問題描述

我正在嘗試在特定線程中啟動 QTimer.但是，計時器似乎沒有執行，也沒有打印出任何內容.是跟定時器、槽還是線程有關?

I am trying to start a QTimer in a specific thread. However, the timer does not seem to execute and nothing is printing out. Is it something to do with the timer, the slot or the thread?

main.cpp

    #include "MyThread.h"
    #include <iostream>
    using namespace std;

    int main(int argc, char *argv[]) {
        MyThread t;
        t.start();
        while(1);
    }

MyThread.h

    #ifndef MYTHREAD_H
    #define MYTHREAD_H

    #include <QTimer>
    #include <QThread>
    #include <iostream>

    class MyThread : public QThread {
        Q_OBJECT
    public:
        MyThread();
    public slots:
        void doIt();
    protected:
        void run();
    };

    #endif  /* MYTHREAD_H */

MyThread.cpp

MyThread.cpp

    #include "MyThread.h"

    using namespace std;

    MyThread::MyThread() {
        moveToThread(this);
    }

    void MyThread::run() {
        QTimer* timer = new QTimer(this);
        timer->setInterval(1);
        timer->connect(timer, SIGNAL(timeout()), this, SLOT(doIt()));
        timer->start();
    }

    void MyThread::doIt(){
        cout << "it works";
    }

推薦答案

正如我所評論的(鏈接中的更多信息)，您做錯了:

As I commented (further information in the link) you are doing it wrong :

1. 您將保存線程數據的對象與另一個對象(負責 doIt())混合在一起.他們應該分開.
2. 在您的情況下，無需對 QThread 進行子類化.更糟糕的是，您覆蓋了 run 方法，而沒有考慮它在做什么.

1. You are mixing the object holding thread data with another object (responsible of doIt()). They should be separated.
2. There is no need to subclass QThread in your case. Worse, you are overriding the run method without any consideration of what it was doing.

這部分代碼應該夠了

QThread* somethread = new QThread(this);
QTimer* timer = new QTimer(0); //parent must be null
timer->setInterval(1);
timer->moveToThread(somethread);
//connect what you want
somethread->start();

現在(Qt 版本 >= 4.7)默認 QThread 在他的 run() 方法中啟動一個事件循環.為了在線程內運行，您只需要移動對象.閱讀文檔...

Now (Qt version >= 4.7) by default QThread starts a event loop in his run() method. In order to run inside a thread, you just need to move the object. Read the doc...

這篇關于在 QThread 中啟動 QTimer的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！