object;
gpsthread obj;
gprsthread gprs;
view.rootContext()->setContextProperty("rootItem", (QObject *)&myObj);

    obj.start();
//from subthread
QObject::connect(&object, SIGNAL(batterytoqml(QVariant,QVariant)),item, SLOT(frombattery(QVariant,QVariant)));
QObject::connect(&gprs, SIGNAL(gprstoqml(QVariant)),item, SLOT(fromgprs(QVariant)));
return app.exec();

}

我也试过了

class gpsthread: public QThread{
    Q_OBJECT
private:nrega_status_t status2;

public:QTimer* t; 
explicit gpsthread(QObject *parent = 0):QThread(parent) {
    // QTimer *t = new QTimer(this);
    // connect(t, SIGNAL(timeout()), this, SLOT(processgps()));
    // t->start(10000);
 }
 void run(){
    qDebug()<<"inside gps thread\n";
    t = new QTimer(this);
     connect(t, SIGNAL(timeout()), this, SLOT(processgps()));
     t->start(10000);
exec();    
}

public slots:void processgps(){
    int status2;
    status2=gps_management();
}
};

但是提示错误

 QObject: Cannot create children for a parent that is in a different thread

如果我在构造函数中创建对象，那么它也会给出相同的错误，因为该对象将在主线程中创建.如何解决这个问题?

If I create object in constructor then also it will give the same error because the object will be created in the main thread. How to resolve this?

推荐答案

从 QThread 继承不是推荐的用法.QThread 是一个运行事件循环的完整类，这通常是您需要的.文档 建议使用从 QObject 继承的工作对象并在一个插槽.工作线程被移动到 QThread 中.当发送连接信号时，槽将运行在正确的线程中.

Inheriting from QThread is not the recommended usage. QThread is a complete class that runs an event loop, which is generally what you need. The documentation recommends using a worker object that inherits from QObject and does work in a slot. The worker is moved into a QThread. When a connected signal is sent, the slot will run in the correct thread.

class gpsworker: public QObject
{
Q_OBJECT
public:
    explicit gpsworker(QObject *parent = 0):
    QObject(parent)
    {}

public slots:
    void processgps() {
        qDebug() << "processgps()" << QThread::currentThreadId();
    }
}

void OwnerClass::startWorker() {
    QTimer *timer = new QTimer(this);
    QThread *thread = new QThread(this);
    this->worker = new gpsworker();
    this->worker->moveToThread(thread);
    connect(timer, SIGNAL(timeout()), this->worker, SLOT(processgps()) );
    connect(thread, SIGNAL(finished()), this->worker, SLOT(deleteLater()) );
    thread->start();
    timer->start();
}

如果你想让定时器也存在于另一个线程中，QTimer::start 是一个槽.

If you want the timer to live in the other thread as well, QTimer::start is a slot.

这篇关于使用 Qthread-Qt5 创建新线程的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！